How to use the GPIO pin of the CN7 on the STM32N6570-DK board

[Z-YF]

I am working on a STM32N6570-DK board and I noticed that the CN7 of the board can be modified as digital I/O pin or an ADC. So I want to make sure that when I use the A1 port of CN7 for example, and I want to use this port as a usart_tx. Then I can directly enable the PC10 as a usart_tx and disable the PA9 right? And I want to make sure that the modification don't damage the ADC function of PA9, since the MCU actually accept 0-1.8V and the 3.3V is too high.

[Z-YF]

The arrangement of the ports are shown in the picture below.

[Andrew Neil]

The board schematics are available on the 'CAD Resources' tab of the Product Page:

https://www.st.com/en/evaluation-tools/stm32n6570-dk.html#cad-resources

[Z-YF]

Thanks for that .

And I concluded the circuit looks like the picture below. So if I want to use the digital pin and set it as an usart_tx, I can directly use it, right?(The amplifier turns the 0-3.3V into the 0-1.8V).

[RomainR. · Accepted solution]

Hi @Z-YF 

Your understanding of the diagram is correct.
If you plan to use CN7-A1 as USART1 digitally with VDD levels of 3.3V, the GPIO PA9 is protected by the AOP U8B and its input divider bridge (signal ARD_A1). When PC10 = 3.3V, PA9=1.8V. 

Best regards,

Romain,

[Z-YF]

OK， thank you for your time. :)