# Compatible codecs for Easy LoRaWAN Cloud
The codecs will be used in this guide: https://iotthinks.com/add-a-lorawan-device-in-to-easy-lorawan-cloud/
- The codecs in this folder is COMFIRMED to work with Easy LoRaWAN Cloud

The below sample codecs are from external repositores and required to be fixed before using in Easy LoRaWAN Cloud.
- From TTN: https://github.com/IoTThinks/lorawan-devices/tree/master/vendor
- From Dragino: https://www.dropbox.com/sh/sa4uitwn6xdku9u/AACUA890oj5dl8rETYO2icdBa?dl=0
- From RAK Wireless: https://github.com/RAKWireless/RAKwireless_Standardized_Payload

### Codec Format
A valid codec for Easy LoRaWAN Cloud is below:
```
// Decode uplink function.
//
// Input is an object with the following fields:
// - bytes = Byte array containing the uplink payload, e.g. [255, 230, 255, 0]
// - fPort = Uplink fPort.
// - variables = Object containing the configured device variables.
//
// Output must be an object with the following fields:
// - data = Object representing the decoded payload.
function decodeUplink(input) {
  var bytes = input.bytes;
  
  var BatV = (bytes[0] << 8 | bytes[1]) / 1000 + 0.277;
  var PayVER = bytes[2];
  // If AT+DATAUP=1, PayloadCount=1 byte, payload#=1 byte
  var Temp = (bytes[3] << 8 | bytes[4]) / 10;
  var Humid = (bytes[5] << 8 | bytes[6]) / 10;
  
  return {"data": {"BatV":BatV, "PayVER":PayVER, "Temp":Temp, "Humid":Humid}};
}

// Encode downlink function.
//
// Input is an object with the following fields:
// - data = Object representing the payload that must be encoded.
// - variables = Object containing the configured device variables.
//
// Output must be an object with the following fields:
// - bytes = Byte array containing the downlink payload.
function encodeDownlink(input) {
  return {bytes: []};
}
```

### Conversion of Codec Formats
If you have a codec for ChirpStack v3, you need to put the below wrapper function to convert a codec to ChirpStack v4.
Easy LoRaWAN uses ChirpStack v4

```
// V3
function Decode(fPort, bytes, variables) {
   ...
}

// V3 to V4 converter
function decodeUplink(input) {
   // Wrapper function for ChirpStack v4
   return {
      data: Decode(input.fPort, input.bytes, input.variables)
   };
}
```