STM32L431RCT reads out Zero Value from ADC after EMC/ESD Testing. After a manually disable and enabling adc cycle everything is fine again.

[MGehr.3]

Do you have any ideas what's going on with STM32L431RCT. After ESD Testing ADC of STM32L431RCT reads back 0 Values at all Input Channels. A manually disable and enabling cycle in debugging mode helps. ADC is reading values then correct again.

We also checked ADC Registers(ADC Mode, Channel Selection and so on). But everything looks fine. Only the read back ADC Value are on all channels Zero :-(. . Any ideas what did happen? I can repeat this bahavour pretty well :-)! Thany you in advance for your feedback/help!

[Dvorak.Peter]

Try reading the following notes:

https://www.st.com/resource/en/application_note/cd00004479-emc-design-guide-for-stm8-stm32-and-legacy-mcus-stmicroelectronics.pdf

https://www.st.com/resource/en/application_note/dm00548138-fundamentals-of-esd-protection-at-system-level-stmicroelectronics.pdf

Your problem is not limited to the ADC readings.

You will need to change your schematic, PCB layout , packaging, grounding, shielding or external filtering

There is no software fix for this problem.

[MHAJJ]

What are the pins used for the ADC read ? I gave the attached photo an extra look and the PA1 isn't connected, same for PA12. If the ADC pin is close to those unconnected pins maybe a change in their GPIO config may help, also maybe adding protection there too. I'm just thinking that an unconnected pin close to the ADC may be the disturbance path.

Regards,

Mahmoud.