STM32L4 - are pullups during reset active when RDP level is 2?

[ramses946]

Citing from the STM32L431 manual:

The debug pins are in AF pull-up/pull-down after reset:
• PA15: JTDI in pull-up
• PA14: JTCK/SWCLK in pull-down
• PA13: JTMS/SWDAT in pull-up
• PB4: NJTRST in pull-up
• PB3: JTDO in floating state no pull-up/pull-down

Let's take PA15 as an example. What happens if RDP level is set to level 2 (debug interface disabled). Will the debug pin pulls still be active?

[Pierre_Paris · Accepted solution]

Hello @ramses946,

In the RDP level 2 (No Debug), JTAG & SWD connection is killed, you can't use it.

However, until the IO is not reconfigured, reset value is applied as follow:

- GPIOA_MODER = 0xABFF FFFF (So, PA15 in Alternate Funtion mode)

- GPIOA_PUPDR = 0x6400 0000 (So, PA15 in Pull-up)

If you want to use the GPIO, you can configure it through your application.

Best Regards,

Pierre

[ramses946]

Okay, the reason I asked was that I want to use this pin to bias the gate of an external P MOSFET (switch it off during reset).

So it seems that this pin can be used for this purpose even in RDP2.