payload Formats

function Decoder(bytes, port) {
  return {
    // GPS coordinates; signed 32 bits integer, MSB; unit: °
    // When power is low (<2.84v), GPS won’t be able to get location
    // info and GPS feature will be disabled and the location field
    // will be filled with 0x0FFFFFFF, 0x0FFFFFFF. 
	
    Latitude: 
      (bytes[0]<<24 | bytes[1]<<16 | bytes[2]<<8 | bytes[3]) / 1000000,
	  
    Longitude:
      (bytes[4]<<24 | bytes[5]<<16 | bytes[6]<<8 | bytes[7]) / 1000000,


    // Alarm status: boolean
    ALARM_status: (bytes[8] & 0x40) > 0,

    // Battery; 14 bits; unit: V
    BatV: ((bytes[8] & 0x3f)<<8 | bytes[9]) / 1000,

    // Motion detection mode; 2 bits
    MD: {
      "0": "Disable",
      "1": "Move",
      "2": "Collide",
      "3": "Custom"
    }[bytes[10]>>6],

    // LED status for position, uplink and downlink; 1 bit
    LON: (bytes[10] & 0x20) ? "ON" : "OFF",

    // Firmware version; 5 bits 
    FW:150+(bytes[10] & 0x1f),

    // Roll; signed 16 bits integer, MSB; unit: Â

    // Sign-extend to 32 bits to support negative values: shift 16 bytes

    // too far to the left, followed by sign-propagating right shift

    Roll: (bytes[11]<<24>>16 | bytes[12]) / 100,

    // Pitch: signed 16 bits integer, MSB, unit: Â

    Pitch: (bytes[13]<<24>>16 | bytes[14]) / 100,
  };
}