decoder.js

function Decoder(b, port) {
var decoded = {};
    switch (port) {
        case 2:
            decoded.lat = ((b[0]<<16)>>>0) + ((b[1]<<8)>>>0) + b[2];
            decoded.lat = (decoded.lat / 16777215.0 * 180) - 90;
            decoded.lon = ((b[3]<<16)>>>0) + ((b[4]<<8)>>>0) + b[5];
            decoded.lon = (decoded.lon / 16777215.0 * 360) - 180;
      
            var altValue = ((b[6]<<8)>>>0) + b[7];
            var sign = b[6] & (1 << 7);
            if(sign)
            {
                decoded.alt = 0xFFFF0000 | altValue;
            }
            else
            {
                decoded.alt = altValue;
             }
            decoded.hdop = b[8] / 10.0;
        
        break;
        
        case 3:
            decoded.bat = (b[0] | b[1]<<8 | (b[1] & 0x80 ? 0xFF<<16 : 0)) * 10.0;

        break;
    
        case 4:
            decoded.aX = (b[0] | b[1]<<8 | (b[1] & 0x80 ? 0xFF<<16 : 0));
            decoded.aY = (b[2] | b[3]<<8 | (b[3] & 0x80 ? 0xFF<<16 : 0));
            decoded.aZ = (b[4] | b[5]<<8 | (b[5] & 0x80 ? 0xFF<<16 : 0));

        break;
}

return decoded;
}