BLE Connect timeout?

Question

I'm using BLE to connect to a sensor, but if the sensors battery has died it takes ages(30 seconds) for it to timeout. Is there some way to specify a timeout?

BLEClient* client = BLEDevice::createClient();
bool connected = client->connect(bleAddress);

Answer 1

I cannot wrap my head around the fact that this API is actually blocking and fixing this requires changes to FreeRTOS code.

Short answer: no, not possible to set a timeout without making ugly changes.

But the code would be a good approximation if the timeout value is meaningful. Short timeouts (less than 10 secs) will likely require a semaphore.

bool doConnect(uint8_t timeout_secs) {
  static bool connected = false;
  TaskHandle_t hTask;
  xTaskCreate(
      [](void *unused)
      {
        pClient->connect(&device);
        connected = true;
        vTaskDelete(nullptr); // important line, FreeRTOS will crash.
      },
      "connect", //name of the task for debugging purposes.
      8192, // stack size
      nullptr, // object passed as void* unused
      2,  // priority
      &hTask);

  uint64_t expiration = millis() + timeout_secs * 1000;
  while  (!connected && millis() < expiration) {
    delay(500); // give the connect task a chance to run.
  }
  vTaskDelete(hTask);
  return connected;
}