Calling ad2dp_sink.start with identifier taken from a String

[edholness-starkstrom]

Hi,

I have a basic implementation working but I would like to be able to take the name for the Bluetooth device from the chipID for the ESP32 controller so that the device can have a unique name, as I'm intending to have multiple setups and want to use something unique to the device. I can find the chipID easily using some code lifted from the ESP32 examples in the Arduino IDE:

uint32_t chipId = 0;
void setup() {
  for (int i = 0; i < 17; i = i + 8) {
    chipId |= ((ESP.getEfuseMac() >> (40 - i)) & 0xff) << i;
  }

What I can't then get to work is to be able to run a2dp_sink.start(chipId). This fails to compile, I initially thought this was because it is an integer. I have then tried using the following to convert the chipID to a string, before starting the A2DP sink but this also fails to compile with "no matching function for call to 'BluetoothA2DPSink::start(String&)'":

chipString=String(chipId);

a2dp_sink.start(chipString);

I have also tried concatenating other things together but it appears you can't set a string to be used as the A2DP sink name. Apologies if I have missed something here.

[pschatzmann]

you would use the c_str() method of String!

[edholness-starkstrom]

Thanks. Was able to get this to work with a string of text added in front of the chip ID:

  for (int i = 0; i < 17; i = i + 8) {
    chipId |= ((ESP.getEfuseMac() >> (40 - i)) & 0xff) << i;
  }

chipString = "ESP32-" + String(chipId);

const char* chipString2 =chipString.c_str();
 
  a2dp_sink.start(chipString2);