This guide will instruct you to create a codec for a LoRaWAN node to decode uplinks in Easy LoRaWAN Cloud.
- Easy LoRaWAN Server: https://lorawan.easylorawan.com
- Codec repository: here
- The uplink data is in field data with Base64 format. We need to decode the data into object with readable values.
1. Sample codecs for commercial LoRaWAN Nodes
Step 1.1: Sample codecs are collected here
Step 1.2: (Optional) If you have a codec for TTNv2 or ChirpStack v3, you need to put the below wrapper function to convert a codec to ChirpStack v4.
// TTNv2
function Decoder(bytes, port) {
...
}
// TTNv2 to V4 converter
function decodeUplink(input) {
return {
data: Decoder(input.bytes, input.fPort)
};
}
// 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)
};
}2. To create a custom codec if a sample codec is not available
Step 2.1: We need to decode uplink data into required JSON format for Easy LoRaWAN Cloud.
- To choose “Custom JavaScript codec functions”.
- To populate the function decodeUplink(input).
- To check sample codecs for hints.
Step 2.2: We can use the below codec as a starting point to convert bytes into a JSON object.
- To convert bytes into other format, you can check this guide.
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}};
}Step 2.3: After a successful decode, we will see the decoded value in “object”.
Done.
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How can I convert bytes into float?
Thanks a lot.
Hi William,
You can look at this guide.
We have sample converters to convert from byte array to integer, float and double.
Hope it helps.
https://iotthinks.com/common-converter-for-decoder-script/