Bangle 2. How to set GPS Serial1 baud rate?

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•

HughB
For Bangle 1 someone wrote this code - but I think the format is different for this chip.
```
function writeGPScmd(cmd) {
  var d = [0xB5,0x62]; // sync chars
  d = d.concat(cmd);
  var a=0,b=0;
  for (var i=2;i<d.length;i++) {
    a += d[i];
    b += a;
  }
  d.push(a&255,b&255);
  console.log(d);
  Serial1.write(d);
}
```
Also the DATASHEET has a different checksum method.

The checksum is the word-by-word of all data from field 2 to field 5 (including field 2 and >field 5) (1 word includes 4(Bytes) cumulative sum, occupying 4 bytes. The calculation of the >check value can follow the following algorithm:
```
ckSum = (class << 24) + (id << 16) + len;

for (i = 0; i <(len / 4); i++){
  ckSum = ckSum + payload [i];
}
```
Has anyone implemented this function so that you can send the CAS commands without having to work out the checksum by hand all the time.

•

Mark_M in reply to @HughB

Has anyone implemented this function so that you can send the CAS commands without having to work out the checksum by hand all the time.

yes, I've done.

AT6558.prototype.checksum = function(val) {
  var cs = 0;
  for (const c of val) {
    cs = cs ^ c.charCodeAt(0); //XOR
  }
  return cs.toString(16).toUpperCase().padStart(2, '0');
};

AT6558.prototype.sendCommand = function(command) {
  cmd = "P" + command;
  cs = this.checksum(cmd);
  cmd = "$" + cmd + "*" + cs;
  print(cmd);
  Serial1.println(cmd);
};

AT6558.prototype.setBaudRate = function(v) {
  var br = "";
  switch (v) {
    case 4800:
      br = "0";
      break;
    case 9600:
      br = "1";
      break;
    case 19200:
      br = "2";
      break;
    case 38400:
      br = "3";
      break;
    case 57600:
      br = "4";
      break;
    case 115200:
      br = "5";
      break;
    default:
      return;
  }
  this.baudRate = v;
  sendCommand("CAS01," + br);
};

Bangle 2. How to set GPS Serial1 baud rate?

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