Dear Sir/Madam,
We are using the STM32WLE5CCU6 LoRa MCU for our custom LoRa application project. We are able to detect the MCU successfully, and flashing/programming is also working without any issues.
However, with our LoRa application, we were initially unable to establish a link with the LoRa gateway. After investigation, we identified an issue related to the 32 MHz clock circuit. We replaced the crystal on our custom board with the crystal used on the STM32WLE5 evaluation board, and after this change the issue was resolved. We were able to communicate with the gateway, and packets were received correctly.
Later, we ordered the same evaluation board crystal again and assembled it on our board. However, this time we are once again unable to link with the gateway, even though the crystal part number is the same. This behavior is confusing, as the evaluation board crystal had previously worked on our board.
We would like to understand:
Is there any register or configuration option in the STM32WLE5 to tune or trim the external 32 MHz crystal?
We are able to observe the 32 MHz frequency toggling approximately every 15 ms on the scope — is this expected behavior?
Are there any recommended checks or guidelines for crystal load capacitance, startup time, or clock stability that could affect LoRa RF communication?
Could you please help us understand the possible root cause and guide us on how to resolve this issue?
Thank you very much for your support.
Best Regards,
Samudralankaiah Jampani
