Decode Data and Bytes

ChirpStack Application Server
1

Hello Every one,
I don’t know why I want to decode “bytes”, but the function Decode(fPort,bytes) decode “data”.

2

Hi

The Bytes is in an array, bytes[0] etc…

with a temp sensor for dragino

the decoding looks like this

function Decoder(fPort, bytest) {
      // Decode an uplink message from a buffer
      // (array) of bytes to an object of fields.

      var value=(bytes[0]<<8 | bytes[1]) & 0x3FFF;
      var batV=value/1000;//Battery,units:V

      value=bytes[2]<<8 | bytes[3];

      if(bytes[2] & 0x80)
           {value |= 0xFFFF0000;}
      var temp_SHT=(value/100).toFixed(2);     //SHT20,temperature,units:℃

      value=bytes[4]<<8 | bytes[5];
      var hum_SHT=(value/10).toFixed(1);     //SHT20,Humidity,units:%

      value=bytes[7]<<8 | bytes[8];
      if(bytes[7] & 0x80)
           {value |= 0xFFFF0000;}
      var temp_ds=(value/100).toFixed(2);     //DS18B20,temperature,units:℃
      return {
                     BatV:batV,
                     TempC_DS:temp_ds,
                     TempC_SHT:temp_SHT,
                     Hum_SHT:hum_SHT
      };
}

That changes the “Data” key in the mqtt to more readable.

example.

data:"zDAM7gE2AX//f/8="
to
data:"zDAM7gE2AX//f/8=",object:{ BatV:3.12, Hum_SHT:"31.0", TempC_DS:"327.67", TempC_SHT:"33.10"}

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