Zephyr on 96Boards WisTrio IoT Board

Manivannan Sadhasivam


Hello and Welcome to the blog, Zephyr on 96Boards WisTrio IoT Board. This blog gives a quick summary of the recent upstreaming efforts for WisTrio IoT board in Zephyr Project.

WisTrio IoT Board

WisTrio IoT board is the first LoRa tracker board in 96Boards IoT form factor from RAKWireless. This board is based on the RK5205 chipset comprising of STM32L1x MCU and SX1276 LoRa modem. This board is a perfect bet for developing low-cost LoRa nodes for IoT applications. Below are some of the key features of this board:

  • Chipset: RAK5205
  • Interface: I2C, GPIO, UART, ADC
  • LoRa band: Supports multiple global bands
  • GPS module integrated
  • Antennas: LoRa antenna and GPS antenna
  • Working voltage: 3.3v
  • Flash: 128 KB
  • RAM: 16 KB

On board sensors:

  • Acclerometer: STMicro LIS3DH
  • Integrated Environmental sensor: Bosch BME680

Zephyr support for WisTrio IoT board

RAKWireless provides a LoRa based Demo project for using this board. It is a good starting point for getting hands on with LoRa technology. But since we are standardizing Zephyr as the software platform for all of our IoT boards, I decided to port this board to Zephyr. The chipset RAK5205 is based on the STM32L151 MCU from ST Microelectronics. So, I assumed that porting this board/chipset is going to be very easy since ST is an active contributor to Zephyr project.

But when I looked into the SoC support for STM32L1x series, there was none existed. So, I took the courage to add the STM32L1x SoC series support with the STM32Cube HAL for supporting the MCU on this board. It took me one day to add both SoC and board support in Zephyr.

Note: Kudos to the ST folks working on Zephyr, because they made it very easy to add a new SoC series to Zephyr

But I observed something unusual while working on this project. Usually, I have to debug the new board/SoC support using SWD debugger to get it working. But on this board, it just worked straight away when I flashed the sample Hello world project!!!

So after adding the README doc and cleaning up the commits, I submitted the Pull Request to Zephyr.



While the PR is under review, now I’m thinking of implementing the LoRa API support in Zephyr. This will enable us to use this board as a full-fledged LoRa node running Zephyr. But this will take a while and might involve efforts from multiple people. Stay tuned!

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