From 37dd61b229225edc691763fd95085cd660b62633 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Mon, 17 Aug 2026 20:20:21 +0900
Subject: [PATCH 01/18] WS2812B

---
 firmware/firmware.ino | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index c82f9c3..c242f17 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -1,6 +1,12 @@
 #include "BluetoothA2DPSink.h"
 #include <Wire.h>
 #include <U8g2lib.h>
+#include <Adafruit_NeoPixel.h>
+
+// WS2812B設定
+constexpr uint8_t WS2812B_PIN = 13;
+constexpr uint16_t WS2812B_COUNT = 1;
+Adafruit_NeoPixel ws2812b(WS2812B_COUNT, WS2812B_PIN, NEO_GRB + NEO_KHZ800);
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
@@ -77,6 +83,12 @@ void volume_changed_callback(int volume) {
 void setup() {
   Serial.begin(115200);
 
+  // WS2812Bを緑で点灯
+  ws2812b.begin();
+  ws2812b.setBrightness(255);
+  ws2812b.setPixelColor(0, ws2812b.Color(0, 255, 0));
+  ws2812b.show();
+
   // SDAをGPIO 19、SCLをGPIO 32 に設定
   // （配線に合わせて Wire.begin(SDA_PIN, SCL_PIN) の順で指定します）
   Wire.begin(19, 5);

From 9f28dc5d6915d82df6634cc47045457484809fc6 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Mon, 17 Aug 2026 20:57:25 +0900
Subject: [PATCH 02/18] =?UTF-8?q?7=E8=89=B2=E5=A4=89=E5=8C=96?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/firmware.ino | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index c242f17..e1a465a 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -4,9 +4,18 @@
 #include <Adafruit_NeoPixel.h>
 
 // WS2812B設定
-constexpr uint8_t WS2812B_PIN = 13;
+constexpr uint8_t WS2812B_PIN = 16;
 constexpr uint16_t WS2812B_COUNT = 1;
 Adafruit_NeoPixel ws2812b(WS2812B_COUNT, WS2812B_PIN, NEO_GRB + NEO_KHZ800);
+const uint32_t ws2812bColors[] = {
+  0xFF0000, 0xFF8000, 0xFFFF00, 0x00FF00,
+  0x0000FF, 0x4B0082, 0x8F00FF
+};
+constexpr uint8_t WS2812B_COLOR_COUNT = sizeof(ws2812bColors) / sizeof(ws2812bColors[0]);
+constexpr unsigned long WS2812B_INTERVAL_MS = 500;
+bool isPlaying = false;
+uint8_t ws2812bColorIndex = 0;
+unsigned long lastWs2812bUpdate = 0;
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
@@ -80,13 +89,23 @@ void volume_changed_callback(int volume) {
   updateDisplay();
 }
 
+void audio_state_changed_callback(esp_a2d_audio_state_t state) {
+  isPlaying = (state == ESP_A2D_AUDIO_STATE_STARTED);
+
+  if (!isPlaying) {
+    ws2812bColorIndex = 3;
+    ws2812b.setPixelColor(0, ws2812bColors[ws2812bColorIndex]);
+    ws2812b.show();
+  }
+}
+
 void setup() {
   Serial.begin(115200);
 
   // WS2812Bを緑で点灯
   ws2812b.begin();
   ws2812b.setBrightness(255);
-  ws2812b.setPixelColor(0, ws2812b.Color(0, 255, 0));
+  ws2812b.setPixelColor(0, ws2812bColors[3]);
   ws2812b.show();
 
   // SDAをGPIO 19、SCLをGPIO 32 に設定
@@ -100,7 +119,7 @@ void setup() {
   // 初期画面
   u8g2.clearBuffer();
   u8g2.setFont(u8g2_font_unifont_t_japanese1);
-  u8g2.drawUTF8(0, 20, "BTスピーカー5.2");
+  u8g2.drawUTF8(0, 20, "BTスピーカー5.3");
   u8g2.setFont(u8g2_font_6x10_tf);
   u8g2.drawStr(0, 40, "Ready...");
   u8g2.sendBuffer();
@@ -118,10 +137,17 @@ void setup() {
   // コールバック登録
   a2dp_sink.set_avrc_metadata_callback(avrc_metadata_callback);
   a2dp_sink.set_on_volumechange(volume_changed_callback);
+  a2dp_sink.set_on_audio_state_changed(audio_state_changed_callback);
 
   // Bluetooth起動
-  a2dp_sink.start("BT_Speaker5.2");
+  a2dp_sink.start("BT_Speaker5.3");
 }
 
 void loop() {
+  if (isPlaying && millis() - lastWs2812bUpdate >= WS2812B_INTERVAL_MS) {
+    lastWs2812bUpdate = millis();
+    ws2812bColorIndex = (ws2812bColorIndex + 1) % WS2812B_COLOR_COUNT;
+    ws2812b.setPixelColor(0, ws2812bColors[ws2812bColorIndex]);
+    ws2812b.show();
+  }
 }
\ No newline at end of file

From b41e20f5a252f39d611e01766964af6ed3744609 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Mon, 17 Aug 2026 21:15:10 +0900
Subject: [PATCH 03/18] =?UTF-8?q?=E5=A4=89=E5=8C=96=E3=82=92=E3=82=86?=
 =?UTF-8?q?=E3=81=A3=E3=81=8F=E3=82=8A?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/firmware.ino | 34 +++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index e1a465a..f0cd2a1 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -12,10 +12,12 @@ const uint32_t ws2812bColors[] = {
   0x0000FF, 0x4B0082, 0x8F00FF
 };
 constexpr uint8_t WS2812B_COLOR_COUNT = sizeof(ws2812bColors) / sizeof(ws2812bColors[0]);
-constexpr unsigned long WS2812B_INTERVAL_MS = 500;
+constexpr unsigned long WS2812B_INTERVAL_MS = 30;
+constexpr unsigned long WS2812B_TRANSITION_MS = 3000;
 bool isPlaying = false;
 uint8_t ws2812bColorIndex = 0;
 unsigned long lastWs2812bUpdate = 0;
+unsigned long ws2812bTransitionStart = 0;
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
@@ -89,9 +91,14 @@ void volume_changed_callback(int volume) {
   updateDisplay();
 }
 
-void audio_state_changed_callback(esp_a2d_audio_state_t state) {
+void audio_state_changed_callback(esp_a2d_audio_state_t state, void *) {
   isPlaying = (state == ESP_A2D_AUDIO_STATE_STARTED);
 
+  if (isPlaying) {
+    ws2812bTransitionStart = millis();
+    lastWs2812bUpdate = ws2812bTransitionStart;
+  }
+
   if (!isPlaying) {
     ws2812bColorIndex = 3;
     ws2812b.setPixelColor(0, ws2812bColors[ws2812bColorIndex]);
@@ -145,9 +152,26 @@ void setup() {
 
 void loop() {
   if (isPlaying && millis() - lastWs2812bUpdate >= WS2812B_INTERVAL_MS) {
-    lastWs2812bUpdate = millis();
-    ws2812bColorIndex = (ws2812bColorIndex + 1) % WS2812B_COLOR_COUNT;
-    ws2812b.setPixelColor(0, ws2812bColors[ws2812bColorIndex]);
+    unsigned long now = millis();
+    lastWs2812bUpdate = now;
+    unsigned long transitionElapsed = now - ws2812bTransitionStart;
+    if (transitionElapsed >= WS2812B_TRANSITION_MS) {
+      ws2812bColorIndex = (ws2812bColorIndex + transitionElapsed / WS2812B_TRANSITION_MS)
+        % WS2812B_COLOR_COUNT;
+      ws2812bTransitionStart = now;
+      transitionElapsed = 0;
+    }
+    uint8_t nextColorIndex = (ws2812bColorIndex + 1) % WS2812B_COLOR_COUNT;
+    uint32_t currentColor = ws2812bColors[ws2812bColorIndex];
+    uint32_t nextColor = ws2812bColors[nextColorIndex];
+    uint8_t red = ((currentColor >> 16) * (WS2812B_TRANSITION_MS - transitionElapsed)
+      + (nextColor >> 16) * transitionElapsed) / WS2812B_TRANSITION_MS;
+    uint8_t green = (((currentColor >> 8) & 0xFF) * (WS2812B_TRANSITION_MS - transitionElapsed)
+      + ((nextColor >> 8) & 0xFF) * transitionElapsed) / WS2812B_TRANSITION_MS;
+    uint8_t blue = ((currentColor & 0xFF) * (WS2812B_TRANSITION_MS - transitionElapsed)
+      + (nextColor & 0xFF) * transitionElapsed) / WS2812B_TRANSITION_MS;
+    ws2812b.setPixelColor(0, red, green, blue);
     ws2812b.show();
+
   }
 }
\ No newline at end of file

From 38893368293e17e1abc24b8d6bc5a8c57f1c1a18 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Thu, 3 Sep 2026 09:39:58 +0900
Subject: [PATCH 04/18] =?UTF-8?q?PIN=E7=95=AA=E5=8F=B7=E5=A4=89=E6=9B=B4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/firmware.ino | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index f0cd2a1..ffbb598 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -4,7 +4,7 @@
 #include <Adafruit_NeoPixel.h>
 
 // WS2812B設定
-constexpr uint8_t WS2812B_PIN = 16;
+constexpr uint8_t WS2812B_PIN = 18;
 constexpr uint16_t WS2812B_COUNT = 1;
 Adafruit_NeoPixel ws2812b(WS2812B_COUNT, WS2812B_PIN, NEO_GRB + NEO_KHZ800);
 const uint32_t ws2812bColors[] = {
@@ -117,7 +117,7 @@ void setup() {
 
   // SDAをGPIO 19、SCLをGPIO 32 に設定
   // （配線に合わせて Wire.begin(SDA_PIN, SCL_PIN) の順で指定します）
-  Wire.begin(19, 5);
+  Wire.begin(21, 22);
   
   // OLED初期化
   u8g2.begin();

From 48cf4020c31189a781abdcd1d19b907373ed6000 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Thu, 3 Sep 2026 09:55:45 +0900
Subject: [PATCH 05/18] =?UTF-8?q?NeoPixcel=20=E3=83=A2=E3=82=B8=E3=83=A5?=
 =?UTF-8?q?=E3=83=BC=E3=83=AB=E5=8C=96?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/NeoPixelController.cpp | 63 +++++++++++++++++++++++++++++++++
 firmware/NeoPixelController.h   | 20 +++++++++++
 firmware/firmware.ino           | 62 +++-----------------------------
 3 files changed, 88 insertions(+), 57 deletions(-)
 create mode 100644 firmware/NeoPixelController.cpp
 create mode 100644 firmware/NeoPixelController.h

diff --git a/firmware/NeoPixelController.cpp b/firmware/NeoPixelController.cpp
new file mode 100644
index 0000000..b67c73a
--- /dev/null
+++ b/firmware/NeoPixelController.cpp
@@ -0,0 +1,63 @@
+#include "NeoPixelController.h"
+
+#include <Adafruit_NeoPixel.h>
+
+namespace {
+constexpr uint8_t kPin = 18;
+constexpr uint16_t kCount = 1;
+constexpr uint32_t kColors[] = {
+  0xFF0000, 0xFF8000, 0xFFFF00, 0x00FF00,
+  0x0000FF, 0x4B0082, 0x8F00FF
+};
+constexpr uint8_t kColorCount = sizeof(kColors) / sizeof(kColors[0]);
+
+Adafruit_NeoPixel pixels(kCount, kPin, NEO_GRB + NEO_KHZ800);
+}
+
+void NeoPixelController::begin() {
+  pixels.begin();
+  pixels.setBrightness(255);
+  pixels.setPixelColor(0, kColors[kStoppedColorIndex]);
+  pixels.show();
+}
+
+void NeoPixelController::setPlaying(bool playing) {
+  isPlaying_ = playing;
+
+  if (isPlaying_) {
+    transitionStart_ = millis();
+    lastUpdate_ = transitionStart_;
+    return;
+  }
+
+  colorIndex_ = kStoppedColorIndex;
+  pixels.setPixelColor(0, kColors[colorIndex_]);
+  pixels.show();
+}
+
+void NeoPixelController::update() {
+  if (!isPlaying_ || millis() - lastUpdate_ < kUpdateIntervalMs) {
+    return;
+  }
+
+  unsigned long now = millis();
+  lastUpdate_ = now;
+  unsigned long transitionElapsed = now - transitionStart_;
+  if (transitionElapsed >= kTransitionMs) {
+    colorIndex_ = (colorIndex_ + transitionElapsed / kTransitionMs) % kColorCount;
+    transitionStart_ = now;
+    transitionElapsed = 0;
+  }
+
+  uint8_t nextColorIndex = (colorIndex_ + 1) % kColorCount;
+  uint32_t currentColor = kColors[colorIndex_];
+  uint32_t nextColor = kColors[nextColorIndex];
+  uint8_t red = ((currentColor >> 16) * (kTransitionMs - transitionElapsed)
+    + (nextColor >> 16) * transitionElapsed) / kTransitionMs;
+  uint8_t green = (((currentColor >> 8) & 0xFF) * (kTransitionMs - transitionElapsed)
+    + ((nextColor >> 8) & 0xFF) * transitionElapsed) / kTransitionMs;
+  uint8_t blue = ((currentColor & 0xFF) * (kTransitionMs - transitionElapsed)
+    + (nextColor & 0xFF) * transitionElapsed) / kTransitionMs;
+  pixels.setPixelColor(0, red, green, blue);
+  pixels.show();
+}
\ No newline at end of file
diff --git a/firmware/NeoPixelController.h b/firmware/NeoPixelController.h
new file mode 100644
index 0000000..d9004f4
--- /dev/null
+++ b/firmware/NeoPixelController.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <Arduino.h>
+
+class NeoPixelController {
+public:
+  void begin();
+  void setPlaying(bool playing);
+  void update();
+
+private:
+  static constexpr uint8_t kStoppedColorIndex = 3;
+  static constexpr unsigned long kUpdateIntervalMs = 30;
+  static constexpr unsigned long kTransitionMs = 3000;
+
+  bool isPlaying_ = false;
+  uint8_t colorIndex_ = 0;
+  unsigned long lastUpdate_ = 0;
+  unsigned long transitionStart_ = 0;
+};
\ No newline at end of file
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index ffbb598..d7f224f 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -1,28 +1,13 @@
 #include "BluetoothA2DPSink.h"
 #include <Wire.h>
 #include <U8g2lib.h>
-#include <Adafruit_NeoPixel.h>
-
-// WS2812B設定
-constexpr uint8_t WS2812B_PIN = 18;
-constexpr uint16_t WS2812B_COUNT = 1;
-Adafruit_NeoPixel ws2812b(WS2812B_COUNT, WS2812B_PIN, NEO_GRB + NEO_KHZ800);
-const uint32_t ws2812bColors[] = {
-  0xFF0000, 0xFF8000, 0xFFFF00, 0x00FF00,
-  0x0000FF, 0x4B0082, 0x8F00FF
-};
-constexpr uint8_t WS2812B_COLOR_COUNT = sizeof(ws2812bColors) / sizeof(ws2812bColors[0]);
-constexpr unsigned long WS2812B_INTERVAL_MS = 30;
-constexpr unsigned long WS2812B_TRANSITION_MS = 3000;
-bool isPlaying = false;
-uint8_t ws2812bColorIndex = 0;
-unsigned long lastWs2812bUpdate = 0;
-unsigned long ws2812bTransitionStart = 0;
+#include "NeoPixelController.h"
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
 
 BluetoothA2DPSink a2dp_sink;
+NeoPixelController neoPixelController;
 
 // 表示用変数
 String currentTitle = "未接続";
@@ -92,28 +77,13 @@ void volume_changed_callback(int volume) {
 }
 
 void audio_state_changed_callback(esp_a2d_audio_state_t state, void *) {
-  isPlaying = (state == ESP_A2D_AUDIO_STATE_STARTED);
-
-  if (isPlaying) {
-    ws2812bTransitionStart = millis();
-    lastWs2812bUpdate = ws2812bTransitionStart;
-  }
-
-  if (!isPlaying) {
-    ws2812bColorIndex = 3;
-    ws2812b.setPixelColor(0, ws2812bColors[ws2812bColorIndex]);
-    ws2812b.show();
-  }
+  neoPixelController.setPlaying(state == ESP_A2D_AUDIO_STATE_STARTED);
 }
 
 void setup() {
   Serial.begin(115200);
 
-  // WS2812Bを緑で点灯
-  ws2812b.begin();
-  ws2812b.setBrightness(255);
-  ws2812b.setPixelColor(0, ws2812bColors[3]);
-  ws2812b.show();
+  neoPixelController.begin();
 
   // SDAをGPIO 19、SCLをGPIO 32 に設定
   // （配線に合わせて Wire.begin(SDA_PIN, SCL_PIN) の順で指定します）
@@ -151,27 +121,5 @@ void setup() {
 }
 
 void loop() {
-  if (isPlaying && millis() - lastWs2812bUpdate >= WS2812B_INTERVAL_MS) {
-    unsigned long now = millis();
-    lastWs2812bUpdate = now;
-    unsigned long transitionElapsed = now - ws2812bTransitionStart;
-    if (transitionElapsed >= WS2812B_TRANSITION_MS) {
-      ws2812bColorIndex = (ws2812bColorIndex + transitionElapsed / WS2812B_TRANSITION_MS)
-        % WS2812B_COLOR_COUNT;
-      ws2812bTransitionStart = now;
-      transitionElapsed = 0;
-    }
-    uint8_t nextColorIndex = (ws2812bColorIndex + 1) % WS2812B_COLOR_COUNT;
-    uint32_t currentColor = ws2812bColors[ws2812bColorIndex];
-    uint32_t nextColor = ws2812bColors[nextColorIndex];
-    uint8_t red = ((currentColor >> 16) * (WS2812B_TRANSITION_MS - transitionElapsed)
-      + (nextColor >> 16) * transitionElapsed) / WS2812B_TRANSITION_MS;
-    uint8_t green = (((currentColor >> 8) & 0xFF) * (WS2812B_TRANSITION_MS - transitionElapsed)
-      + ((nextColor >> 8) & 0xFF) * transitionElapsed) / WS2812B_TRANSITION_MS;
-    uint8_t blue = ((currentColor & 0xFF) * (WS2812B_TRANSITION_MS - transitionElapsed)
-      + (nextColor & 0xFF) * transitionElapsed) / WS2812B_TRANSITION_MS;
-    ws2812b.setPixelColor(0, red, green, blue);
-    ws2812b.show();
-
-  }
+  neoPixelController.update();
 }
\ No newline at end of file

From 37e6a14cf7fdcb9699eff86edd279e268b49e169 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 14:59:31 +0900
Subject: [PATCH 06/18] =?UTF-8?q?PIN=E7=95=AA=E5=8F=B7=E3=81=A8=E5=90=8D?=
 =?UTF-8?q?=E5=89=8D=E6=8C=87=E5=AE=9A=E4=BD=8D=E7=BD=AE=E5=A4=89=E6=9B=B4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/NeoPixelController.cpp | 6 +++---
 firmware/NeoPixelController.h   | 2 +-
 firmware/firmware.ino           | 8 +++++---
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/firmware/NeoPixelController.cpp b/firmware/NeoPixelController.cpp
index b67c73a..5624ebb 100644
--- a/firmware/NeoPixelController.cpp
+++ b/firmware/NeoPixelController.cpp
@@ -3,7 +3,6 @@
 #include <Adafruit_NeoPixel.h>
 
 namespace {
-constexpr uint8_t kPin = 18;
 constexpr uint16_t kCount = 1;
 constexpr uint32_t kColors[] = {
   0xFF0000, 0xFF8000, 0xFFFF00, 0x00FF00,
@@ -11,10 +10,11 @@ constexpr uint32_t kColors[] = {
 };
 constexpr uint8_t kColorCount = sizeof(kColors) / sizeof(kColors[0]);
 
-Adafruit_NeoPixel pixels(kCount, kPin, NEO_GRB + NEO_KHZ800);
+Adafruit_NeoPixel pixels(kCount, 0, NEO_GRB + NEO_KHZ800);
 }
 
-void NeoPixelController::begin() {
+void NeoPixelController::begin(uint8_t pin) {
+  pixels.setPin(pin);
   pixels.begin();
   pixels.setBrightness(255);
   pixels.setPixelColor(0, kColors[kStoppedColorIndex]);
diff --git a/firmware/NeoPixelController.h b/firmware/NeoPixelController.h
index d9004f4..f091f81 100644
--- a/firmware/NeoPixelController.h
+++ b/firmware/NeoPixelController.h
@@ -4,7 +4,7 @@
 
 class NeoPixelController {
 public:
-  void begin();
+  void begin(uint8_t pin);
   void setPlaying(bool playing);
   void update();
 
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index d7f224f..b311f48 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -3,6 +3,8 @@
 #include <U8g2lib.h>
 #include "NeoPixelController.h"
 
+const char kBluetoothName[] = "BT_Speaker5.31";
+
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
 
@@ -83,7 +85,7 @@ void audio_state_changed_callback(esp_a2d_audio_state_t state, void *) {
 void setup() {
   Serial.begin(115200);
 
-  neoPixelController.begin();
+  neoPixelController.begin(18);
 
   // SDAをGPIO 19、SCLをGPIO 32 に設定
   // （配線に合わせて Wire.begin(SDA_PIN, SCL_PIN) の順で指定します）
@@ -96,7 +98,7 @@ void setup() {
   // 初期画面
   u8g2.clearBuffer();
   u8g2.setFont(u8g2_font_unifont_t_japanese1);
-  u8g2.drawUTF8(0, 20, "BTスピーカー5.3");
+  u8g2.drawUTF8(0, 20, kBluetoothName);
   u8g2.setFont(u8g2_font_6x10_tf);
   u8g2.drawStr(0, 40, "Ready...");
   u8g2.sendBuffer();
@@ -117,7 +119,7 @@ void setup() {
   a2dp_sink.set_on_audio_state_changed(audio_state_changed_callback);
 
   // Bluetooth起動
-  a2dp_sink.start("BT_Speaker5.3");
+  a2dp_sink.start(kBluetoothName);
 }
 
 void loop() {

From 05afe2f4391a7a80bd1f9894092b93b3264b47d6 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 15:34:42 +0900
Subject: [PATCH 07/18] =?UTF-8?q?=E3=82=BB=E3=83=B3=E3=82=B5=E3=83=BC?=
 =?UTF-8?q?=E5=80=A4=E8=A1=A8=E7=A4=BA?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/firmware.ino | 89 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 79 insertions(+), 10 deletions(-)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index b311f48..067fc2c 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -1,24 +1,62 @@
 #include "BluetoothA2DPSink.h"
 #include <Wire.h>
 #include <U8g2lib.h>
+#include <Adafruit_AHTX0.h>
+#include <BH1750.h>
 #include "NeoPixelController.h"
 
-const char kBluetoothName[] = "BT_Speaker5.31";
+const char kBluetoothName[] = "BT_Speaker5.32";
+constexpr uint8_t kSoilMoisturePin = 32;
+constexpr unsigned long kSensorUpdateIntervalMs = 1000;
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
 
 BluetoothA2DPSink a2dp_sink;
 NeoPixelController neoPixelController;
+Adafruit_AHTX0 aht20;
+BH1750 bh1750;
 
 // 表示用変数
 String currentTitle = "未接続";
 String currentArtist = "";
 int currentVolumePercent = 0; // 音量 (0 ~ 100%)
+bool bluetoothConnected = false;
+bool aht20Ready = false;
+bool bh1750Ready = false;
+unsigned long lastSensorUpdate = 0;
+float temperature = 0.0f;
+float humidity = 0.0f;
+float illuminance = 0.0f;
+int soilMoisture = 0;
 
 // 画面全体を再描画する関数
 void updateDisplay() {
   u8g2.clearBuffer();
+
+  if (!bluetoothConnected) {
+    u8g2.setFont(u8g2_font_6x10_tf);
+
+    char sensorLine[32];
+    if (aht20Ready) {
+      snprintf(sensorLine, sizeof(sensorLine), "T:%5.1fC H:%5.1f%%", temperature, humidity);
+    } else {
+      snprintf(sensorLine, sizeof(sensorLine), "AHT20: error");
+    }
+    u8g2.drawStr(0, 12, sensorLine);
+
+    if (bh1750Ready) {
+      snprintf(sensorLine, sizeof(sensorLine), "Light: %6.1f lx", illuminance);
+    } else {
+      snprintf(sensorLine, sizeof(sensorLine), "BH1750: error");
+    }
+    u8g2.drawStr(0, 30, sensorLine);
+
+    snprintf(sensorLine, sizeof(sensorLine), "Soil: %4d", soilMoisture);
+    u8g2.drawStr(0, 48, sensorLine);
+    u8g2.sendBuffer();
+    return;
+  }
   
   // --------------------------------------------------
   // 1. 音量表示エリア（最上部：英数フォント）
@@ -67,7 +105,7 @@ void avrc_metadata_callback(uint8_t id, const uint8_t *text) {
     updated = true;
   }
 
-  if (updated) {
+  if (updated && bluetoothConnected) {
     updateDisplay();
   }
 }
@@ -75,13 +113,38 @@ void avrc_metadata_callback(uint8_t id, const uint8_t *text) {
 // 音量変更時のコールバック関数
 void volume_changed_callback(int volume) {
   currentVolumePercent = map(volume, 0, 127, 0, 100);
-  updateDisplay();
+  if (bluetoothConnected) {
+    updateDisplay();
+  }
 }
 
 void audio_state_changed_callback(esp_a2d_audio_state_t state, void *) {
   neoPixelController.setPlaying(state == ESP_A2D_AUDIO_STATE_STARTED);
 }
 
+void connection_state_changed_callback(esp_a2d_connection_state_t state, void *) {
+  bluetoothConnected = state == ESP_A2D_CONNECTION_STATE_CONNECTED;
+  updateDisplay();
+}
+
+void updateSensorDisplay() {
+  sensors_event_t humidityEvent;
+  sensors_event_t temperatureEvent;
+
+  if (aht20Ready) {
+    aht20.getEvent(&humidityEvent, &temperatureEvent);
+    temperature = temperatureEvent.temperature;
+    humidity = humidityEvent.relative_humidity;
+  }
+
+  if (bh1750Ready) {
+    illuminance = bh1750.readLightLevel();
+  }
+
+  soilMoisture = analogRead(kSoilMoisturePin);
+  updateDisplay();
+}
+
 void setup() {
   Serial.begin(115200);
 
@@ -95,13 +158,12 @@ void setup() {
   u8g2.begin();
   u8g2.enableUTF8Print(); // UTF-8（日本語）描画を有効化
 
-  // 初期画面
-  u8g2.clearBuffer();
-  u8g2.setFont(u8g2_font_unifont_t_japanese1);
-  u8g2.drawUTF8(0, 20, kBluetoothName);
-  u8g2.setFont(u8g2_font_6x10_tf);
-  u8g2.drawStr(0, 40, "Ready...");
-  u8g2.sendBuffer();
+  aht20Ready = aht20.begin();
+  bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
+  analogReadResolution(12);
+
+  updateSensorDisplay();
+  lastSensorUpdate = millis();
 
   // I2S ピン設定 (BCK: 27, WS: 25, DOUT: 26)
   i2s_pin_config_t my_pin_config = {
@@ -117,6 +179,7 @@ void setup() {
   a2dp_sink.set_avrc_metadata_callback(avrc_metadata_callback);
   a2dp_sink.set_on_volumechange(volume_changed_callback);
   a2dp_sink.set_on_audio_state_changed(audio_state_changed_callback);
+  a2dp_sink.set_on_connection_state_changed(connection_state_changed_callback);
 
   // Bluetooth起動
   a2dp_sink.start(kBluetoothName);
@@ -124,4 +187,10 @@ void setup() {
 
 void loop() {
   neoPixelController.update();
+
+  unsigned long now = millis();
+  if (!bluetoothConnected && now - lastSensorUpdate >= kSensorUpdateIntervalMs) {
+    lastSensorUpdate = now;
+    updateSensorDisplay();
+  }
 }
\ No newline at end of file

From 3279c296a0977f0cb9b986a944604db45ad5e3d4 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 16:13:03 +0900
Subject: [PATCH 08/18] =?UTF-8?q?BT=E3=82=B5=E3=83=9D=E3=83=BC=E3=83=88?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .github/workflows/build.yml |   5 ++
 firmware/SensorLogger.cpp   | 149 ++++++++++++++++++++++++++++++++++++
 firmware/SensorLogger.h     |  44 +++++++++++
 firmware/firmware.ino       |  64 +++-------------
 4 files changed, 209 insertions(+), 53 deletions(-)
 create mode 100644 firmware/SensorLogger.cpp
 create mode 100644 firmware/SensorLogger.h

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e4cf9ec..f3a5159 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -41,6 +41,11 @@ jobs:
       - name: Install U8g2 library
         run: arduino-cli lib install "U8g2"
 
+      - name: Install sensor libraries
+        run: |
+          arduino-cli lib install "Adafruit AHTX0"
+          arduino-cli lib install "BH1750"
+
       # コンパイル実行 (output-dir を指定して構成ファイルを確実に生成)
       - name: Compile Sketch
         run: |
diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
new file mode 100644
index 0000000..765094c
--- /dev/null
+++ b/firmware/SensorLogger.cpp
@@ -0,0 +1,149 @@
+#include "SensorLogger.h"
+
+#include <Adafruit_AHTX0.h>
+#include <BH1750.h>
+#include <time.h>
+
+namespace {
+Adafruit_AHTX0 aht20;
+BH1750 bh1750;
+bool aht20Ready = false;
+bool bh1750Ready = false;
+}
+
+void SensorLogger::begin(uint8_t soilPin, const char* bluetoothName) {
+  soilPin_ = soilPin;
+  bluetoothName_ = bluetoothName;
+  pinMode(soilPin_, INPUT);
+  analogReadResolution(12);
+
+  aht20Ready = aht20.begin();
+  bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
+
+  bluetooth_.begin(bluetoothName);
+  readAndStore();
+  lastMeasure_ = millis();
+}
+
+bool SensorLogger::update() {
+  processBluetooth();
+
+  unsigned long now = millis();
+  if (now - lastMeasure_ >= kMeasureIntervalMs) {
+    lastMeasure_ = now;
+    readAndStore();
+    return true;
+  }
+  return false;
+}
+
+const SensorReading& SensorLogger::latest() const {
+  return latest_;
+}
+
+bool SensorLogger::hasReading() const {
+  return logCount_ != 0;
+}
+
+void SensorLogger::readAndStore() {
+  sensors_event_t humidityEvent;
+  sensors_event_t temperatureEvent;
+  SensorReading reading = {};
+
+  if (aht20Ready) {
+    aht20.getEvent(&humidityEvent, &temperatureEvent);
+    reading.temperature = temperatureEvent.temperature;
+    reading.humidity = humidityEvent.relative_humidity;
+  }
+  if (bh1750Ready) {
+    reading.illuminance = bh1750.readLightLevel();
+  }
+  reading.soilMoisture = analogRead(soilPin_);
+  reading.timestamp = currentTimestamp();
+  latest_ = reading;
+
+  size_t writeIndex = (logStart_ + logCount_) % kMaxLogEntries;
+  if (logCount_ == kMaxLogEntries) {
+    log_[logStart_] = reading;
+    logStart_ = (logStart_ + 1) % kMaxLogEntries;
+  } else {
+    log_[writeIndex] = reading;
+    ++logCount_;
+  }
+}
+
+void SensorLogger::processBluetooth() {
+  while (bluetooth_.available()) {
+    char character = static_cast<char>(bluetooth_.read());
+    if (character == '\n' || character == '\r') {
+      if (commandBuffer_.length() != 0) {
+        processCommand(commandBuffer_);
+        commandBuffer_ = "";
+      }
+    } else if (commandBuffer_.length() < 64) {
+      commandBuffer_ += character;
+    }
+  }
+}
+
+void SensorLogger::processCommand(const String& command) {
+  if (command == "GET_LOG") {
+    sendLog();
+  } else if (command == "CLEAR_LOG") {
+    clearLog();
+    bluetooth_.println("OK_CLEARED");
+  } else if (command.startsWith("TIME:")) {
+    unsigned long epoch = command.substring(5).toInt();
+    unsigned int year;
+    unsigned int month;
+    unsigned int day;
+    unsigned int hour;
+    unsigned int minute;
+    unsigned int second;
+    if (sscanf(command.c_str(), "TIME:[%u,%u,%u,%u,%u,%u]",
+        &year, &month, &day, &hour, &minute, &second) == 6) {
+      struct tm date = {};
+      date.tm_year = year - 1900;
+      date.tm_mon = month - 1;
+      date.tm_mday = day;
+      date.tm_hour = hour;
+      date.tm_min = minute;
+      date.tm_sec = second;
+      epoch = static_cast<unsigned long>(mktime(&date));
+    }
+    if (epoch != 0) {
+      epochOffset_ = epoch - millis() / 1000UL;
+      timeSynchronized_ = true;
+      bluetooth_.println("OK_TIME");
+    } else {
+      bluetooth_.println("ERROR_TIME");
+    }
+  }
+}
+
+void SensorLogger::sendLog() {
+  bluetooth_.println("timestamp,temp,humid,light,soil,device");
+  for (size_t index = 0; index < logCount_; ++index) {
+    size_t logIndex = (logStart_ + index) % kMaxLogEntries;
+    const SensorReading& reading = log_[logIndex];
+    bluetooth_.printf("%lu,%.2f,%.2f,%.2f,%u,%s\n",
+      reading.timestamp,
+      reading.temperature,
+      reading.humidity,
+      reading.illuminance,
+      reading.soilMoisture,
+      bluetoothName_);
+    delay(20);
+  }
+  bluetooth_.println("END_LOG");
+}
+
+void SensorLogger::clearLog() {
+  logStart_ = 0;
+  logCount_ = 0;
+}
+
+unsigned long SensorLogger::currentTimestamp() const {
+  unsigned long elapsedSeconds = millis() / 1000UL;
+  return timeSynchronized_ ? epochOffset_ + elapsedSeconds : elapsedSeconds;
+}
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
new file mode 100644
index 0000000..482cd3a
--- /dev/null
+++ b/firmware/SensorLogger.h
@@ -0,0 +1,44 @@
+#pragma once
+
+#include <Arduino.h>
+#include <BluetoothSerial.h>
+
+struct SensorReading {
+  unsigned long timestamp;
+  float temperature;
+  float humidity;
+  float illuminance;
+  uint16_t soilMoisture;
+};
+
+class SensorLogger {
+public:
+  static constexpr size_t kMaxLogEntries = 2000;
+
+  void begin(uint8_t soilPin, const char* bluetoothName);
+  bool update();
+  const SensorReading& latest() const;
+  bool hasReading() const;
+
+private:
+  static constexpr unsigned long kMeasureIntervalMs = 3600000UL;
+
+  void readAndStore();
+  void processBluetooth();
+  void processCommand(const String& command);
+  void sendLog();
+  void clearLog();
+  unsigned long currentTimestamp() const;
+
+  BluetoothSerial bluetooth_;
+  SensorReading log_[kMaxLogEntries] = {};
+  SensorReading latest_ = {};
+  size_t logStart_ = 0;
+  size_t logCount_ = 0;
+  uint8_t soilPin_ = 0;
+  unsigned long lastMeasure_ = 0;
+  unsigned long epochOffset_ = 0;
+  bool timeSynchronized_ = false;
+  const char* bluetoothName_ = "";
+  String commandBuffer_;
+};
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 067fc2c..5dab087 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -1,34 +1,23 @@
 #include "BluetoothA2DPSink.h"
 #include <Wire.h>
 #include <U8g2lib.h>
-#include <Adafruit_AHTX0.h>
-#include <BH1750.h>
 #include "NeoPixelController.h"
+#include "SensorLogger.h"
 
 const char kBluetoothName[] = "BT_Speaker5.32";
-constexpr uint8_t kSoilMoisturePin = 32;
-constexpr unsigned long kSensorUpdateIntervalMs = 1000;
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
 
 BluetoothA2DPSink a2dp_sink;
 NeoPixelController neoPixelController;
-Adafruit_AHTX0 aht20;
-BH1750 bh1750;
+SensorLogger sensorLogger;
 
 // 表示用変数
 String currentTitle = "未接続";
 String currentArtist = "";
 int currentVolumePercent = 0; // 音量 (0 ~ 100%)
 bool bluetoothConnected = false;
-bool aht20Ready = false;
-bool bh1750Ready = false;
-unsigned long lastSensorUpdate = 0;
-float temperature = 0.0f;
-float humidity = 0.0f;
-float illuminance = 0.0f;
-int soilMoisture = 0;
 
 // 画面全体を再描画する関数
 void updateDisplay() {
@@ -36,23 +25,17 @@ void updateDisplay() {
 
   if (!bluetoothConnected) {
     u8g2.setFont(u8g2_font_6x10_tf);
+    const SensorReading& reading = sensorLogger.latest();
 
     char sensorLine[32];
-    if (aht20Ready) {
-      snprintf(sensorLine, sizeof(sensorLine), "T:%5.1fC H:%5.1f%%", temperature, humidity);
-    } else {
-      snprintf(sensorLine, sizeof(sensorLine), "AHT20: error");
-    }
+    snprintf(sensorLine, sizeof(sensorLine), "T:%5.1fC H:%5.1f%%",
+      reading.temperature, reading.humidity);
     u8g2.drawStr(0, 12, sensorLine);
 
-    if (bh1750Ready) {
-      snprintf(sensorLine, sizeof(sensorLine), "Light: %6.1f lx", illuminance);
-    } else {
-      snprintf(sensorLine, sizeof(sensorLine), "BH1750: error");
-    }
+    snprintf(sensorLine, sizeof(sensorLine), "Light: %6.1f lx", reading.illuminance);
     u8g2.drawStr(0, 30, sensorLine);
 
-    snprintf(sensorLine, sizeof(sensorLine), "Soil: %4d", soilMoisture);
+    snprintf(sensorLine, sizeof(sensorLine), "Soil: %4u", reading.soilMoisture);
     u8g2.drawStr(0, 48, sensorLine);
     u8g2.sendBuffer();
     return;
@@ -127,24 +110,6 @@ void connection_state_changed_callback(esp_a2d_connection_state_t state, void *)
   updateDisplay();
 }
 
-void updateSensorDisplay() {
-  sensors_event_t humidityEvent;
-  sensors_event_t temperatureEvent;
-
-  if (aht20Ready) {
-    aht20.getEvent(&humidityEvent, &temperatureEvent);
-    temperature = temperatureEvent.temperature;
-    humidity = humidityEvent.relative_humidity;
-  }
-
-  if (bh1750Ready) {
-    illuminance = bh1750.readLightLevel();
-  }
-
-  soilMoisture = analogRead(kSoilMoisturePin);
-  updateDisplay();
-}
-
 void setup() {
   Serial.begin(115200);
 
@@ -158,12 +123,8 @@ void setup() {
   u8g2.begin();
   u8g2.enableUTF8Print(); // UTF-8（日本語）描画を有効化
 
-  aht20Ready = aht20.begin();
-  bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
-  analogReadResolution(12);
-
-  updateSensorDisplay();
-  lastSensorUpdate = millis();
+  sensorLogger.begin(32, kBluetoothName);
+  updateDisplay();
 
   // I2S ピン設定 (BCK: 27, WS: 25, DOUT: 26)
   i2s_pin_config_t my_pin_config = {
@@ -187,10 +148,7 @@ void setup() {
 
 void loop() {
   neoPixelController.update();
-
-  unsigned long now = millis();
-  if (!bluetoothConnected && now - lastSensorUpdate >= kSensorUpdateIntervalMs) {
-    lastSensorUpdate = now;
-    updateSensorDisplay();
+  if (sensorLogger.update() && !bluetoothConnected) {
+    updateDisplay();
   }
 }
\ No newline at end of file

From 68a5f0dcce21670943b6b91297fe87ec53dd2112 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 16:34:30 +0900
Subject: [PATCH 09/18] =?UTF-8?q?EnvLog=E3=82=B5=E3=83=9D=E3=83=BC?=
 =?UTF-8?q?=E3=83=88?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/SensorLogger.cpp | 113 ++++++++++++++++++++++++++++++++------
 firmware/SensorLogger.h   |  15 +++--
 firmware/firmware.ino     |   2 +-
 3 files changed, 109 insertions(+), 21 deletions(-)

diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index 765094c..8bd63bd 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -2,25 +2,76 @@
 
 #include <Adafruit_AHTX0.h>
 #include <BH1750.h>
+#include <BLE2902.h>
+#include <BLEDevice.h>
+#include <BLEServer.h>
+#include <BLEUtils.h>
 #include <time.h>
 
 namespace {
+constexpr char kNusServiceUuid[] = "6E400001-B5A3-F393-E0A9-E50E24DCCA9E";
+constexpr char kNusRxUuid[] = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E";
+constexpr char kNusTxUuid[] = "6E400003-B5A3-F393-E0A9-E50E24DCCA9E";
+
 Adafruit_AHTX0 aht20;
 BH1750 bh1750;
 bool aht20Ready = false;
 bool bh1750Ready = false;
 }
 
-void SensorLogger::begin(uint8_t soilPin, const char* bluetoothName) {
+class SensorLoggerCallbacks : public BLECharacteristicCallbacks {
+public:
+  explicit SensorLoggerCallbacks(SensorLogger* logger) : logger_(logger) {}
+
+  void onWrite(BLECharacteristic* characteristic) override {
+    logger_->receiveBluetoothData(characteristic->getValue().c_str());
+  }
+
+private:
+  SensorLogger* logger_;
+};
+
+class SensorLoggerServerCallbacks : public BLEServerCallbacks {
+public:
+  void onConnect(BLEServer*) override {}
+
+  void onDisconnect(BLEServer* server) override {
+    server->startAdvertising();
+  }
+};
+
+void SensorLogger::begin(uint8_t soilPin) {
   soilPin_ = soilPin;
-  bluetoothName_ = bluetoothName;
   pinMode(soilPin_, INPUT);
   analogReadResolution(12);
 
   aht20Ready = aht20.begin();
   bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
 
-  bluetooth_.begin(bluetoothName);
+  uint64_t mac = ESP.getEfuseMac();
+  char name[14];
+  snprintf(name, sizeof(name), "EnvLog-%05llX", mac & 0xFFFFF);
+  bluetoothName_ = name;
+  BLEDevice::init(bluetoothName_.c_str());
+
+  server_ = BLEDevice::createServer();
+  server_->setCallbacks(new SensorLoggerServerCallbacks());
+  BLEService* service = server_->createService(kNusServiceUuid);
+  BLECharacteristic* rxCharacteristic = service->createCharacteristic(
+    kNusRxUuid, BLECharacteristic::PROPERTY_WRITE | BLECharacteristic::PROPERTY_WRITE_NR);
+  rxCharacteristic->setCallbacks(new SensorLoggerCallbacks(this));
+  txCharacteristic_ = service->createCharacteristic(
+    kNusTxUuid, BLECharacteristic::PROPERTY_NOTIFY);
+  txCharacteristic_->addDescriptor(new BLE2902());
+  service->start();
+
+  BLEAdvertising* advertising = BLEDevice::getAdvertising();
+  advertising->addServiceUUID(kNusServiceUuid);
+  advertising->setScanResponse(true);
+  advertising->setMinPreferred(0x06);
+  advertising->setMinPreferred(0x12);
+  BLEDevice::startAdvertising();
+
   readAndStore();
   lastMeasure_ = millis();
 }
@@ -73,13 +124,25 @@ void SensorLogger::readAndStore() {
 }
 
 void SensorLogger::processBluetooth() {
-  while (bluetooth_.available()) {
-    char character = static_cast<char>(bluetooth_.read());
+  while (commandBuffer_.indexOf('\n') >= 0 || commandBuffer_.indexOf('\r') >= 0) {
+    int lineEnd = commandBuffer_.indexOf('\n');
+    int carriageReturn = commandBuffer_.indexOf('\r');
+    if (lineEnd < 0 || (carriageReturn >= 0 && carriageReturn < lineEnd)) {
+      lineEnd = carriageReturn;
+    }
+    String command = commandBuffer_.substring(0, lineEnd);
+    commandBuffer_.remove(0, lineEnd + 1);
+    if (command.length() != 0) {
+      processCommand(command);
+    }
+  }
+}
+
+void SensorLogger::receiveBluetoothData(const String& data) {
+  for (size_t index = 0; index < data.length(); ++index) {
+    char character = data[index];
     if (character == '\n' || character == '\r') {
-      if (commandBuffer_.length() != 0) {
-        processCommand(commandBuffer_);
-        commandBuffer_ = "";
-      }
+      commandBuffer_ += character;
     } else if (commandBuffer_.length() < 64) {
       commandBuffer_ += character;
     }
@@ -91,7 +154,8 @@ void SensorLogger::processCommand(const String& command) {
     sendLog();
   } else if (command == "CLEAR_LOG") {
     clearLog();
-    bluetooth_.println("OK_CLEARED");
+    txCharacteristic_->setValue("OK_CLEARED\n");
+    txCharacteristic_->notify();
   } else if (command.startsWith("TIME:")) {
     unsigned long epoch = command.substring(5).toInt();
     unsigned int year;
@@ -114,28 +178,45 @@ void SensorLogger::processCommand(const String& command) {
     if (epoch != 0) {
       epochOffset_ = epoch - millis() / 1000UL;
       timeSynchronized_ = true;
-      bluetooth_.println("OK_TIME");
+      txCharacteristic_->setValue("OK_TIME\n");
+      txCharacteristic_->notify();
     } else {
-      bluetooth_.println("ERROR_TIME");
+      txCharacteristic_->setValue("ERROR_TIME\n");
+      txCharacteristic_->notify();
     }
   }
 }
 
 void SensorLogger::sendLog() {
-  bluetooth_.println("timestamp,temp,humid,light,soil,device");
+  sendNotification("timestamp,temp,humid,light,soil,device\n");
   for (size_t index = 0; index < logCount_; ++index) {
     size_t logIndex = (logStart_ + index) % kMaxLogEntries;
     const SensorReading& reading = log_[logIndex];
-    bluetooth_.printf("%lu,%.2f,%.2f,%.2f,%u,%s\n",
+    char line[128];
+    snprintf(line, sizeof(line), "%lu,%.2f,%.2f,%.2f,%u,%s\n",
       reading.timestamp,
       reading.temperature,
       reading.humidity,
       reading.illuminance,
       reading.soilMoisture,
-      bluetoothName_);
+      bluetoothName_.c_str());
+    sendNotification(line);
     delay(20);
   }
-  bluetooth_.println("END_LOG");
+  sendNotification("END_LOG\n");
+}
+
+void SensorLogger::sendNotification(const char* data) {
+  constexpr size_t kNotificationSize = 20;
+  uint8_t notification[kNotificationSize];
+  size_t length = strlen(data);
+  for (size_t offset = 0; offset < length; offset += kNotificationSize) {
+    size_t chunkSize = min(kNotificationSize, length - offset);
+    memcpy(notification, data + offset, chunkSize);
+    txCharacteristic_->setValue(notification, chunkSize);
+    txCharacteristic_->notify();
+    delay(10);
+  }
 }
 
 void SensorLogger::clearLog() {
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
index 482cd3a..0ad9f42 100644
--- a/firmware/SensorLogger.h
+++ b/firmware/SensorLogger.h
@@ -1,7 +1,9 @@
 #pragma once
 
 #include <Arduino.h>
-#include <BluetoothSerial.h>
+
+class BLECharacteristic;
+class BLEServer;
 
 struct SensorReading {
   unsigned long timestamp;
@@ -15,7 +17,7 @@ class SensorLogger {
 public:
   static constexpr size_t kMaxLogEntries = 2000;
 
-  void begin(uint8_t soilPin, const char* bluetoothName);
+  void begin(uint8_t soilPin);
   bool update();
   const SensorReading& latest() const;
   bool hasReading() const;
@@ -26,11 +28,14 @@ private:
   void readAndStore();
   void processBluetooth();
   void processCommand(const String& command);
+  void receiveBluetoothData(const String& data);
+  void sendNotification(const char* data);
   void sendLog();
   void clearLog();
   unsigned long currentTimestamp() const;
 
-  BluetoothSerial bluetooth_;
+  BLEServer* server_ = nullptr;
+  BLECharacteristic* txCharacteristic_ = nullptr;
   SensorReading log_[kMaxLogEntries] = {};
   SensorReading latest_ = {};
   size_t logStart_ = 0;
@@ -39,6 +44,8 @@ private:
   unsigned long lastMeasure_ = 0;
   unsigned long epochOffset_ = 0;
   bool timeSynchronized_ = false;
-  const char* bluetoothName_ = "";
+  String bluetoothName_;
   String commandBuffer_;
+
+  friend class SensorLoggerCallbacks;
 };
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 5dab087..8754b3d 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -123,7 +123,7 @@ void setup() {
   u8g2.begin();
   u8g2.enableUTF8Print(); // UTF-8（日本語）描画を有効化
 
-  sensorLogger.begin(32, kBluetoothName);
+  sensorLogger.begin(32);
   updateDisplay();
 
   // I2S ピン設定 (BCK: 27, WS: 25, DOUT: 26)

From 5e052dba930be6288f38af2af03e155b093bb5e4 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 17:24:08 +0900
Subject: [PATCH 10/18] =?UTF-8?q?RTC=E8=A1=A8=E7=A4=BA?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/SensorLogger.cpp | 53 ++++++++++++++++++++++++++++++++++++---
 firmware/SensorLogger.h   |  8 +++---
 firmware/firmware.ino     | 40 ++++++++++++++++++++++-------
 3 files changed, 86 insertions(+), 15 deletions(-)

diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index 8bd63bd..90a7061 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -12,11 +12,17 @@ namespace {
 constexpr char kNusServiceUuid[] = "6E400001-B5A3-F393-E0A9-E50E24DCCA9E";
 constexpr char kNusRxUuid[] = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E";
 constexpr char kNusTxUuid[] = "6E400003-B5A3-F393-E0A9-E50E24DCCA9E";
+constexpr int64_t kInitialYear = 1700;
+constexpr int64_t kSecondsPerDay = 86400;
 
 Adafruit_AHTX0 aht20;
 BH1750 bh1750;
 bool aht20Ready = false;
 bool bh1750Ready = false;
+
+bool isLeapYear(int year) {
+  return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
+}
 }
 
 class SensorLoggerCallbacks : public BLECharacteristicCallbacks {
@@ -96,6 +102,47 @@ bool SensorLogger::hasReading() const {
   return logCount_ != 0;
 }
 
+size_t SensorLogger::logCount() const {
+  return logCount_;
+}
+
+bool SensorLogger::getCurrentTime(char* buffer, size_t bufferSize) const {
+  if (bufferSize == 0) {
+    return false;
+  }
+
+  int64_t timestamp = currentTimestamp();
+  if (timeSynchronized_) {
+    time_t unixTimestamp = static_cast<time_t>(timestamp);
+    struct tm date;
+    localtime_r(&unixTimestamp, &date);
+    strftime(buffer, bufferSize, "%Y/%m/%d %H:%M:%S", &date);
+    return true;
+  }
+
+  int year = static_cast<int>(kInitialYear);
+  int month = 1;
+  int day = 1;
+  int64_t days = timestamp / kSecondsPerDay;
+  int seconds = static_cast<int>(timestamp % kSecondsPerDay);
+  while (days >= (isLeapYear(year) ? 366 : 365)) {
+    days -= isLeapYear(year) ? 366 : 365;
+    ++year;
+  }
+  const int daysInMonth[] = {
+    31, isLeapYear(year) ? 29 : 28, 31, 30, 31, 30,
+    31, 31, 30, 31, 30, 31
+  };
+  while (days >= daysInMonth[month - 1]) {
+    days -= daysInMonth[month - 1];
+    ++month;
+  }
+  day += static_cast<int>(days);
+  snprintf(buffer, bufferSize, "%04d/%02d/%02d %02d:%02d:%02d",
+    year, month, day, seconds / 3600, (seconds / 60) % 60, seconds % 60);
+  return true;
+}
+
 void SensorLogger::readAndStore() {
   sensors_event_t humidityEvent;
   sensors_event_t temperatureEvent;
@@ -193,7 +240,7 @@ void SensorLogger::sendLog() {
     size_t logIndex = (logStart_ + index) % kMaxLogEntries;
     const SensorReading& reading = log_[logIndex];
     char line[128];
-    snprintf(line, sizeof(line), "%lu,%.2f,%.2f,%.2f,%u,%s\n",
+    snprintf(line, sizeof(line), "%lld,%.2f,%.2f,%.2f,%u,%s\n",
       reading.timestamp,
       reading.temperature,
       reading.humidity,
@@ -224,7 +271,7 @@ void SensorLogger::clearLog() {
   logCount_ = 0;
 }
 
-unsigned long SensorLogger::currentTimestamp() const {
-  unsigned long elapsedSeconds = millis() / 1000UL;
+int64_t SensorLogger::currentTimestamp() const {
+  int64_t elapsedSeconds = millis() / 1000UL;
   return timeSynchronized_ ? epochOffset_ + elapsedSeconds : elapsedSeconds;
 }
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
index 0ad9f42..adfe885 100644
--- a/firmware/SensorLogger.h
+++ b/firmware/SensorLogger.h
@@ -6,7 +6,7 @@ class BLECharacteristic;
 class BLEServer;
 
 struct SensorReading {
-  unsigned long timestamp;
+  int64_t timestamp;
   float temperature;
   float humidity;
   float illuminance;
@@ -21,6 +21,8 @@ public:
   bool update();
   const SensorReading& latest() const;
   bool hasReading() const;
+  size_t logCount() const;
+  bool getCurrentTime(char* buffer, size_t bufferSize) const;
 
 private:
   static constexpr unsigned long kMeasureIntervalMs = 3600000UL;
@@ -32,7 +34,7 @@ private:
   void sendNotification(const char* data);
   void sendLog();
   void clearLog();
-  unsigned long currentTimestamp() const;
+  int64_t currentTimestamp() const;
 
   BLEServer* server_ = nullptr;
   BLECharacteristic* txCharacteristic_ = nullptr;
@@ -42,7 +44,7 @@ private:
   size_t logCount_ = 0;
   uint8_t soilPin_ = 0;
   unsigned long lastMeasure_ = 0;
-  unsigned long epochOffset_ = 0;
+  int64_t epochOffset_ = 0;
   bool timeSynchronized_ = false;
   String bluetoothName_;
   String commandBuffer_;
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 8754b3d..177b172 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -4,7 +4,7 @@
 #include "NeoPixelController.h"
 #include "SensorLogger.h"
 
-const char kBluetoothName[] = "BT_Speaker5.32";
+const char kBluetoothName[] = "BT_Speaker5.4";
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
@@ -18,25 +18,37 @@ String currentTitle = "未接続";
 String currentArtist = "";
 int currentVolumePercent = 0; // 音量 (0 ~ 100%)
 bool bluetoothConnected = false;
+bool musicPlaying = false;
+unsigned long lastDisplayUpdate = 0;
 
 // 画面全体を再描画する関数
 void updateDisplay() {
   u8g2.clearBuffer();
 
-  if (!bluetoothConnected) {
+  if (!bluetoothConnected || !musicPlaying) {
     u8g2.setFont(u8g2_font_6x10_tf);
     const SensorReading& reading = sensorLogger.latest();
 
     char sensorLine[32];
+    char timeLine[24];
+    if (sensorLogger.getCurrentTime(timeLine, sizeof(timeLine))) {
+      u8g2.drawStr(0, 9, timeLine);
+    } else {
+      u8g2.drawStr(0, 9, "RTC: --/--/-- --:--:--");
+    }
+
+    snprintf(sensorLine, sizeof(sensorLine), "Log: %u", static_cast<unsigned int>(sensorLogger.logCount()));
+    u8g2.drawStr(0, 20, sensorLine);
+
     snprintf(sensorLine, sizeof(sensorLine), "T:%5.1fC H:%5.1f%%",
       reading.temperature, reading.humidity);
-    u8g2.drawStr(0, 12, sensorLine);
+    u8g2.drawStr(0, 32, sensorLine);
 
     snprintf(sensorLine, sizeof(sensorLine), "Light: %6.1f lx", reading.illuminance);
-    u8g2.drawStr(0, 30, sensorLine);
+    u8g2.drawStr(0, 44, sensorLine);
 
     snprintf(sensorLine, sizeof(sensorLine), "Soil: %4u", reading.soilMoisture);
-    u8g2.drawStr(0, 48, sensorLine);
+    u8g2.drawStr(0, 56, sensorLine);
     u8g2.sendBuffer();
     return;
   }
@@ -88,7 +100,7 @@ void avrc_metadata_callback(uint8_t id, const uint8_t *text) {
     updated = true;
   }
 
-  if (updated && bluetoothConnected) {
+  if (updated && bluetoothConnected && musicPlaying) {
     updateDisplay();
   }
 }
@@ -96,17 +108,22 @@ void avrc_metadata_callback(uint8_t id, const uint8_t *text) {
 // 音量変更時のコールバック関数
 void volume_changed_callback(int volume) {
   currentVolumePercent = map(volume, 0, 127, 0, 100);
-  if (bluetoothConnected) {
+  if (bluetoothConnected && musicPlaying) {
     updateDisplay();
   }
 }
 
 void audio_state_changed_callback(esp_a2d_audio_state_t state, void *) {
-  neoPixelController.setPlaying(state == ESP_A2D_AUDIO_STATE_STARTED);
+  musicPlaying = state == ESP_A2D_AUDIO_STATE_STARTED;
+  neoPixelController.setPlaying(musicPlaying);
+  updateDisplay();
 }
 
 void connection_state_changed_callback(esp_a2d_connection_state_t state, void *) {
   bluetoothConnected = state == ESP_A2D_CONNECTION_STATE_CONNECTED;
+  if (!bluetoothConnected) {
+    musicPlaying = false;
+  }
   updateDisplay();
 }
 
@@ -125,6 +142,7 @@ void setup() {
 
   sensorLogger.begin(32);
   updateDisplay();
+  lastDisplayUpdate = millis();
 
   // I2S ピン設定 (BCK: 27, WS: 25, DOUT: 26)
   i2s_pin_config_t my_pin_config = {
@@ -148,7 +166,11 @@ void setup() {
 
 void loop() {
   neoPixelController.update();
-  if (sensorLogger.update() && !bluetoothConnected) {
+  bool newReading = sensorLogger.update();
+  unsigned long now = millis();
+  if ((!bluetoothConnected || !musicPlaying)
+      && (newReading || now - lastDisplayUpdate >= 1000UL)) {
+    lastDisplayUpdate = now;
     updateDisplay();
   }
 }
\ No newline at end of file

From 787f236fc66abde1da84a390c1c20033e9158c62 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 18:33:22 +0900
Subject: [PATCH 11/18] =?UTF-8?q?BLE=E5=BA=83=E5=91=8A=E5=90=8D?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/SensorLogger.cpp | 38 ++++++++++++++++++++++++++++++++++++--
 firmware/SensorLogger.h   |  5 +++++
 firmware/firmware.ino     | 21 +++++++++++++++------
 3 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index 90a7061..8ef22f3 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -39,11 +39,19 @@ private:
 
 class SensorLoggerServerCallbacks : public BLEServerCallbacks {
 public:
-  void onConnect(BLEServer*) override {}
+  explicit SensorLoggerServerCallbacks(SensorLogger* logger) : logger_(logger) {}
+
+  void onConnect(BLEServer*) override {
+    logger_->bluetoothConnected_ = true;
+  }
 
   void onDisconnect(BLEServer* server) override {
+    logger_->bluetoothConnected_ = false;
     server->startAdvertising();
   }
+
+private:
+  SensorLogger* logger_;
 };
 
 void SensorLogger::begin(uint8_t soilPin) {
@@ -61,7 +69,7 @@ void SensorLogger::begin(uint8_t soilPin) {
   BLEDevice::init(bluetoothName_.c_str());
 
   server_ = BLEDevice::createServer();
-  server_->setCallbacks(new SensorLoggerServerCallbacks());
+  server_->setCallbacks(new SensorLoggerServerCallbacks(this));
   BLEService* service = server_->createService(kNusServiceUuid);
   BLECharacteristic* rxCharacteristic = service->createCharacteristic(
     kNusRxUuid, BLECharacteristic::PROPERTY_WRITE | BLECharacteristic::PROPERTY_WRITE_NR);
@@ -94,6 +102,24 @@ bool SensorLogger::update() {
   return false;
 }
 
+void SensorLogger::refreshSensors() {
+  SensorReading reading = {};
+  sensors_event_t humidityEvent;
+  sensors_event_t temperatureEvent;
+
+  if (aht20Ready) {
+    aht20.getEvent(&humidityEvent, &temperatureEvent);
+    reading.temperature = temperatureEvent.temperature;
+    reading.humidity = humidityEvent.relative_humidity;
+  }
+  if (bh1750Ready) {
+    reading.illuminance = bh1750.readLightLevel();
+  }
+  reading.soilMoisture = analogRead(soilPin_);
+  reading.timestamp = latest_.timestamp;
+  latest_ = reading;
+}
+
 const SensorReading& SensorLogger::latest() const {
   return latest_;
 }
@@ -102,6 +128,14 @@ bool SensorLogger::hasReading() const {
   return logCount_ != 0;
 }
 
+const char* SensorLogger::bluetoothName() const {
+  return bluetoothName_.c_str();
+}
+
+bool SensorLogger::isBluetoothConnected() const {
+  return bluetoothConnected_;
+}
+
 size_t SensorLogger::logCount() const {
   return logCount_;
 }
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
index adfe885..fedfff1 100644
--- a/firmware/SensorLogger.h
+++ b/firmware/SensorLogger.h
@@ -19,10 +19,13 @@ public:
 
   void begin(uint8_t soilPin);
   bool update();
+  void refreshSensors();
   const SensorReading& latest() const;
   bool hasReading() const;
   size_t logCount() const;
   bool getCurrentTime(char* buffer, size_t bufferSize) const;
+  const char* bluetoothName() const;
+  bool isBluetoothConnected() const;
 
 private:
   static constexpr unsigned long kMeasureIntervalMs = 3600000UL;
@@ -46,8 +49,10 @@ private:
   unsigned long lastMeasure_ = 0;
   int64_t epochOffset_ = 0;
   bool timeSynchronized_ = false;
+  bool bluetoothConnected_ = false;
   String bluetoothName_;
   String commandBuffer_;
 
   friend class SensorLoggerCallbacks;
+  friend class SensorLoggerServerCallbacks;
 };
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 177b172..37f25b0 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -31,24 +31,32 @@ void updateDisplay() {
 
     char sensorLine[32];
     char timeLine[24];
+    if (sensorLogger.isBluetoothConnected()) {
+      u8g2.setDrawColor(1);
+      u8g2.drawBox(0, 0, 128, 10);
+      u8g2.setDrawColor(0);
+    }
+    u8g2.drawStr(0, 9, sensorLogger.bluetoothName());
+    u8g2.setDrawColor(1);
+
     if (sensorLogger.getCurrentTime(timeLine, sizeof(timeLine))) {
-      u8g2.drawStr(0, 9, timeLine);
+      u8g2.drawStr(0, 20, timeLine);
     } else {
-      u8g2.drawStr(0, 9, "RTC: --/--/-- --:--:--");
+      u8g2.drawStr(0, 20, "RTC: --/--/-- --:--:--");
     }
 
     snprintf(sensorLine, sizeof(sensorLine), "Log: %u", static_cast<unsigned int>(sensorLogger.logCount()));
-    u8g2.drawStr(0, 20, sensorLine);
+    u8g2.drawStr(0, 31, sensorLine);
 
     snprintf(sensorLine, sizeof(sensorLine), "T:%5.1fC H:%5.1f%%",
       reading.temperature, reading.humidity);
-    u8g2.drawStr(0, 32, sensorLine);
+    u8g2.drawStr(0, 42, sensorLine);
 
     snprintf(sensorLine, sizeof(sensorLine), "Light: %6.1f lx", reading.illuminance);
-    u8g2.drawStr(0, 44, sensorLine);
+    u8g2.drawStr(0, 53, sensorLine);
 
     snprintf(sensorLine, sizeof(sensorLine), "Soil: %4u", reading.soilMoisture);
-    u8g2.drawStr(0, 56, sensorLine);
+    u8g2.drawStr(0, 64, sensorLine);
     u8g2.sendBuffer();
     return;
   }
@@ -171,6 +179,7 @@ void loop() {
   if ((!bluetoothConnected || !musicPlaying)
       && (newReading || now - lastDisplayUpdate >= 1000UL)) {
     lastDisplayUpdate = now;
+    sensorLogger.refreshSensors();
     updateDisplay();
   }
 }
\ No newline at end of file

From e83a7cff8030524f9cf524ee4cb3a0c94877be9a Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 19:40:21 +0900
Subject: [PATCH 12/18] =?UTF-8?q?=E3=82=BF=E3=82=A4=E3=83=A0=E3=82=B9?=
 =?UTF-8?q?=E3=82=BF=E3=83=B3=E3=83=97=E8=AA=BF=E6=95=B4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/SensorLogger.cpp | 48 +++++++++++++++++++++++++++++++++------
 firmware/SensorLogger.h   |  8 ++++++-
 2 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index 8ef22f3..98ee1d6 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -47,6 +47,8 @@ public:
 
   void onDisconnect(BLEServer* server) override {
     logger_->bluetoothConnected_ = false;
+    logger_->commandBuffer_ = "";
+    logger_->lastAdvertise_ = millis();
     server->startAdvertising();
   }
 
@@ -88,12 +90,18 @@ void SensorLogger::begin(uint8_t soilPin) {
 
   readAndStore();
   lastMeasure_ = millis();
+  lastAdvertise_ = millis();
 }
 
 bool SensorLogger::update() {
   processBluetooth();
 
   unsigned long now = millis();
+  if (!bluetoothConnected_ && now - lastAdvertise_ >= kAdvertiseRetryIntervalMs) {
+    lastAdvertise_ = now;
+    BLEDevice::startAdvertising();
+  }
+
   if (now - lastMeasure_ >= kMeasureIntervalMs) {
     lastMeasure_ = now;
     readAndStore();
@@ -140,12 +148,11 @@ size_t SensorLogger::logCount() const {
   return logCount_;
 }
 
-bool SensorLogger::getCurrentTime(char* buffer, size_t bufferSize) const {
+bool SensorLogger::formatTimestamp(int64_t timestamp, char* buffer, size_t bufferSize) const {
   if (bufferSize == 0) {
     return false;
   }
 
-  int64_t timestamp = currentTimestamp();
   if (timeSynchronized_) {
     time_t unixTimestamp = static_cast<time_t>(timestamp);
     struct tm date;
@@ -177,6 +184,10 @@ bool SensorLogger::getCurrentTime(char* buffer, size_t bufferSize) const {
   return true;
 }
 
+bool SensorLogger::getCurrentTime(char* buffer, size_t bufferSize) const {
+  return formatTimestamp(currentTimestamp(), buffer, bufferSize);
+}
+
 void SensorLogger::readAndStore() {
   sensors_event_t humidityEvent;
   sensors_event_t temperatureEvent;
@@ -230,6 +241,23 @@ void SensorLogger::receiveBluetoothData(const String& data) {
   }
 }
 
+void SensorLogger::applyHistoricalTimeAdjustment(int64_t epoch) {
+  if (historicalAdjustmentApplied_ || timeSynchronized_) {
+    return;
+  }
+
+  const int64_t elapsedSeconds = millis() / 1000UL;
+  historicalEpochOffset_ = epoch - elapsedSeconds;
+  for (size_t index = 0; index < logCount_; ++index) {
+    size_t logIndex = (logStart_ + index) % kMaxLogEntries;
+    const int64_t storedSeconds = log_[logIndex].timestamp;
+    if (storedSeconds <= elapsedSeconds) {
+      log_[logIndex].timestamp = storedSeconds + historicalEpochOffset_;
+    }
+  }
+  historicalAdjustmentApplied_ = true;
+}
+
 void SensorLogger::processCommand(const String& command) {
   if (command == "GET_LOG") {
     sendLog();
@@ -257,6 +285,7 @@ void SensorLogger::processCommand(const String& command) {
       epoch = static_cast<unsigned long>(mktime(&date));
     }
     if (epoch != 0) {
+      applyHistoricalTimeAdjustment(static_cast<int64_t>(epoch));
       epochOffset_ = epoch - millis() / 1000UL;
       timeSynchronized_ = true;
       txCharacteristic_->setValue("OK_TIME\n");
@@ -269,17 +298,22 @@ void SensorLogger::processCommand(const String& command) {
 }
 
 void SensorLogger::sendLog() {
-  sendNotification("timestamp,temp,humid,light,soil,device\n");
+  sendNotification("タイムスタンプ,温度,湿度,土壌水分,光量,デバイス名\n");
   for (size_t index = 0; index < logCount_; ++index) {
     size_t logIndex = (logStart_ + index) % kMaxLogEntries;
     const SensorReading& reading = log_[logIndex];
-    char line[128];
-    snprintf(line, sizeof(line), "%lld,%.2f,%.2f,%.2f,%u,%s\n",
-      reading.timestamp,
+    char timestamp[32];
+    char line[160];
+    const bool timestampValid = formatTimestamp(reading.timestamp, timestamp, sizeof(timestamp));
+    if (!timestampValid) {
+      timestamp[0] = '\0';
+    }
+    snprintf(line, sizeof(line), "%s,%.2f,%.2f,%u,%.2f,%s\n",
+      timestamp,
       reading.temperature,
       reading.humidity,
-      reading.illuminance,
       reading.soilMoisture,
+      reading.illuminance,
       bluetoothName_.c_str());
     sendNotification(line);
     delay(20);
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
index fedfff1..67d3ad2 100644
--- a/firmware/SensorLogger.h
+++ b/firmware/SensorLogger.h
@@ -24,11 +24,13 @@ public:
   bool hasReading() const;
   size_t logCount() const;
   bool getCurrentTime(char* buffer, size_t bufferSize) const;
+  bool formatTimestamp(int64_t timestamp, char* buffer, size_t bufferSize) const;
   const char* bluetoothName() const;
   bool isBluetoothConnected() const;
 
 private:
-  static constexpr unsigned long kMeasureIntervalMs = 3600000UL;
+  static constexpr unsigned long kMeasureIntervalMs = 10000UL;
+  static constexpr unsigned long kAdvertiseRetryIntervalMs = 500UL;
 
   void readAndStore();
   void processBluetooth();
@@ -37,6 +39,7 @@ private:
   void sendNotification(const char* data);
   void sendLog();
   void clearLog();
+  void applyHistoricalTimeAdjustment(int64_t epoch);
   int64_t currentTimestamp() const;
 
   BLEServer* server_ = nullptr;
@@ -47,8 +50,11 @@ private:
   size_t logCount_ = 0;
   uint8_t soilPin_ = 0;
   unsigned long lastMeasure_ = 0;
+  unsigned long lastAdvertise_ = 0;
   int64_t epochOffset_ = 0;
+  int64_t historicalEpochOffset_ = 0;
   bool timeSynchronized_ = false;
+  bool historicalAdjustmentApplied_ = false;
   bool bluetoothConnected_ = false;
   String bluetoothName_;
   String commandBuffer_;

From ae692f67af13d9d3b1e3db282716c743f6f2b38c Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 19:51:29 +0900
Subject: [PATCH 13/18] =?UTF-8?q?CSV=E4=BF=9D=E5=AD=98=E8=AA=BF=E6=95=B4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/SensorLogger.cpp | 4 ++--
 firmware/SensorLogger.h   | 2 +-
 firmware/firmware.ino     | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index 98ee1d6..58bf167 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -12,6 +12,7 @@ namespace {
 constexpr char kNusServiceUuid[] = "6E400001-B5A3-F393-E0A9-E50E24DCCA9E";
 constexpr char kNusRxUuid[] = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E";
 constexpr char kNusTxUuid[] = "6E400003-B5A3-F393-E0A9-E50E24DCCA9E";
+constexpr char kBleDeviceNamePrefix[] = "EnvLog";
 constexpr int64_t kInitialYear = 1700;
 constexpr int64_t kSecondsPerDay = 86400;
 
@@ -66,7 +67,7 @@ void SensorLogger::begin(uint8_t soilPin) {
 
   uint64_t mac = ESP.getEfuseMac();
   char name[14];
-  snprintf(name, sizeof(name), "EnvLog-%05llX", mac & 0xFFFFF);
+  snprintf(name, sizeof(name), "%s-%05llX", kBleDeviceNamePrefix, mac & 0xFFFFF);
   bluetoothName_ = name;
   BLEDevice::init(bluetoothName_.c_str());
 
@@ -298,7 +299,6 @@ void SensorLogger::processCommand(const String& command) {
 }
 
 void SensorLogger::sendLog() {
-  sendNotification("タイムスタンプ,温度,湿度,土壌水分,光量,デバイス名\n");
   for (size_t index = 0; index < logCount_; ++index) {
     size_t logIndex = (logStart_ + index) % kMaxLogEntries;
     const SensorReading& reading = log_[logIndex];
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
index 67d3ad2..8710819 100644
--- a/firmware/SensorLogger.h
+++ b/firmware/SensorLogger.h
@@ -29,7 +29,7 @@ public:
   bool isBluetoothConnected() const;
 
 private:
-  static constexpr unsigned long kMeasureIntervalMs = 10000UL;
+  static constexpr unsigned long kMeasureIntervalMs = 3600000UL;
   static constexpr unsigned long kAdvertiseRetryIntervalMs = 500UL;
 
   void readAndStore();
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 37f25b0..d974a8e 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -4,7 +4,7 @@
 #include "NeoPixelController.h"
 #include "SensorLogger.h"
 
-const char kBluetoothName[] = "BT_Speaker5.4";
+const char kA2dpDeviceName[] = "BT_Speaker5.4";
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
@@ -169,7 +169,7 @@ void setup() {
   a2dp_sink.set_on_connection_state_changed(connection_state_changed_callback);
 
   // Bluetooth起動
-  a2dp_sink.start(kBluetoothName);
+  a2dp_sink.start(kA2dpDeviceName);
 }
 
 void loop() {

From c6ffbacb0370c431184569a2c597460a94527e0c Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 20:38:31 +0900
Subject: [PATCH 14/18] =?UTF-8?q?=E5=AE=8C=E6=88=90?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/SensorLogger.cpp | 3 +++
 firmware/firmware.ino     | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index 58bf167..c6958b3 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -85,6 +85,9 @@ void SensorLogger::begin(uint8_t soilPin) {
   BLEAdvertising* advertising = BLEDevice::getAdvertising();
   advertising->addServiceUUID(kNusServiceUuid);
   advertising->setScanResponse(true);
+  BLEAdvertisementData scanResponseData;
+  scanResponseData.setName(bluetoothName_.c_str());
+  advertising->setScanResponseData(scanResponseData);
   advertising->setMinPreferred(0x06);
   advertising->setMinPreferred(0x12);
   BLEDevice::startAdvertising();
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index d974a8e..164f065 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -4,7 +4,7 @@
 #include "NeoPixelController.h"
 #include "SensorLogger.h"
 
-const char kA2dpDeviceName[] = "BT_Speaker5.4";
+const char kA2dpDeviceName[] = "BT_Speaker5.5";
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);

From e7f9fb4c1b12bbfd62b2906a758a1732cba625d0 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 20:43:53 +0900
Subject: [PATCH 15/18] =?UTF-8?q?=E3=82=B3=E3=83=A1=E3=83=B3=E3=83=88?=
 =?UTF-8?q?=E3=82=92=E8=BF=BD=E5=8A=A0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/NeoPixelController.cpp |  8 +++++
 firmware/NeoPixelController.h   |  7 ++++
 firmware/SensorLogger.cpp       | 38 ++++++++++++++++++++
 firmware/SensorLogger.h         | 55 ++++++++++++++++++-----------
 firmware/firmware.ino           | 62 ++++++++++++++++++---------------
 5 files changed, 120 insertions(+), 50 deletions(-)

diff --git a/firmware/NeoPixelController.cpp b/firmware/NeoPixelController.cpp
index 5624ebb..4e77f5f 100644
--- a/firmware/NeoPixelController.cpp
+++ b/firmware/NeoPixelController.cpp
@@ -3,7 +3,9 @@
 #include <Adafruit_NeoPixel.h>
 
 namespace {
+// 今回は1個のNeoPixelを使います。
 constexpr uint16_t kCount = 1;
+// 音楽再生中に順番に表示する色です。値はRGBの順です。
 constexpr uint32_t kColors[] = {
   0xFF0000, 0xFF8000, 0xFFFF00, 0x00FF00,
   0x0000FF, 0x4B0082, 0x8F00FF
@@ -14,6 +16,7 @@ Adafruit_NeoPixel pixels(kCount, 0, NEO_GRB + NEO_KHZ800);
 }
 
 void NeoPixelController::begin(uint8_t pin) {
+  // LEDの接続先と明るさを設定し、停止中の色を表示します。
   pixels.setPin(pin);
   pixels.begin();
   pixels.setBrightness(255);
@@ -25,17 +28,20 @@ void NeoPixelController::setPlaying(bool playing) {
   isPlaying_ = playing;
 
   if (isPlaying_) {
+    // 再生開始時刻を記録します。ここから色の変化を始めます。
     transitionStart_ = millis();
     lastUpdate_ = transitionStart_;
     return;
   }
 
+  // 停止中は、決めておいた色に戻します。
   colorIndex_ = kStoppedColorIndex;
   pixels.setPixelColor(0, kColors[colorIndex_]);
   pixels.show();
 }
 
 void NeoPixelController::update() {
+  // 再生中でない、または更新間隔が短すぎるときは何もしません。
   if (!isPlaying_ || millis() - lastUpdate_ < kUpdateIntervalMs) {
     return;
   }
@@ -44,6 +50,7 @@ void NeoPixelController::update() {
   lastUpdate_ = now;
   unsigned long transitionElapsed = now - transitionStart_;
   if (transitionElapsed >= kTransitionMs) {
+    // 色の切り替えが終わったら、次の色へ進みます。
     colorIndex_ = (colorIndex_ + transitionElapsed / kTransitionMs) % kColorCount;
     transitionStart_ = now;
     transitionElapsed = 0;
@@ -52,6 +59,7 @@ void NeoPixelController::update() {
   uint8_t nextColorIndex = (colorIndex_ + 1) % kColorCount;
   uint32_t currentColor = kColors[colorIndex_];
   uint32_t nextColor = kColors[nextColorIndex];
+  // 現在の色と次の色を混ぜることで、急に変わらず滑らかに変化させます。
   uint8_t red = ((currentColor >> 16) * (kTransitionMs - transitionElapsed)
     + (nextColor >> 16) * transitionElapsed) / kTransitionMs;
   uint8_t green = (((currentColor >> 8) & 0xFF) * (kTransitionMs - transitionElapsed)
diff --git a/firmware/NeoPixelController.h b/firmware/NeoPixelController.h
index f091f81..29b4b20 100644
--- a/firmware/NeoPixelController.h
+++ b/firmware/NeoPixelController.h
@@ -4,15 +4,22 @@
 
 class NeoPixelController {
 public:
+  // NeoPixelを使い始める準備をします。
   void begin(uint8_t pin);
+  // 音楽再生中かどうかを設定します。
   void setPlaying(bool playing);
+  // 時間の経過に合わせてLEDを更新します。
   void update();
 
 private:
+  // 音楽停止中に表示する色（配列の4番目、緑）です。
   static constexpr uint8_t kStoppedColorIndex = 3;
+  // 色を計算する間隔です。短いほどなめらかになります。
   static constexpr unsigned long kUpdateIntervalMs = 30;
+  // 1色から次の色へ変わる時間です。
   static constexpr unsigned long kTransitionMs = 3000;
 
+  // 現在のLEDの状態を保存します。
   bool isPlaying_ = false;
   uint8_t colorIndex_ = 0;
   unsigned long lastUpdate_ = 0;
diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index c6958b3..ee9f35d 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -9,6 +9,8 @@
 #include <time.h>
 
 namespace {
+// BLEサービスと、その中の2本の通信路を識別する番号です。
+// UUIDは、Bluetooth上で機能を区別するための長い名前です。
 constexpr char kNusServiceUuid[] = "6E400001-B5A3-F393-E0A9-E50E24DCCA9E";
 constexpr char kNusRxUuid[] = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E";
 constexpr char kNusTxUuid[] = "6E400003-B5A3-F393-E0A9-E50E24DCCA9E";
@@ -16,21 +18,25 @@ constexpr char kBleDeviceNamePrefix[] = "EnvLog";
 constexpr int64_t kInitialYear = 1700;
 constexpr int64_t kSecondsPerDay = 86400;
 
+// センサー本体と、センサーが使える状態かどうかを保存します。
 Adafruit_AHTX0 aht20;
 BH1750 bh1750;
 bool aht20Ready = false;
 bool bh1750Ready = false;
 
 bool isLeapYear(int year) {
+  // 4年ごと。ただし100年ごとは除き、400年ごとはうるう年です。
   return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
 }
 }
 
+// BLEの受信側の処理です。アプリがデータを書き込むと呼ばれます。
 class SensorLoggerCallbacks : public BLECharacteristicCallbacks {
 public:
   explicit SensorLoggerCallbacks(SensorLogger* logger) : logger_(logger) {}
 
   void onWrite(BLECharacteristic* characteristic) override {
+    // 受信した文字をSensorLoggerへ渡します。
     logger_->receiveBluetoothData(characteristic->getValue().c_str());
   }
 
@@ -38,15 +44,18 @@ private:
   SensorLogger* logger_;
 };
 
+// BLEの接続と切断を知らせる処理です。
 class SensorLoggerServerCallbacks : public BLEServerCallbacks {
 public:
   explicit SensorLoggerServerCallbacks(SensorLogger* logger) : logger_(logger) {}
 
   void onConnect(BLEServer*) override {
+    // 接続中は、画面に接続中であることを表示できます。
     logger_->bluetoothConnected_ = true;
   }
 
   void onDisconnect(BLEServer* server) override {
+    // 切断されたら、次の接続を待つために広告を再開します。
     logger_->bluetoothConnected_ = false;
     logger_->commandBuffer_ = "";
     logger_->lastAdvertise_ = millis();
@@ -58,33 +67,41 @@ private:
 };
 
 void SensorLogger::begin(uint8_t soilPin) {
+  // センサーとBLE通信を使い始めるための初期設定です。
   soilPin_ = soilPin;
   pinMode(soilPin_, INPUT);
   analogReadResolution(12);
 
+  // センサーの初期化に成功したかを保存します。
   aht20Ready = aht20.begin();
   bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
 
+  // ESP32固有の番号を名前に加え、同じ名前の機器と区別します。
   uint64_t mac = ESP.getEfuseMac();
   char name[14];
   snprintf(name, sizeof(name), "%s-%05llX", kBleDeviceNamePrefix, mac & 0xFFFFF);
   bluetoothName_ = name;
   BLEDevice::init(bluetoothName_.c_str());
 
+  // BLEサーバーと、センサー通信用のサービスを作ります。
   server_ = BLEDevice::createServer();
   server_->setCallbacks(new SensorLoggerServerCallbacks(this));
   BLEService* service = server_->createService(kNusServiceUuid);
+  // RXはアプリからESP32へ命令を送る通路です。
   BLECharacteristic* rxCharacteristic = service->createCharacteristic(
     kNusRxUuid, BLECharacteristic::PROPERTY_WRITE | BLECharacteristic::PROPERTY_WRITE_NR);
   rxCharacteristic->setCallbacks(new SensorLoggerCallbacks(this));
+  // TXはESP32からアプリへログを送る通路です。
   txCharacteristic_ = service->createCharacteristic(
     kNusTxUuid, BLECharacteristic::PROPERTY_NOTIFY);
   txCharacteristic_->addDescriptor(new BLE2902());
   service->start();
 
+  // BLE広告は「この機器が近くにいます」と周囲へ知らせる仕組みです。
   BLEAdvertising* advertising = BLEDevice::getAdvertising();
   advertising->addServiceUUID(kNusServiceUuid);
   advertising->setScanResponse(true);
+  // A2DP開始後に共通のBluetooth名が変わっても、BLE名を返せるようにします。
   BLEAdvertisementData scanResponseData;
   scanResponseData.setName(bluetoothName_.c_str());
   advertising->setScanResponseData(scanResponseData);
@@ -92,21 +109,25 @@ void SensorLogger::begin(uint8_t soilPin) {
   advertising->setMinPreferred(0x12);
   BLEDevice::startAdvertising();
 
+  // 起動直後にも1回計測して、画面に値を表示できるようにします。
   readAndStore();
   lastMeasure_ = millis();
   lastAdvertise_ = millis();
 }
 
 bool SensorLogger::update() {
+  // loopから繰り返し呼ばれ、通信と定期計測を担当します。
   processBluetooth();
 
   unsigned long now = millis();
   if (!bluetoothConnected_ && now - lastAdvertise_ >= kAdvertiseRetryIntervalMs) {
+    // 接続されていなければ、定期的にBLE広告を出し直します。
     lastAdvertise_ = now;
     BLEDevice::startAdvertising();
   }
 
   if (now - lastMeasure_ >= kMeasureIntervalMs) {
+    // 計測間隔を過ぎたら、新しいログを保存します。
     lastMeasure_ = now;
     readAndStore();
     return true;
@@ -115,6 +136,7 @@ bool SensorLogger::update() {
 }
 
 void SensorLogger::refreshSensors() {
+  // センサーを読み直します。ログには保存せず、画面表示だけを更新します。
   SensorReading reading = {};
   sensors_event_t humidityEvent;
   sensors_event_t temperatureEvent;
@@ -153,11 +175,13 @@ size_t SensorLogger::logCount() const {
 }
 
 bool SensorLogger::formatTimestamp(int64_t timestamp, char* buffer, size_t bufferSize) const {
+  // 秒数を、人が読みやすい「年/月/日 時:分:秒」に変換します。
   if (bufferSize == 0) {
     return false;
   }
 
   if (timeSynchronized_) {
+    // 時刻合わせ済みなら、ESP32の標準時刻変換を使います。
     time_t unixTimestamp = static_cast<time_t>(timestamp);
     struct tm date;
     localtime_r(&unixTimestamp, &date);
@@ -165,6 +189,7 @@ bool SensorLogger::formatTimestamp(int64_t timestamp, char* buffer, size_t buffe
     return true;
   }
 
+  // 時刻合わせ前は、起動してからの経過秒数を仮の日付として表示します。
   int year = static_cast<int>(kInitialYear);
   int month = 1;
   int day = 1;
@@ -193,6 +218,7 @@ bool SensorLogger::getCurrentTime(char* buffer, size_t bufferSize) const {
 }
 
 void SensorLogger::readAndStore() {
+  // センサーを読み取り、最新値とログの両方へ保存します。
   sensors_event_t humidityEvent;
   sensors_event_t temperatureEvent;
   SensorReading reading = {};
@@ -209,6 +235,7 @@ void SensorLogger::readAndStore() {
   reading.timestamp = currentTimestamp();
   latest_ = reading;
 
+  // 配列が満杯になったら、一番古いデータから上書きします。
   size_t writeIndex = (logStart_ + logCount_) % kMaxLogEntries;
   if (logCount_ == kMaxLogEntries) {
     log_[logStart_] = reading;
@@ -220,6 +247,7 @@ void SensorLogger::readAndStore() {
 }
 
 void SensorLogger::processBluetooth() {
+  // 受信した文字を改行ごとの命令に分けて実行します。
   while (commandBuffer_.indexOf('\n') >= 0 || commandBuffer_.indexOf('\r') >= 0) {
     int lineEnd = commandBuffer_.indexOf('\n');
     int carriageReturn = commandBuffer_.indexOf('\r');
@@ -235,6 +263,7 @@ void SensorLogger::processBluetooth() {
 }
 
 void SensorLogger::receiveBluetoothData(const String& data) {
+  // BLEで届いた文字を命令バッファへ追加します。
   for (size_t index = 0; index < data.length(); ++index) {
     char character = data[index];
     if (character == '\n' || character == '\r') {
@@ -246,6 +275,7 @@ void SensorLogger::receiveBluetoothData(const String& data) {
 }
 
 void SensorLogger::applyHistoricalTimeAdjustment(int64_t epoch) {
+  // 時刻合わせ前に保存したログへ、正しい時刻との差を加えます。
   if (historicalAdjustmentApplied_ || timeSynchronized_) {
     return;
   }
@@ -263,13 +293,17 @@ void SensorLogger::applyHistoricalTimeAdjustment(int64_t epoch) {
 }
 
 void SensorLogger::processCommand(const String& command) {
+  // アプリから届いた命令を判定します。
   if (command == "GET_LOG") {
+    // 保存済みのログを順番に送ります。
     sendLog();
   } else if (command == "CLEAR_LOG") {
+    // ログを空にして、完了通知を送ります。
     clearLog();
     txCharacteristic_->setValue("OK_CLEARED\n");
     txCharacteristic_->notify();
   } else if (command.startsWith("TIME:")) {
+    // アプリから受け取った時刻で、時計を合わせます。
     unsigned long epoch = command.substring(5).toInt();
     unsigned int year;
     unsigned int month;
@@ -302,6 +336,7 @@ void SensorLogger::processCommand(const String& command) {
 }
 
 void SensorLogger::sendLog() {
+  // 保存したログを1行ずつ作り、BLE通知で送ります。
   for (size_t index = 0; index < logCount_; ++index) {
     size_t logIndex = (logStart_ + index) % kMaxLogEntries;
     const SensorReading& reading = log_[logIndex];
@@ -325,6 +360,7 @@ void SensorLogger::sendLog() {
 }
 
 void SensorLogger::sendNotification(const char* data) {
+  // BLE通知には一度に送れる長さの制限があるため、短く分割します。
   constexpr size_t kNotificationSize = 20;
   uint8_t notification[kNotificationSize];
   size_t length = strlen(data);
@@ -338,11 +374,13 @@ void SensorLogger::sendNotification(const char* data) {
 }
 
 void SensorLogger::clearLog() {
+  // 配列の中身を消す代わりに、件数を0にして空として扱います。
   logStart_ = 0;
   logCount_ = 0;
 }
 
 int64_t SensorLogger::currentTimestamp() const {
+  // 現在の経過秒数に時刻の差を足して、現在時刻を返します。
   int64_t elapsedSeconds = millis() / 1000UL;
   return timeSynchronized_ ? epochOffset_ + elapsedSeconds : elapsedSeconds;
 }
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
index 8710819..b37274b 100644
--- a/firmware/SensorLogger.h
+++ b/firmware/SensorLogger.h
@@ -6,32 +6,45 @@ class BLECharacteristic;
 class BLEServer;
 
 struct SensorReading {
-  int64_t timestamp;
-  float temperature;
-  float humidity;
-  float illuminance;
-  uint16_t soilMoisture;
+  int64_t timestamp; // 計測した時刻（秒）
+  float temperature; // 温度（℃）
+  float humidity; // 湿度（%）
+  float illuminance; // 明るさ（lux）
+  uint16_t soilMoisture; // 土壌センサーの値
 };
 
 class SensorLogger {
 public:
   static constexpr size_t kMaxLogEntries = 2000;
 
+  // センサー、BLE、保存データを使い始める準備をします。
   void begin(uint8_t soilPin);
+  // BLEの受信と、一定時間ごとの計測を行います。
   bool update();
+  // センサーを読み取り、画面表示用の最新値を更新します。
   void refreshSensors();
+  // 最後に読み取ったセンサー値を返します。
   const SensorReading& latest() const;
+  // 1件以上のログが保存されているかを返します。
   bool hasReading() const;
+  // 保存されているログの件数を返します。
   size_t logCount() const;
+  // 現在時刻を文字列にしてbufferへ書き込みます。
   bool getCurrentTime(char* buffer, size_t bufferSize) const;
+  // 秒数を年月日と時刻の文字列に変換します。
   bool formatTimestamp(int64_t timestamp, char* buffer, size_t bufferSize) const;
+  // BLEで表示する名前を返します。
   const char* bluetoothName() const;
+  // BLE機器が接続中かを返します。
   bool isBluetoothConnected() const;
 
 private:
+  // センサーを読み取る間隔（現在は1時間）です。
   static constexpr unsigned long kMeasureIntervalMs = 3600000UL;
+  // BLE接続がないとき、広告を再開する間隔です。
   static constexpr unsigned long kAdvertiseRetryIntervalMs = 500UL;
 
+  // 内部処理用の関数です。
   void readAndStore();
   void processBluetooth();
   void processCommand(const String& command);
@@ -42,22 +55,22 @@ private:
   void applyHistoricalTimeAdjustment(int64_t epoch);
   int64_t currentTimestamp() const;
 
-  BLEServer* server_ = nullptr;
-  BLECharacteristic* txCharacteristic_ = nullptr;
-  SensorReading log_[kMaxLogEntries] = {};
-  SensorReading latest_ = {};
-  size_t logStart_ = 0;
-  size_t logCount_ = 0;
-  uint8_t soilPin_ = 0;
-  unsigned long lastMeasure_ = 0;
-  unsigned long lastAdvertise_ = 0;
-  int64_t epochOffset_ = 0;
-  int64_t historicalEpochOffset_ = 0;
-  bool timeSynchronized_ = false;
-  bool historicalAdjustmentApplied_ = false;
-  bool bluetoothConnected_ = false;
-  String bluetoothName_;
-  String commandBuffer_;
+  BLEServer* server_ = nullptr; // BLEサーバー本体
+  BLECharacteristic* txCharacteristic_ = nullptr; // アプリへ通知する通路
+  SensorReading log_[kMaxLogEntries] = {}; // 最大2000件の計測ログ
+  SensorReading latest_ = {}; // 最新の計測値
+  size_t logStart_ = 0; // 一番古いログの位置
+  size_t logCount_ = 0; // 現在のログ件数
+  uint8_t soilPin_ = 0; // 土壌センサーを接続したGPIO番号
+  unsigned long lastMeasure_ = 0; // 最後に計測した時刻
+  unsigned long lastAdvertise_ = 0; // 最後にBLE広告を開始した時刻
+  int64_t epochOffset_ = 0; // 現在時刻を合わせるための差
+  int64_t historicalEpochOffset_ = 0; // 過去ログに加える時刻の差
+  bool timeSynchronized_ = false; // 時刻合わせが済んだか
+  bool historicalAdjustmentApplied_ = false; // 過去ログの補正が済んだか
+  bool bluetoothConnected_ = false; // BLE接続中か
+  String bluetoothName_; // BLEに表示する名前
+  String commandBuffer_; // BLEから受け取った未処理の文字
 
   friend class SensorLoggerCallbacks;
   friend class SensorLoggerServerCallbacks;
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 164f065..d199cdd 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -1,30 +1,34 @@
+// A2DPは、スマートフォンから音楽を受信するBluetoothの仕組みです。
 #include "BluetoothA2DPSink.h"
 #include <Wire.h>
 #include <U8g2lib.h>
 #include "NeoPixelController.h"
 #include "SensorLogger.h"
 
+// スマートフォンのBluetooth一覧に表示されるスピーカー名です。
 const char kA2dpDeviceName[] = "BT_Speaker5.5";
 
-// I2C接続のOLED設定 (SSD1306 128x64)
+// I2Cで接続した128x64ドットのOLED画面です。
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
 
+// このプログラムで使う機能の担当者を作ります。
 BluetoothA2DPSink a2dp_sink;
 NeoPixelController neoPixelController;
 SensorLogger sensorLogger;
 
-// 表示用変数
+// 音楽情報と画面更新に使う変数です。
 String currentTitle = "未接続";
 String currentArtist = "";
-int currentVolumePercent = 0; // 音量 (0 ~ 100%)
+int currentVolumePercent = 0; // 音量（0〜100%）
 bool bluetoothConnected = false;
 bool musicPlaying = false;
 unsigned long lastDisplayUpdate = 0;
 
-// 画面全体を再描画する関数
+// OLEDの内容を現在の状態に合わせて描き直します。
 void updateDisplay() {
   u8g2.clearBuffer();
 
+  // 音楽を再生していないときは、センサーの情報を表示します。
   if (!bluetoothConnected || !musicPlaying) {
     u8g2.setFont(u8g2_font_6x10_tf);
     const SensorReading& reading = sensorLogger.latest();
@@ -61,42 +65,38 @@ void updateDisplay() {
     return;
   }
   
-  // --------------------------------------------------
-  // 1. 音量表示エリア（最上部：英数フォント）
-  // --------------------------------------------------
+  // 音楽を再生中は、音量と曲名を表示します。
+  // 上の部分は小さい英数字フォントで音量を表示します。
   u8g2.setFont(u8g2_font_6x10_tf);
   
-  // "Vol: 80%" のテキスト描画
+  // 例: 「Vol: 80%」という文字を作って表示します。
   char volStr[16];
   snprintf(volStr, sizeof(volStr), "Vol: %3d%%", currentVolumePercent);
   u8g2.drawStr(0, 10, volStr);
 
-  // 音量バーの描画
-  int barWidth = map(currentVolumePercent, 0, 100, 0, 50); // 50ピクセル幅に変換
-  u8g2.drawFrame(75, 2, 52, 9);             // 外枠
-  u8g2.drawBox(76, 3, barWidth, 7);           // バーの中身
+  // 音量の割合を、0〜50ドットの長さに変換して棒グラフにします。
+  int barWidth = map(currentVolumePercent, 0, 100, 0, 50);
+  u8g2.drawFrame(75, 2, 52, 9); // 棒グラフの外枠
+  u8g2.drawBox(76, 3, barWidth, 7); // 音量に応じた中身
 
   u8g2.drawLine(0, 13, 128, 13);            // 区切り線
 
-  // --------------------------------------------------
-  // 2. 曲名・アーティスト表示エリア（日本語フォント）
-  // --------------------------------------------------
-  // 日本語フォントに切り替え (美咲フォント UTF-8)
-  u8g2.setFont(u8g2_font_unifont_t_japanese1); 
+  // 下の部分は、日本語を含む曲名とアーティスト名を表示します。
+  u8g2.setFont(u8g2_font_unifont_t_japanese1);
 
-  // 曲名の表示 (y=32)
+  // 曲名を表示します。drawUTF8は日本語も扱える関数です。
   u8g2.drawUTF8(0, 32, currentTitle.c_str());
 
-  // アーティスト名の表示 (y=54)
+  // アーティスト名が空でないときだけ表示します。
   if (currentArtist.length() > 0) {
-    // アーティスト名も日本語フォントのまま描画します
     u8g2.drawUTF8(0, 54, currentArtist.c_str());
   }
 
-  u8g2.sendBuffer(); // 画面転送
+  // ここまでの描画内容を、実際のOLED画面へ送ります。
+  u8g2.sendBuffer();
 }
 
-// メタデータ（曲名・アーティスト名）の受信コールバック
+// スマートフォンから曲名やアーティスト名を受け取ったときに呼ばれます。
 void avrc_metadata_callback(uint8_t id, const uint8_t *text) {
   bool updated = false;
 
@@ -113,7 +113,7 @@ void avrc_metadata_callback(uint8_t id, const uint8_t *text) {
   }
 }
 
-// 音量変更時のコールバック関数
+// スマートフォン側で音量が変わったときに呼ばれます。
 void volume_changed_callback(int volume) {
   currentVolumePercent = map(volume, 0, 127, 0, 100);
   if (bluetoothConnected && musicPlaying) {
@@ -122,12 +122,14 @@ void volume_changed_callback(int volume) {
 }
 
 void audio_state_changed_callback(esp_a2d_audio_state_t state, void *) {
+  // 音声が流れ始めたかどうかを保存し、LEDと画面を更新します。
   musicPlaying = state == ESP_A2D_AUDIO_STATE_STARTED;
   neoPixelController.setPlaying(musicPlaying);
   updateDisplay();
 }
 
 void connection_state_changed_callback(esp_a2d_connection_state_t state, void *) {
+  // スマートフォンとの接続状態を保存します。
   bluetoothConnected = state == ESP_A2D_CONNECTION_STATE_CONNECTED;
   if (!bluetoothConnected) {
     musicPlaying = false;
@@ -136,15 +138,15 @@ void connection_state_changed_callback(esp_a2d_connection_state_t state, void *)
 }
 
 void setup() {
+  // setupは、電源を入れた直後に1回だけ実行されます。
   Serial.begin(115200);
 
   neoPixelController.begin(18);
 
-  // SDAをGPIO 19、SCLをGPIO 32 に設定
-  // （配線に合わせて Wire.begin(SDA_PIN, SCL_PIN) の順で指定します）
+  // I2Cの配線を設定します。Wire.begin(SDA, SCL)の順です。
   Wire.begin(21, 22);
   
-  // OLED初期化
+  // OLEDを使える状態にします。
   u8g2.begin();
   u8g2.enableUTF8Print(); // UTF-8（日本語）描画を有効化
 
@@ -152,7 +154,8 @@ void setup() {
   updateDisplay();
   lastDisplayUpdate = millis();
 
-  // I2S ピン設定 (BCK: 27, WS: 25, DOUT: 26)
+  // I2Sは、Bluetooth音声をアンプへ送るための通信方式です。
+  // BCK=27、WS=25、音声データ出力=DOUT=26に配線しています。
   i2s_pin_config_t my_pin_config = {
     .bck_io_num = 27,
     .ws_io_num = 25,
@@ -162,17 +165,18 @@ void setup() {
 
   a2dp_sink.set_pin_config(my_pin_config);
 
-  // コールバック登録
+  // Bluetoothでイベントが起きたときの通知先を登録します。
   a2dp_sink.set_avrc_metadata_callback(avrc_metadata_callback);
   a2dp_sink.set_on_volumechange(volume_changed_callback);
   a2dp_sink.set_on_audio_state_changed(audio_state_changed_callback);
   a2dp_sink.set_on_connection_state_changed(connection_state_changed_callback);
 
-  // Bluetooth起動
+  // Bluetoothスピーカーとして起動します。
   a2dp_sink.start(kA2dpDeviceName);
 }
 
 void loop() {
+  // loopは何度も繰り返し実行されます。
   neoPixelController.update();
   bool newReading = sensorLogger.update();
   unsigned long now = millis();

From 2b3b7cfc4e2535aebf43f6a9e0bc096c9db8ff17 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 20:59:30 +0900
Subject: [PATCH 16/18] =?UTF-8?q?=E3=83=95=E3=82=A9=E3=83=B3=E3=83=88?=
 =?UTF-8?q?=E3=81=AB=E3=81=AA=E3=81=84=E6=96=87=E5=AD=97=E3=81=AF=E3=80=81?=
 =?UTF-8?q?=E3=83=88=E3=83=BC=E3=83=95=E3=81=B8=E7=BD=AE=E3=81=8D=E6=8F=9B?=
 =?UTF-8?q?=E3=81=88?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/firmware.ino | 67 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 3 deletions(-)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index d199cdd..997b225 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -24,6 +24,65 @@ bool bluetoothConnected = false;
 bool musicPlaying = false;
 unsigned long lastDisplayUpdate = 0;
 
+// UTF-8の文字列を1文字ずつ調べ、フォントにない文字を□へ置き換えます。
+// U8g2は、知らない文字を自動では表示せず、次の文字へ進んでしまいます。
+String replaceMissingGlyphs(const String& text) {
+  String result;
+
+  for (size_t index = 0; index < text.length();) {
+    const uint8_t firstByte = static_cast<uint8_t>(text[index]);
+    uint32_t codePoint = 0;
+    size_t byteCount = 0;
+
+    // UTF-8の先頭バイトから、1文字のバイト数を判定します。
+    if (firstByte < 0x80) {
+      codePoint = firstByte;
+      byteCount = 1;
+    } else if ((firstByte & 0xE0) == 0xC0 && index + 1 < text.length()) {
+      codePoint = firstByte & 0x1F;
+      byteCount = 2;
+    } else if ((firstByte & 0xF0) == 0xE0 && index + 2 < text.length()) {
+      codePoint = firstByte & 0x0F;
+      byteCount = 3;
+    } else if ((firstByte & 0xF8) == 0xF0 && index + 3 < text.length()) {
+      codePoint = firstByte & 0x07;
+      byteCount = 4;
+    } else {
+      // 壊れたUTF-8も、表示できない文字としてトーフにします。
+      result += "□";
+      ++index;
+      continue;
+    }
+
+    // 2バイト目以降をつなげて、Unicodeの文字コードを作ります。
+    bool valid = true;
+    for (size_t offset = 1; offset < byteCount; ++offset) {
+      const uint8_t nextByte = static_cast<uint8_t>(text[index + offset]);
+      if ((nextByte & 0xC0) != 0x80) {
+        valid = false;
+        break;
+      }
+      codePoint = (codePoint << 6) | (nextByte & 0x3F);
+    }
+
+    if (!valid) {
+      result += "□";
+      ++index;
+      continue;
+    }
+
+    // 幅が0なら、その文字の絵がフォントにないと判断します。
+    if (u8g2.getGlyphWidth(codePoint) == 0) {
+      result += "□";
+    } else {
+      result += text.substring(index, index + byteCount);
+    }
+    index += byteCount;
+  }
+
+  return result;
+}
+
 // OLEDの内容を現在の状態に合わせて描き直します。
 void updateDisplay() {
   u8g2.clearBuffer();
@@ -84,12 +143,14 @@ void updateDisplay() {
   // 下の部分は、日本語を含む曲名とアーティスト名を表示します。
   u8g2.setFont(u8g2_font_unifont_t_japanese1);
 
-  // 曲名を表示します。drawUTF8は日本語も扱える関数です。
-  u8g2.drawUTF8(0, 32, currentTitle.c_str());
+  // フォントにない文字は□に置き換えてから表示します。
+  String displayTitle = replaceMissingGlyphs(currentTitle);
+  u8g2.drawUTF8(0, 32, displayTitle.c_str());
 
   // アーティスト名が空でないときだけ表示します。
   if (currentArtist.length() > 0) {
-    u8g2.drawUTF8(0, 54, currentArtist.c_str());
+    String displayArtist = replaceMissingGlyphs(currentArtist);
+    u8g2.drawUTF8(0, 54, displayArtist.c_str());
   }
 
   // ここまでの描画内容を、実際のOLED画面へ送ります。

From ca05ef14e5efda32cef4bd70d7f1fd3846965607 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 21:02:22 +0900
Subject: [PATCH 17/18] =?UTF-8?q?getUTF8Width=20=E3=81=AB=E5=A4=89?=
 =?UTF-8?q?=E6=9B=B4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/firmware.ino | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 997b225..bbda449 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -31,21 +31,16 @@ String replaceMissingGlyphs(const String& text) {
 
   for (size_t index = 0; index < text.length();) {
     const uint8_t firstByte = static_cast<uint8_t>(text[index]);
-    uint32_t codePoint = 0;
     size_t byteCount = 0;
 
     // UTF-8の先頭バイトから、1文字のバイト数を判定します。
     if (firstByte < 0x80) {
-      codePoint = firstByte;
       byteCount = 1;
     } else if ((firstByte & 0xE0) == 0xC0 && index + 1 < text.length()) {
-      codePoint = firstByte & 0x1F;
       byteCount = 2;
     } else if ((firstByte & 0xF0) == 0xE0 && index + 2 < text.length()) {
-      codePoint = firstByte & 0x0F;
       byteCount = 3;
     } else if ((firstByte & 0xF8) == 0xF0 && index + 3 < text.length()) {
-      codePoint = firstByte & 0x07;
       byteCount = 4;
     } else {
       // 壊れたUTF-8も、表示できない文字としてトーフにします。
@@ -54,7 +49,7 @@ String replaceMissingGlyphs(const String& text) {
       continue;
     }
 
-    // 2バイト目以降をつなげて、Unicodeの文字コードを作ります。
+    // 2バイト目以降がUTF-8の続きになっているか確認します。
     bool valid = true;
     for (size_t offset = 1; offset < byteCount; ++offset) {
       const uint8_t nextByte = static_cast<uint8_t>(text[index + offset]);
@@ -62,7 +57,6 @@ String replaceMissingGlyphs(const String& text) {
         valid = false;
         break;
       }
-      codePoint = (codePoint << 6) | (nextByte & 0x3F);
     }
 
     if (!valid) {
@@ -71,11 +65,15 @@ String replaceMissingGlyphs(const String& text) {
       continue;
     }
 
+    // 1文字分のUTF-8文字列を作ります。
+    String character = text.substring(index, index + byteCount);
+
     // 幅が0なら、その文字の絵がフォントにないと判断します。
-    if (u8g2.getGlyphWidth(codePoint) == 0) {
+    // getGlyphWidthは使えるU8g2の版が限られるため、getUTF8Widthを使います。
+    if (u8g2.getUTF8Width(character.c_str()) == 0) {
       result += "□";
     } else {
-      result += text.substring(index, index + byteCount);
+      result += character;
     }
     index += byteCount;
   }

From c15850a074248d646b6809a4b9db2f2701b14082 Mon Sep 17 00:00:00 2001
From: Koichi Ito <koichii@live.jp>
Date: Sun, 20 Sep 2026 21:27:34 +0900
Subject: [PATCH 18/18] =?UTF-8?q?=E3=83=88=E3=83=BC=E3=83=95=E5=AE=8C?=
 =?UTF-8?q?=E6=88=90?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 firmware/firmware.ino | 54 +++++++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 23 deletions(-)

diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index bbda449..5b0ba36 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -24,32 +24,40 @@ bool bluetoothConnected = false;
 bool musicPlaying = false;
 unsigned long lastDisplayUpdate = 0;
 
-// UTF-8の文字列を1文字ずつ調べ、フォントにない文字を□へ置き換えます。
-// U8g2は、知らない文字を自動では表示せず、次の文字へ進んでしまいます。
-String replaceMissingGlyphs(const String& text) {
-  String result;
+// UTF-8の文字列を1文字ずつ描画します。
+// フォントにない文字は、フォントに頼らず四角形を直接描きます。
+void drawUtf8WithTofu(uint8_t x, uint8_t y, const String& text) {
+  constexpr uint8_t kTofuSize = 12;
+  constexpr uint8_t kTofuAdvance = 16;
+  uint8_t cursorX = x;
 
   for (size_t index = 0; index < text.length();) {
     const uint8_t firstByte = static_cast<uint8_t>(text[index]);
     size_t byteCount = 0;
+    uint32_t codePoint = 0;
 
     // UTF-8の先頭バイトから、1文字のバイト数を判定します。
     if (firstByte < 0x80) {
+      codePoint = firstByte;
       byteCount = 1;
     } else if ((firstByte & 0xE0) == 0xC0 && index + 1 < text.length()) {
+      codePoint = firstByte & 0x1F;
       byteCount = 2;
     } else if ((firstByte & 0xF0) == 0xE0 && index + 2 < text.length()) {
+      codePoint = firstByte & 0x0F;
       byteCount = 3;
     } else if ((firstByte & 0xF8) == 0xF0 && index + 3 < text.length()) {
+      codePoint = firstByte & 0x07;
       byteCount = 4;
     } else {
-      // 壊れたUTF-8も、表示できない文字としてトーフにします。
-      result += "□";
+      // 壊れたUTF-8も、表示できない文字としてトーフを描きます。
+      u8g2.drawFrame(cursorX, y - kTofuSize, kTofuSize, kTofuSize);
+      cursorX += kTofuAdvance;
       ++index;
       continue;
     }
 
-    // 2バイト目以降がUTF-8の続きになっているか確認します。
+    // 2バイト目以降をつなげて、Unicodeの文字コードを作ります。
     bool valid = true;
     for (size_t offset = 1; offset < byteCount; ++offset) {
       const uint8_t nextByte = static_cast<uint8_t>(text[index + offset]);
@@ -57,28 +65,30 @@ String replaceMissingGlyphs(const String& text) {
         valid = false;
         break;
       }
+      codePoint = (codePoint << 6) | (nextByte & 0x3F);
     }
 
     if (!valid) {
-      result += "□";
+      u8g2.drawFrame(cursorX, y - kTofuSize, kTofuSize, kTofuSize);
+      cursorX += kTofuAdvance;
       ++index;
       continue;
     }
 
-    // 1文字分のUTF-8文字列を作ります。
-    String character = text.substring(index, index + byteCount);
-
-    // 幅が0なら、その文字の絵がフォントにないと判断します。
-    // getGlyphWidthは使えるU8g2の版が限られるため、getUTF8Widthを使います。
-    if (u8g2.getUTF8Width(character.c_str()) == 0) {
-      result += "□";
+    // フォントに文字があれば、実際のグリフを描画します。
+    // 16ビットを超える文字は、このフォントでは表示できないためトーフにします。
+    if (codePoint <= 0xFFFF && u8g2_IsGlyph(u8g2.getU8g2(), codePoint)) {
+      u8g2.drawGlyph(cursorX, y, static_cast<uint16_t>(codePoint));
+      cursorX += static_cast<uint8_t>(u8g2_GetGlyphWidth(
+        u8g2.getU8g2(), static_cast<uint16_t>(codePoint)));
     } else {
-      result += character;
+      // □の字形がフォントにない場合でも、四角形なら必ず表示できます。
+      u8g2.drawFrame(cursorX, y - kTofuSize, kTofuSize, kTofuSize);
+      cursorX += kTofuAdvance;
     }
+
     index += byteCount;
   }
-
-  return result;
 }
 
 // OLEDの内容を現在の状態に合わせて描き直します。
@@ -141,14 +151,12 @@ void updateDisplay() {
   // 下の部分は、日本語を含む曲名とアーティスト名を表示します。
   u8g2.setFont(u8g2_font_unifont_t_japanese1);
 
-  // フォントにない文字は□に置き換えてから表示します。
-  String displayTitle = replaceMissingGlyphs(currentTitle);
-  u8g2.drawUTF8(0, 32, displayTitle.c_str());
+  // フォントにない文字は、四角形のトーフとして表示します。
+  drawUtf8WithTofu(0, 32, currentTitle);
 
   // アーティスト名が空でないときだけ表示します。
   if (currentArtist.length() > 0) {
-    String displayArtist = replaceMissingGlyphs(currentArtist);
-    u8g2.drawUTF8(0, 54, displayArtist.c_str());
+    drawUtf8WithTofu(0, 54, currentArtist);
   }
 
   // ここまでの描画内容を、実際のOLED画面へ送ります。