A simple demo to work with LoRaWAN that's compliant with Indonesia region. It reads air quality data (CO2 and TVOC) from SGP30 sensor, and transmit them over LoRaWAN.
For this project, I need to fork and modify a LoRaWAN library and posted it here: https://github.com/andriyadi/Beelan-LoRaWAN. By that, the LoRaWAN regional parameters complies with Indonesia's LPWA tech spec regulation, and the device may be able to connect with LoRaWAN public network in Indonesia, e.g: Antares platform and network server. You can use my modified library not only for the MCU I use here (STM32L1), but for other Arduino compatible MCU and boards (other STM32 MCU supported by STM32Duino, ESP32, SAMR34, NRF52, etc). The library is originally from here.
If you want to replicate this project without any modification, you need following hardware:
- DycodeX LoRa development board (contact me to get one). Or you can use any boards using RAK811 module but you may need to adjust some minor code.
- SGP30 sensor module. I use the one from Seeed Studio
- Optionally ST-Link for flashing the firmware and debugging. I set the PlatformIO configuration file to use ST-Link. If you want to use DFU or JLink uploader, adjust the config (.ini) file
- This project is developed using PlatformIO tooling. Make sure to install it.
- ST STM32 platform to work with STM32 MCU which powers the board. I use Arduino framework, which is based on STM32Duino project.
To publish data over LoRaWAN, obviously you need a LoRaWAN gateway. For this project, the gateway should be tuned to frequency plan for Indonesia. Or you can use public LoRaWAN network, such as Antares. Try to register and login, read their documentation.
To keep thing simple, and to easily work with Antares platform, I publish the data in string that only contain the value. Of course, you can and should use binary format, but there's no payload decoder in Antares for me to be able to display the data on a widget.
Since we have two data to transmit (CO2 and TVOC), to differentiate them I make use of port in LoRaWAN. CO2 is transmitetd using port 2, while TVOC on port 3. You can see in the code at this section:
if (loraTxCounter % 2 == 0) {
// CO2
actLen = snprintf(txData, 8, "%d", lastCO2);
...
lora.sendUplink(txData, strlen(txData), 0, 2); // using port 2
...
}
else {
// TVOC
actLen = snprintf(txData, 8, "%d", lastTVOC);
...
lora.sendUplink(txData, strlen(txData), 0, 3); // using port 3
...
}
In src/main_lora_iaq.hpp, adjust these constants according to your OTAA credentials:
// OTAA credentials
const char *devEui = "<CHANGE_THIS>";
const char *appEui = "<CHANGE_THIS>";
const char *appKey = "<CHANGE_THIS>";
As for my demo, I use Antares LoRaWAN network server, the published data end up in Antares platform. I still can not do much in term of data visualization. For further processing and visualization, we can integrate Antares with other platform, such as Node-RED.
Here's the capture of Node-RED flow to parse and process the data, the flow script is attached in assets/node-red_flows. I can use Node-RED dashboard pallete to visualize data, right from Node-RED.
- Beelan-LoRaWAN
- Antares sample code