Milesight WS101: LoRaWAN SOS & Smart Button

function decodeUplink(input) {
  var bytes = input.bytes;
  var data = {};

  for (var i = 0; i < bytes.length; ) {
    var channel = bytes[i++];
    var type = bytes[i++];

    if (channel === 0x01 && type === 0x75) {            // battery (%)
      data.battery = bytes[i]; i += 1;
    } else if (channel === 0xff && type === 0x2e) {     // press event
      data.button_event = readButtonEvent(bytes[i]); i += 1;
    } else if (channel === 0xff && type === 0x01) {     // IPSO version
      data.ipso_version = bytes[i]; i += 1;
    } else if (channel === 0xff && type === 0x09) {     // hardware version
      i += 2;
    } else if (channel === 0xff && type === 0x0a) {     // firmware version
      i += 2;
    } else if (channel === 0xff && type === 0x0b) {     // device status
      i += 1;
    } else if (channel === 0xff && type === 0x0f) {     // LoRaWAN class
      i += 1;
    } else if (channel === 0xff && type === 0x08) {     // serial number
      i += 6;
    } else {
      break;
    }
  }
  return { data: data };
}

function readButtonEvent(v) {
  if (v === 1) return "short press";
  if (v === 2) return "long press";
  if (v === 3) return "double press";
  return "unknown";
}

function readUInt16LE(b, i) {
  return (b[i + 1] << 8) | b[i];
}