STM32WL with HSE and XTAL

[s54mtb]

I am trying to start HSE with external crystal (on nucleo WL55JC1 board). I removed R2 (Output from TCXO), added two 0E bridges R39 and R40, added 10k resistor R41 (to remove stub).

Then I started the Cube-MX (latest, fresh update...), selected the nucleo WL55 from the board selector, initialized the periphery with board, changed RCC HSE settings to Crystal/Ceramic Resonator and changed the clock configuration to

 

When I compile and debug the project generated by Cube, the execution quits in error handler when the __HAL_RCC_GET_SYSCLK_SOURCE() is called (stm32wlxx_hal_rcc.c, line 347). The HSE status in RCC Control register remains 0 (HSE not ready).

Then I checked ref. manual and set all registers "by hand", using only CMSIS calls to enable HSE without success either.

With "out of factory" Nucleo setup (TCXO) and settings to use TCXO, everything runs normally.

Is there anything else I am missing here? Is there working example with STM32WL or WLE using external XTAL ?

Thanks!

Marko

[IREMI.1]

Hi Marko, sorry people that could answer such question are currently on vacation, back mid august.

[s54mtb]

Hi IREMI.1. Thank you for the response.

Meanwhile I found out the crystal I have in my circuit has 80 ohm ESR (more than max. ESR required by datasheet). Added 1M ohm parallel resistor and the oscillator works now.

Hope this is proper solution.

Regards,

Marko

[Amel NASRI]

Hi @s54mtb​ ,

Glad to know that you found a workaround for your issue.

To double check it, I suggest you to refer to AN5042 Precise HSE frequency and startup time tuning  for STM32 wireless MCUs.

-Amel