How to read Generic Access service/characteristics using react-native-ble-manager

Question

I have a client app on Android 10 built with react native

Android SDK:
  API Levels: 23, 28
  Build Tools: 28.0.3
react: ^16.9.0 => 16.9.0
react-native: ^0.62.2 => 0.62.2

What works: service discovery connecting reading/writing/notify of custom (128 bit) characteritics

What does not work: reading the characteristics of general access service 0x1800

Service discovery: BleManager.retrieveServices /snip/ "characteristics": [{"characteristic": "2a00", "properties": [Object], "service": "1800"}, This is the full device name characteristic.

I can read it using any BLE client app, e.g. LightBlue, so the server side works.

I have tried reading 16-bit short UUID:

    BleManager.read(peripheral.id, 
      '1800', 
      '2a00').then((readData) => {
      console.log(readData);          
    }).catch((error) => {
      console.log(error); 
    });

and also full 128b version:

BleManager.read(peripheral.id, 
  '00001800-0000-1000-8000-00805f9b34fb', 
  '00002a00-0000-1000-8000-00805f9b34fb').then((readData) => {
  console.log(readData);          
}).catch((error) => {
  console.log(error); 
});

In both cases catch error "00002a00-0000-1000-8000-00805f9b34fb not found".

Note that the same code works fine for my own custom UUIDs. peripheral.id is MAC address of my server peripheral.

Any ideas what can be wrong? Thanks!

Knut Knut · Accepted Answer · 2020-09-18T09:37:39

I found the problem. It was a race condition where retrieve services was not complete before reading characteristics. Solution:

BleManager.retrieveServices(peripheral.id).then((peripheralInfo) => {
    BleManager.read(peripheral.id, 
      '1800', 
      '2a00').then((readData) => {
      console.log(readData);          
    }).catch((error) => {
      console.log(error); 
    });
})

How to read Generic Access service/characteristics using react-native-ble-manager

1 Answers