LoRaWAN

LoRaWAN implementation with temperature, humidity, and CO2 sensor / display based on LilyGo T-Echo, LoRaWAN gateway RAK7246G / RAK5146, TTN, and Datacake

Project plan

1. connect temperature / humidity sensor SHT31 to T-Echo Lite ==> achieved
2. show the measurements on the display of T-Echo Lite ==> achieved
3. configure the gateway ==> achieved
4. register the gateway in TTN ==> achieved
5. create application in TTN and get the TTN keys for the end device ==> achieved
6. extend the code on T-Echo Lite about LoRaWAN implementation (device activation, measurement upload) ==> achieved
7. Connect an IoT data dashboard to the data in TTN (with Datacake) ==> achieved
8. implement sleep mode with RAM retention for nRF52 ==> achieved
9. complete the sensor set to full air quality monitoring ==> started

1. Connect sensor to T-Echo

• connect SHT31 to T-Echo Lite using the following pins

Sensor pin	T-Echo pin	Arduino pin
VCC	3V3	3.3V power
GND	GND	Ground
SDA	P1.03 (PI.03)	35
SCL	P1.04 (PI.04)	36

2. Show measurements on T-Echo

• achieved with "Sensor connected" submission to GitHub

3. Configure gateway

• configure gateway network, internet access, LoRa band, TTN network

RAK7246G / RAK7248G:

• RAK7246G Quick Start Guide
• RAK7246G Quick Start Guide
• verify / change the TTN server name to new TTN V3 name (assuming EU1 selected in gateway setup in TTN; check the gateway configuration in general settings in TTN console; s. chapter Register gateway in TTN; assuming ask-it as organization name): ask-it.eu1.cloud.thethings.industries
• enable and restart LoRa services (assuming service name ttn-gateway): sudo systemctl enable ttn-gateway | sudo systemctl start ttn-gateway | sudo systemctl status ttn-gateway
• verify communication of the gateway with TTN: sudo journalctl -u ttn-gateway -f
• verify gateway connectivity status in TTN console (should be Connected)

RAK5146 PiHAT Kit for LoRaWAN and Concentrator (SPI model)

• referenced documentation:
  • 1. RAK5146 Setup with LoRa Basic Station
  • 2. Setting Up a LoRa Gateway with Raspberry Pi and RAK5146
  • 3. RAK Common for Gateway
  • 4. RAK2287 Quick Start Guide
• RAK PiOS approach chosen:
  • image download
  • Quick start guide
  • 1. flash the image
  • 2. initial boot / reboot
  • 3. startup with WiFi AP mode
  • 4. change network configuration
  • 5. post-installation steps (update, upgrade and reboot)
  • 6. install / update rakpios-cli
  • 7. select UDP packet forwarder, change the server name in environment variables, update the garteway EUI in TTN
  • 8. start the service and observe the logs in cli / connectivity status in TTN

4. Register application and gateway in TTN

• register application with TTN (outdated, still helpful)

  • RAK7246G LoRaWAN Network Server Guide

• register the gateway with TTN (outdated, still helpful)

  • RAK7246G LoRaWAN Network Server Guide

• create organization and application in TTN (outdated, still helpful)

  • Setup LoRaWAN Network in TTN

• register gateway in TTNS (helpful, but related to TTN gateway)

  • Setup LoRaWAN gateway on TTN Gateway Pro
    • for RAK LoRa gateway: ensure disabling authenticated connection

5. Get TTN device keys

• create a custom end device in TTN console (application section)
  • JoinEUI: enter 00 00 00 00 00 00 00 00
  • DevEUI: use generate button to create new device ID
  • AppKey: use generate button to create new application key
  • configure CayenneLPP decoder for end-device
• select LoRa parameters
  • LoRa version 1.0.3 (works with RadioLib)
  • bandwith plan according to region e.g., EU 863-870 SF90 RX2

6. Send measurements to TTN

• use RadioLib in LoRaWAN mode
  • implement OTAA (over the air activation) of the T-Echo
    • using the JoinEUI, DevEUI, AppKey, NwkKey (same as AppKey)
• use CayenneLPP library to create LoRaWAN paylod
• hint: for development purposes only change the settings of the end device in Join settings: Resets join nonces - Enabled

7. Connect Datacake with TTN to visualize the measurement data

• create a Datacake account
• add a new device:
  • create a new product
  • select TTN V3 as network server
  • enter device EUI and ID exactly from TTN
  • select free data plan
• change configuration of the new device
  • product and hardware:
    • adapt the payload decoder (hint: use use rawPayload, not payload data)
    • create fields TEMPERATURE, HUMIDITY, VOLTAGE (Numeric with appropriate semantic), LOCATION (Location type and sematic)

function Decoder(bytes, port) {
    var measurements = [];
    
    try {
        // Bei TTN-Integrationen in Datacake liegen die Webhook-Daten in rawPayload
        if (typeof rawPayload !== 'undefined' && rawPayload.uplink_message) {
            
            // 1. Sensordaten aus dem Decoded Payload auslesen
            if (rawPayload.uplink_message.decoded_payload) {
                var dec = rawPayload.uplink_message.decoded_payload;
                
                if (dec.temperature_1 !== undefined) {
                    measurements.push({ field: "TEMPERATURE", value: dec.temperature_1 });
                }
                if (dec.relative_humidity_2 !== undefined) {
                    measurements.push({ field: "HUMIDITY", value: dec.relative_humidity_2 });
                }
                if (dec.analog_in_3 !== undefined) {
                    measurements.push({ field: "VOLTAGE", value: dec.analog_in_3 });
                }
            }
            
            // 2. GPS-Position sicher auslesen (falls in TTN Registry gesetzt)
            if (rawPayload.uplink_message.locations && rawPayload.uplink_message.locations.user) {
                var lat = rawPayload.uplink_message.locations.user.latitude;
                var lon = rawPayload.uplink_message.locations.user.longitude;
                
                if (lat !== undefined && lon !== undefined) {
                    measurements.push({ 
                        field: "LOCATION", // Muss exakt wie dein Geo-Feld in Datacake heißen
                        value: "(" + lat + "," + lon + ")" 
                    });
                }
            }
        }
    } catch (e) {
        // Fehler abfangen, damit der Decoder nicht abstürzt
    }
    
    return measurements;
}

8. Implement power saving mode for T-Echo Lite

• implement sleep mode with RAM retention for nRF52
  • considering only uplink to TTN for RadioLib
  • using the 2min cycle implemented in measurement upload to TTN / Datacake
  • solution:
    • delay() in loop()
    • custom delay for RadioLib

9. Add CO2 sensor for full air quality monitoring

• add SCD40 sensor to I2C bus
  • follow the connecvtivity plan in 1.
• extend the software to handle multiple sensors
  • introduce automatic detection of supported sensor types
  • add CO2 concentration to CayenneLLP payload
• adapt the Datacake configuration (fields, decoder)