Fix BLE upload: write-with-response on CMD+DATA, on-demand advertising, wake-play-random, remove startup blink

baby_mobile_v2/baby_mobile_v2.ino

@@ -49,6 +49,11 @@
 #include <Adafruit_TinyUSB.h>
 #include <bluefruit.h>
 
+// ============================================================
+// When defined, a wake from deep sleep (button press) plays a random track
+// immediately instead of waiting for user input.
+//#define WAKE_PLAY_RANDOM
+
 // ============================================================
 // POC MODE: stream audio from internal LittleFS instead of SPI flash.
 // Upload tracks via upload_track.py (serial) or BLE (CMD 0x02).
@@ -247,6 +252,10 @@ unsigned long g_lastActivity = 0;
 // USB connected flag
 volatile bool g_usbConnected = false;
 
+// Wake-from-sleep detection. Read before SoftDevice starts (setupBLE), stored here.
+static bool  g_wakeFromSleep = false;
+static uint8_t g_wakeTrack   = 0;
+
 #ifdef POC_INTERNAL_FLASH
 static void pocFilename(uint8_t n, char *buf) {  // buf must be >=16 bytes
     snprintf(buf, 16, "/track%d.wav", n);
@@ -746,8 +755,10 @@ void audioCmd_write_cb(uint16_t conn_handle, BLECharacteristic* chr,
             loadTrackTable();
             Serial.println("BLE: Upload complete");
 #else
-            // Signal loop() to finalize after ring buffer drains.
-            // Don't call loadTrackTable() here — we're in a BLE callback.
+            // Signal loop() to finalize once the ring buffer drains.
+            // Because the DATA characteristic uses write-with-response, every data
+            // packet has been ATT-acknowledged before the client sends this command,
+            // so all bytes are already in the ring buffer by the time we get here.
             if (g_bleUploading) {
                 g_bleFinalizing = true;
                 Serial.println("BLE: Finalizing upload...");
@@ -1003,17 +1014,20 @@ void setupBLE() {
     // Audio service
     audioSvc.begin();
 
-    // Command characteristic (write without response — avoids "GATT already in progress" errors)
-    audioCmd.setProperties(CHR_PROPS_WRITE_WO_RESP);
+    // Command characteristic: write-with-response so JS can await full OS-level
+    // completion before issuing the next operation on any characteristic.
+    audioCmd.setProperties(CHR_PROPS_WRITE);
     audioCmd.setPermission(SECMODE_OPEN, SECMODE_OPEN);
     audioCmd.setMaxLen(240);
     audioCmd.setWriteCallback(audioCmd_write_cb);
     audioCmd.begin();
 
-    // Data characteristic (write without response for speed)
-    audioData.setProperties(CHR_PROPS_WRITE_WO_RESP);
+    // Data characteristic (write with response — ATT flow control ensures the
+    // SoftDevice has acknowledged every packet before the client sends the next,
+    // so CMD_UPLOAD_END can never race ahead of the data stream)
+    audioData.setProperties(CHR_PROPS_WRITE);
     audioData.setPermission(SECMODE_OPEN, SECMODE_OPEN);
-    audioData.setMaxLen(240);
+    audioData.setMaxLen(244);  // must match DATA_CHUNK in ble.js (MTU 247 - 3 = 244)
     audioData.setWriteCallback(audioData_write_cb);
     audioData.begin();
 
@@ -1324,6 +1338,17 @@ void waitButtonRelease(uint8_t btn) {
 // SLEEP / WAKE
 // ============================================================
 
+// One byte from the nRF52840 hardware true random number generator.
+static uint8_t hwRandom() {
+    NRF_RNG->CONFIG = RNG_CONFIG_DERCEN_Enabled << RNG_CONFIG_DERCEN_Pos;  // bias correction on
+    NRF_RNG->EVENTS_VALRDY = 0;
+    NRF_RNG->TASKS_START = 1;
+    while (!NRF_RNG->EVENTS_VALRDY) {}
+    uint8_t v = (uint8_t)NRF_RNG->VALUE;
+    NRF_RNG->TASKS_STOP = 1;
+    return v;
+}
+
 void enterDeepSleep() {
     // Don't sleep if any button is currently LOW — would wake instantly.
     // Also catches floating pins that the internal pull-up isn't winning against.
@@ -1372,22 +1397,6 @@ void setup() {
     digitalWrite(PIN_LED, HIGH);
 
     Serial.begin(115200);
-    Serial.println("...");
-    
-    int c=0;
-    while(c<10) {
-      // pinMode(c, OUTPUT);
-      delay(250);
-      digitalWrite(PIN_LED, HIGH);
-      // digitalWrite(c, HIGH);
-      // Serial.println("0");
-      delay(250);
-      digitalWrite(PIN_LED, LOW);
-      // digitalWrite(c, LOW);
-      // Serial.println(c);
-      c++;
-    }
-
     Serial.println("=== Baby Mobile v2 ===");
     Serial.println("nRF52840 + IS25LP128F + PAM8302A");
 
@@ -1444,11 +1453,31 @@ void setup() {
     usb_msc.begin();
 #endif
 
+    // Read RESETREAS and collect a random byte BEFORE starting the SoftDevice.
+    // Once Bluefruit.begin() enables S140, the SoftDevice owns NRF_RNG and
+    // NRF_POWER — direct register access after that point causes a hard fault.
+    g_wakeFromSleep = (NRF_POWER->RESETREAS & POWER_RESETREAS_OFF_Msk) != 0;
+    NRF_POWER->RESETREAS = 0xFFFFFFFFUL;  // write-1-to-clear
+    if (g_wakeFromSleep) Serial.println("Woke from deep sleep.");
+#ifdef WAKE_PLAY_RANDOM
+    if (g_wakeFromSleep && g_numTracks > 0) {
+        // hwRandom() is safe here — SoftDevice not yet started.
+        g_wakeTrack = hwRandom() % g_numTracks;
+    }
+#endif
+
     // BLE
     setupBLE();
 
     g_lastActivity = millis();
 
+#ifdef WAKE_PLAY_RANDOM
+    if (g_wakeFromSleep && g_numTracks > 0) {
+        Serial.print("Auto-play random track "); Serial.println(g_wakeTrack);
+        audioStart(g_wakeTrack);
+    }
+#endif
+
     digitalWrite(PIN_LED, HIGH);
     Serial.println("Ready! Plug in USB to upload audio, or press a button.");
 }