Hello Team,
We are currently investigating an issue related to the SPI communication between the STPM34 sensor and the STM32F4 microcontroller.
At system startup, all values measured by the STPM34 remain stuck at zero. Even when voltage and current are injected using an OMICRON test bench, no measurement values are received or displayed.
Several tests were performed:
- If we power up the system and confirm that the issue is present, then electrically restart only the board containing the STPM34, the communication recovers correctly and the measured values are no longer stuck at zero.
- We also soldered wires on one of the SPI buses (SPI1). Since there are two STPM34 devices on the board, two SPI instances are used to communicate with each sensor. The purpose was to verify whether the communication between the sensor and the STM32 was correctly established.
- Interestingly, simply soldering wires on this SPI bus makes the issue disappear for this instance. However, on the second SPI instance, which was not modified, the issue is still present.
After reviewing the STPM34 datasheet, we noticed that in section 5 – Typical Application Example, resistors and capacitors are recommended on the communication lines. Currently, these components are not implemented on this board.
Could the absence of these recommended resistors/capacitors on the SPI lines explain this startup communication issue or unstable behavior with the STPM34?
Thanks,
Aymen
