BLE Services and characteristics are not created with configured UUIDs

[dejavu1987]

I am using ESP32-S3 board Lilygo T-Display.

So I have been trying with few different ways of defining services and characteristics using this long string as well as with BLEUUID() function as follows

#define SERVICE_UUID       BLEUUID((uint16_t)0x180D) 
#define CHARACTERISTIC_UUID BLEUUID((uint16_t)0x2A37)
BLEDescriptor heartRateDescriptor(BLEUUID((uint16_t)0x2901));

Following is the sketch where I am trying to create a UART service as specified in Nordic Semiconductor Infocenter

#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>

#define SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E"
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"

BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
uint8_t txValue = 0;
bool deviceConnected = false;

class MyServerCallbacks : public BLEServerCallbacks {
  void onConnect(BLEServer *pServer) {
    deviceConnected = true;
  };

  void onDisconnect(BLEServer *pServer) {
    deviceConnected = false;
  }
};


class MyCallbacks : public BLECharacteristicCallbacks {
  void onWrite(BLECharacteristic *pCharacteristic) {
    std::string rxValue = pCharacteristic->getValue();
  }
};


void
setup() {
  BLEDevice::init("UART Service");
  BLEServer *pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  BLEService *pService = pServer->createService(SERVICE_UUID);

  pCharacteristic = pService->createCharacteristic(
    CHARACTERISTIC_UUID_TX,
    BLECharacteristic::PROPERTY_NOTIFY);

  pCharacteristic->addDescriptor(new BLE2902());

  BLECharacteristic *pCharacteristic = pService->createCharacteristic(
    CHARACTERISTIC_UUID_RX,
    BLECharacteristic::PROPERTY_WRITE);

  pCharacteristic->setCallbacks(new MyCallbacks());

  pService->start();

  pServer->getAdvertising()->start();
}

void loop() {
  // put your main code here, to run repeatedly:
  if (deviceConnected) {
    Serial.printf("*** Sent Value: %d ***\n",
                  txValue);
    pCharacteristic->setValue(&txValue, 1);
    pCharacteristic->notify();
    txValue++;
    delay(1000);
  }
}

The resulting service and characteristics show completely different UUIDs on the NRFConnect app. It also has a wrong PROPERTIES, shows all of them, and instead of 2 there is only one characteristic.

Which is why the logger app does not detect it as a UART enabled device.

What am I doing wrong here?

[cattledog]

@dejavu1987

What am I doing wrong here?

I can not confirm your issue. I see this screen in nrf connect and see the TX characteristic being updated. I have seen instances where older connections are not cleared but don't understand when/why.
Perhaps try using Light Blue which I find easier to use than nrfConnect.

[dejavu1987]

Hey @cattledog ,

Thanks for verifying that for me. It is really strange, I ll give Light Blue a try. Thanks

regards
Anil