Can't access to Service Data in the GATT

[JpEncausse]

Operating System

Windows 11

IDE version

PlatformIO

Board

seeed-xiao-afruitnrf52-nrf52840-sense

BSP version

adafruit/Adafruit BluefruitLE nRF51@^1.10.0

Sketch

This code was suggested by ChatGPT in loop ...

Option 1

BLEClientService pixelService("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
BLEClientCharacteristic pixelCharacteristic("6e400003-b5a3-f393-e0a9-e50e24dcca9e");

void PixelDiceManager::connectCallback(uint16_t conn_handle) {
  BLEConnection* connection = Bluefruit.Connection(conn_handle);
  char central_name[32] = { 0 };
  connection->getPeerName(central_name, sizeof(central_name));
  Serial.print("Connecté à ");
  Serial.println(central_name);

  delay(100);
  if (pixelService.discover(conn_handle)) {
    if (pixelCharacteristic.discover()) {
      pixelCharacteristic.setNotifyCallback(notif_callback_wrapper);
      pixelCharacteristic.enableNotify();
      Serial.println("Abonné aux notifications du dé Pixel.");
    } else {
      Serial.println("Caractéristique non trouvée.");
      Bluefruit.disconnect(conn_handle);
    }
  } else {
    Serial.println("Service non trouvé.");
    Bluefruit.disconnect(conn_handle);
  }
}

Option 2

BLEClientUart clientUart;
void bleuart_rx_callback(BLEClientUart& uart_svc) {
  Serial.print("Données reçues : ");
  while (uart_svc.available()) {
    Serial.print((char)uart_svc.read());
  }
  Serial.println();
}

void PixelDiceManager::connectCallback(uint16_t conn_handle) {
  Serial.println("Connecté");

  if (clientUart.discover(conn_handle)) {
    Serial.println("Service BLE UART trouvé");
    clientUart.enableTXD();
    clientUart.setRxCallback(bleuart_rx_callback);
    clientUart.enableTXD();
    Serial.println("Prêt à recevoir des données");
  } else {
    Serial.println("Service BLE UART non trouvé");
    Bluefruit.disconnect(conn_handle);
  }
}

What happened ?

I try to read data from a BLE device using Bluefruit

• I correctly have access to Advertiser Data
• I can connect to the device
• I can't discover the Service Data
• It works with ESP-32 BLE library

The protocol is described here

According to ChatGPT

• the Service Data can't be find and should require GATT level access or something similar
• the nRF lib see the service and ESP-32 BLE library also works
• the weird things? is that ServiceUUID is same as notifUUID 6e400001-b5a3-f393-e0a9-e50e24dcca9e

I don't know how to do to perform list services or go deeper to get that service or notification to validate if it's a bug, a limitation of the library or if a workaround is possible ?

How to reproduce ?

It requires the PixelDice to test

Debug Log

No response

Screenshots

Here is the nRF screenshot

[JpEncausse]

It seems it's not possible de read characteristics correctly and even force CCCD.

The device expose content :

There is no workaround to force 0x2902 and Notification is broken (it works with ESP-32 lib)

BLEClientService        pixelService("6e400001-b5a3-f393-e0a9-e50e24dcca9e"); 
BLEClientCharacteristic pixelNotify ("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
BLEClientCharacteristic pixelWrite  ("6e400002-b5a3-f393-e0a9-e50e24dcca9e");

// All has been tested initialized (or not) in setup()

void dumpCharacteristic(BLEClientCharacteristic characteristic) {
  uint8_t props = characteristic.properties();
  if (props & CHR_PROPS_NOTIFY)   Serial.println("  🔔 NOTIFY");
  if (props & CHR_PROPS_READ)     Serial.println("  📖 READ");
  if (props & CHR_PROPS_WRITE)    Serial.println("  ✍️ WRITE");
  Serial.println();
}

Serial.println("Discovering services ... "); // "6e400001-b5a3-f393-e0a9-e50e24dcca9e"
Serial.println(Bluefruit.Discovery._discoverService(conn_handle, pixelService));
// => 0

Serial.println("Discovering charact Notify ... "); // "6e400001-b5a3-f393-e0a9-e50e24dcca9e"
Serial.println(Bluefruit.Discovery.discoverCharacteristic(conn_handle, pixelNotify));
// => 1
dumpCharacteristic(pixelNotify);
// => ✍️ WRITE
pixelNotify.setNotifyCallback(notif_callback_wrapper, true);
Serial.println(pixelNotify.enableNotify());
// =>  0

Serial.println("Discovering charact Write ... "); // "6e400002-b5a3-f393-e0a9-e50e24dcca9e"
Serial.println(Bluefruit.Discovery.discoverCharacteristic(conn_handle, pixelWrite));
// =>  0