Accomplishments

This week, I worked with Caitlyn for some of the FreeRTOS integration with the STM32WB55RG Nucleo board. However, I spent most of my time working setting up P2P BLE communication between the STM32 and ESP32.

We’re using the STM32CubeIDE for development on our STM32 board. This allows you to autogenerate configurations so that you don’t have to manually do things like writing a bootloader/RTOS, writing drivers for GPIO and communication protocols like UART, I2C, SPI, BLE, etc. However, there was an issue with getting both RTOS and P2P BLE communication working on the STM32. This is because the P2P code uses a sequencer that conflicts with the RTOS’s scheduler, and therefore the IDE cannot autogenerate code to support both. I saw that at least 2 ST employees have acknowledged this limitation in these 2 ST community forum posts: see post 1 and post 2.

Regardless, with the help of some of the documentation from one of the ST employees, I was able to replace the P2P sequencer code with similar RTOS kernel function calls. So far, the code at least builds and compiles fine. I have documented some of my learnings along the way, as well as the communication architecture for BLE between the ESP and STM in this Google doc.

Progress / Schedule

Currently, I would be a bit behind schedule. The FreeRTOS and P2P setup on both devices has been a challenge, as well as getting accustomed to the new development environment for the microcontrollers. However, I have learned how to debug on both devices via UART and GDB (at least the STM32IDE has a pretty decent GUI for GDB+print debugging), and I have also learned more about the BLE protocol.

In parallel, Caitlyn and I will be testing out some of the IMU sensors and haptic motors.

Deliverables / Next Steps

Next week, I will:

• Work on sending a stream of bytes from one MCU to another and validating with UART with minicom on my machine.
• Test BLE latency between the 2 devices using an oscilloscope via a sequence of GPIO set commands.
• Help with the setup and integration of sensors/motors.