Decode raw LoRaWAN uplink bytes from a cold-chain temperature sensor into structured data using a The Things Stack payload formatter

Steps

1. Register your LoRaWAN temperature sensor as an end device in a The Things Stack (Community Edition) application
2. Write a JavaScript decodeUplink(input) function that reads input.bytes and input.fPort and returns { data: {...}, warnings: [...] }
3. Add an optional normalizeUplink(input) function to map your decoder's output into the standard normalized schema, e.g. air.temperature in Celsius
4. Set the formatter via the Console (Application > Payload Formatters, or per-device), the CLI (ttn-lw-cli applications link set ... --default-formatters.up-formatter FORMATTER_JAVASCRIPT), or the REST API (PUT /api/v3/as/applications/{application_id}/link)
5. Confirm decoded output appears in the uplink message's decoded_payload field alongside the raw frm_payload when the device sends data
6. If your device model exists in the Device Repository, use FORMATTER_DEVICEREPO instead of writing a custom decoder