reading binary data from bluetooth classic

[learncodingforweb]

Mobile Device Environment
Provide a list of operating systems on which this issue is relevant.

• Device: Android 10
• OS: API 29

Application Environment
Provide information about your development environment:

• React Native version: 0.78.0
• RN Bluetooth Classic version: 1.73.0-rc.13

Describe the bug
I have Connected HC-06 device with computer using USB to TTL converter. If i send string data to android device, then i am able to see it correctly on android phone. But if i try to send binary data e.g. [178, 13, 10] on bluetooth device. then on android phone i am not able to see it correctly.

useEffect(() => {
    let sub: BluetoothEventSubscription | undefined;
    if (connectionStatus === 'connect') {
      sub = device?.onDataReceived((event) => {
        const data = event.data;
        const uint8Array = new Uint8Array(
           [...data].map((char) => char.charCodeAt(0)),
         );
        console.log('reieved data', uint8Array, 'len', uint8Array.length);
      });
    }
    return () => {
      sub?.remove();
    };
  }, [device, connectionStatus]);

[00:02:53] I | ReactNativeJS ▶︎ 'reieved data', { '0': 115, '1': 103, '2': 61, '3': 61, '4': 10 }, 'len', 5

[00:02:53] I | ReactNativeJS ▶︎ 'reieved data', { '0': 68, '1': 81, '2': 111, '3': 61, '4': 10 }, 'len', 5

Note I am connecting to bluetooth device using
device.connect()

Expected behavior
Should be able to get data [178, 13, 10], In other words, how to enable binary data reading?

[kenjdavidson]

So, the first thing I would do is go look at the documentation to see if connecting to the device using the binary connection works better. Right now you're using:

device.connect()

which is using the default rfcomm/delimited connection. This connection is primarily for strings, so unless you're doing the internal magic of converting the binary data to the string representation and then sending it, and then decompiling it (for lack of a better term) to get it back to binary, you're going to run into issues.

You should be able to use

device.connect({type: 'binary'});

It think, or something along those lines. This will connect using binary write/read specific logic and may work better for you. If this still doesn't work, then you'll need to look at:

• Creating your own connection type
• Doing the above, where you convert the binary data to a string so that it is sent properly
• Something else I can't think of at this time.

[learncodingforweb]

I observed that, data from 0 to 127 received correctly, after that data from 128 to 255 is not received correctly.

device.connect({type: 'binary'})

getting error Object literal may only specify known properties, and 'type' does not exist in type 'StandardOptions'.ts(2353)
(property) type: string
Note where device: BluetoothDevice

"react-native-bluetooth-classic": "^1.73.0-rc.13",

[learncodingforweb]

resolved issue by using device.connect({ connectionType: 'binary' }) and data is received in base64 format

[learncodingforweb]

I am not able to transmit binary data to device.write(1). getting error Argument of type 'number' is not assignable to parameter of type 'string | Buffer'.

Even i tried
const uint8Array = new Uint8Array([0, 1])
device.write(uint8Array)
Argument of type 'Uint8Array' is not assignable to parameter of type 'string | Buffer'.
Type 'Uint8Array' is missing the following properties from type 'Buffer': write, toJSON, equals, compare, and 66 more.ts(2345)

is there way i can directly send binary data without using base64 format, i mean buffer directly?

[kenjdavidson]

No, not the way it's currently working, it would break the contract. If you feel like you can improve upon it, feel free to open a PR with comments and examples and we can get that in.