STM32MP257F-EV1: No oscillation on X1 and X2 crystals, X7 (ST-LINK, 24 MHz) working correctly

[Radha Kadam]

Dear ST Support Team,

I am working with the STM32MP257F-EV1 evaluation board and have found an issue with some of the on-board crystals while checking their clock frequencies.

Observations:
- X1: no frequency is observed
- X2: no frequency is observed
- X7 (ST-LINK crystal): a correct frequency of 24 MHz is observed again

Could you please help me with the following:
1. Possible reasons why X1 and X2 are not oscillating on this board.
2. Any recommended checks (supply, load capacitors, bias, probing method) to confirm whether this is a hardware fault or a measurement issue.
3. Whether this could be a defective board, and if so, the process for replacement or repair.

I can share measurement screenshots, photos of the board, and further details if needed.

Thank you for your support. I look forward to your reply.

Best regards,
Radha
 

[Peter BENSCH]

Have you looked at the schematics?
What did you find at X2 (keyword R70)?
With what, and how, did you measure the oscillation at X1?
Are you aware that X1 is a very sensitive LSE?

Regards
/Peter

[Radha Kadam]

Hi Peter,

Thank you for your quick reply.

Yes, I have gone through the STM32MP257F-EV1 schematics from the CAD resources page.

• X2: I checked at C90 and R75 and saw no signal. I have not checked R70 yet, and I will do that now and report back.
• X1: I measured at R64 using a 10x passive probe.
• LSE sensitivity: I understand that X1 is the 32.768 kHz LSE and is very sensitive to loading. A 10x probe adds a lot of capacitance, so it may have stopped the oscillation. I will re-measure with a 10x or low-capacitance probe, or check the LSE through software (the LSE ready flag).

Regards,

Radha

[PatrickF]

Hi ​@Radha Kadam 

 

Maybe precise what issue you face which make you suspecting a crystal oscillation issue.

 

HSE (40MHz) and LSE (32.768kHz) are not started upon reset.
For instance, if boot pins are in ‘development boot’, you might not see any oscillation.
During USB DFU boot, only HSE is started by the BootROM (to clock USB).

 

Please try starting Linux Starter Package and check again.
https://wiki.st.com/stm32mpu/wiki/Getting_started/STM32MP2_boards/STM32MP257x-EV1/Let%27s_start/Populate_the_target_and_boot_the_image
 

I also warn that probing a crystal oscillator might stop oscillation if not done with adequate material (too much load or noise injection).

Regards