Generate a 20 MHz clock with the GPIO outputs in STM320H745zi

[ABlum.2]

Hello everyone!

Is there any project to generate an Clock output of 20Mhz? I tried with TIM 16 but the best I can get is around 300 kHz

Thanks in advance

Alan Blumenstein

[Mike_ST]

In the STM32H7 firmware package,

available here:

https://www.st.com/en/embedded-software/stm32cubeh7.html

you have a PWM example \Projects\NUCLEO-H745ZI-Q\Examples\TIM\TIM_PWMOutput

and then it's a matter of adjusting uhPrescalerValue, PERIOD_VALUE and PULSEx_VALUE

[ABlum.2]

Hi Mike_ST

Thanks for the response. I tried to play with this example before and I am not reaching the 20 MHz, I also tried to use an interruption were I set a digital output to generate the clock but the frequency drop down to 400 kHz.

Regards

Alan

[Javier1]

Are you using a XTAL as a HSEclock source?

How high is your system clock?

Maybe share a snap of your cubeMX page clock setup

[ABlum.2]

Hi Javier,

Thanks for the answer here I send you a picture of the clock setup.

[Tesla DeLorean]

Sounds like you're trying to service an update interrupt rather than let the TIM control the pin directly. ​

[ABlum.2]

Hi Tesla Delorean

Thanks for the answer. Yes the pin I need to control is not realted to any TIM (pin PC2_C) hence I need to toggled it to make the clock.

Regards

Alan

[Javier1]

@ABlum.2​ That pin has the DFSDM1_CKOUT option.I never used this peripheral but its meant for driving external ADCs so the DFSDM1_CKOUT pin can generate a very fast pwm clock signal for you.

 

Did you tried this already?