Wsrtjtyk

I'm trying to send a sample hex string to a BLE device via web bluetooth.

This string is sending perfectly fine on OSX, but when I attempt to send it on windows I'm getting the following error:

Uncaught (in promise) DOMException: GATT operation failed for unknown reason.

Here is the code I'm using to send the string and convert it:

        event.target.writeValue(str2ab(":100000000C9434000C943E000C943E000C943E0082*"));

Here is my str2ab function:

 function str2ab(str) {

  var buf = new ArrayBuffer(str.length*2); // 2 bytes for each char

  var bufView = new Uint16Array(buf);

  for (var i=0, strLen=str.length; i<strLen; i++) {

    bufView[i] = str.charCodeAt(i);

  }

  return buf;

}

So it looks like for windows you have a 20 byte limit.

To correct the issue I'm using a write buffer and recursively going over it until all the bites have been written. Here is the code.

function writeBuffer(string) {

  writeOut(string, 0);

}



function writeOut(string, start) {

  if(start >= string.length) return;

  myCharacteristic.writeValue(str2ab(string.substring(start, (start+20)))).then(foo => {

    writeOut(string, (start+20));

  });

}