Milesight WS156: LoRaWAN E-Ink Smart Scene Panel

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 === 0x34) {   // button press + D2D command
      var id = bytes[i];
      data["button_" + id] = 1;
      data["button_" + id + "_d2d"] = toHex16(readUInt16LE(bytes, i + 1));
      i += 3;
    } else if (channel === 0xff && type === 0x01) {   // protocol/IPSO version
      data.ipso_version = "v" + (bytes[i] >> 4) + "." + (bytes[i] & 0x0f); i += 1;
    } else if (channel === 0xff && type === 0x16) {   // serial number (8 bytes)
      data.sn = toHexStr(bytes, i, 8); i += 8;
    } else if (channel === 0xff && type === 0x0f) {   // LoRaWAN class
      data.lorawan_class = ["A", "B", "C", "CtoB"][bytes[i]] || "unknown"; i += 1;
    } else if (channel === 0xff && (type === 0x09 || type === 0x0a)) { // hw/fw version
      i += 2;
    } else if (channel === 0xff && (type === 0xfe || type === 0x0b)) { // reset / device status
      i += 1;
    } else {
      break;
    }
  }
  return { data: data };
}

function readUInt16LE(b, i) {
  return ((b[i + 1] << 8) | b[i]) & 0xffff;
}
function toHex16(v) {
  return "0x" + ("0000" + v.toString(16)).slice(-4);
}
function toHexStr(b, i, len) {
  var s = "";
  for (var k = 0; k < len; k++) s += ("0" + (b[i + k] & 0xff).toString(16)).slice(-2);
  return s;
}