Update README.md

Codec/README.md

@@ -2,8 +2,43 @@
 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
 
-Reference: 
+The below sample codecs are from external repositores and required to be fixed before using in Easy LoRaWAN Cloud.
-- Sample codecs with TTN format: https://github.com/IoTThinks/lorawan-devices/tree/master/vendor
+- From TTN: https://github.com/IoTThinks/lorawan-devices/tree/master/vendor
-- Sample codec from Dragino: https://www.dropbox.com/sh/sa4uitwn6xdku9u/AACUA890oj5dl8rETYO2icdBa?dl=0
+- From Dragino: https://www.dropbox.com/sh/sa4uitwn6xdku9u/AACUA890oj5dl8rETYO2icdBa?dl=0
+- From RAK Wireless: https://github.com/RAKWireless/RAKwireless_Standardized_Payload
 
+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: []};
+}
+```