Reset one STM32 MCU using another STM32 MCU via NRST Pin.

[SayanSeth]

Hi,

I'm trying to reset one STM32 MCU using another STM32 MCU via NRST Pin. I'm pulling down that NRST Pin using GPIO Output Pin of Host MCU. In this case what should be the GPIO configuration (Push-Pull/Open Drain)(No Pull Up Pull Down/Pull Up).

Same question is for changing Boot Mode of slave MCU using master MCU via BOOT0 Pin.

[Tesla DeLorean]

The NRST pin should have an internal pull-up. You should only even drive it Open-Drain/Collector as it is a bi-directional signal. ie internal POR and software reset methods can drive it. ARM processors will usually fail if the NRST pin is DRIVEN HIGH.

BOOT0 can use push-pull, I'd recommend an external pull-down to ensure the FLASH is used to run code in the nominal case.

[berendi]

Ensure that MCU2 (which resets MCU1) is always powered while MCU1 is on, otherwise it will pull the reset pin of MCU1 low.