Resonator on STM32 board design failed...Or maybe not the design? Did I miss something? Help is needed::::::SOLVED!!!!!!!!!!

[TAlle.1]

Hello everyone,

I designed my own board which partly failed.

I used 32768 Hz ceramic crystal for LSE and 8MHz ceramic resonator for HSE.

I can upload my code successfully, but, it doesn't execute unless I disable both LSE and HSE.

I'm not professional designer, but, I carefully followed the design recommendations in AN2867.

My resonator is exactly as st recommends 8MHz with 33pF C_load. please check the pics below.

Y41 MC-146 32.7680KA-A3

Y42 AWSCR-8.00CELA-C33-T3

I have a Murat 16MHz resonator which lying around, so I gave a try, but with no luck.

Can someone help me? Any suggestions are really appreciated !

Regards,

Tommy

[TDK · Accepted solution]

R41 is way too high. I imagine shorting it would get things to work, but I didn't do the math to determine if it's okay.

https://www.st.com/resource/en/application_note/cd00221665-oscillator-design-guide-for-stm8afals-stm32-mcus-and-mpus-stmicroelectronics.pdf

[TAlle.1]

Thank you for taking your time reading my question!

Maybe you're right because all the documentation which I read says nothing about the R ext resistor (which in my case is R41).

The only thing which mentions it is the HSE current.

With some calculation I found it should be something around 3.3K? Am I right?

[TAlle.1]

SOLVED!

Great thanks to TDK and his advice. Replacing Y41 with 3.3 K solved the problem.

It's sure any another value around 3.3 K should work also as long as the HSE current is around 1mA.