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Nucleo-144 STM32H755ZI vs STM32F767ZI

lserrnt
Associate II

Hey there,

I am facing a problem with the clocks on the STM32H755ZI. When I let a timer run at 50 kHz I get only smt. like 49.92 kHz out of it with sigma = 13 Hz. So there is at any frequency a steady offset of -1.2% and a sigma deviation of 0.03%. I have chosen as HSE the Crystal/Ceramic Resonator and the APB2 of the timer runs at 200 kHz.

lserrnt_0-1694156704155.png

With the Nucleo 144 STM32F767ZI I get for similar settings basically 0% frequency offset and sigma deviation of only 0.0003%. So I am wondering what has changed between these discovery boards

H755:

lserrnt_1-1694156832487.png

https://www.st.com/en/evaluation-tools/nucleo-h755zi-q.html

 

F767:

lserrnt_2-1694156898240.png

https://www.st.com/en/evaluation-tools/nucleo-f767zi.html

they both have this X4 crystal at 25.000 MHz and several others.

So do you see any way how I can achieve a higher frequency stability? Or what I might have to change in CubeIDE to activate a more accurate crystal on the H755 board? 

Thanks a lot for any help :)

14 REPLIES 14

I will recheck in future with an external crystal as X2. Thank you for your help :)

hello.How can i program the STLINK to output 8.33MHz? 

KevinNapier_0-1717746225557.png

program in here?

thx.

Kevin

Peter BENSCH
ST Employee

@KevinNapier For 8.33MHz, you must reprogramme the ST-LINK with the corresponding option during the ST-LINK firmware update.

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

H743 Upgrade.png

KevinNapier
Associate II

Compris. Merci beaucoup.