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Associate III
Jun 4, 2025 12:15 PM UTC
Solved

STM32 Reset pin duration

Hi,
We are working with the STM32G491 board and intend to drive the NRST pin using an external device. Could you please confirm the minimum low-level pulse duration on the NRST pin for it to be recognized as a valid reset by the MCU?

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TDK
TDKBest answer
Jun 4, 2025 12:43 PM UTC

350 ns

TDK_0-1749041006257.png

 

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3 replies

TDK
TDKBest answer
Jun 4, 2025 12:43 PM UTC

350 ns

TDK_0-1749041006257.png

 

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Associate III
Jun 4, 2025 1:07 PM UTC

Hi @TDK ,
The external device controls both the BOOT and NRST pins of the STM32G491 MCU. According to the datasheet, the minimum low-level pulse duration on the NRST pin required to trigger a reset is 350 ns. If I hold the BOOT pin high and apply a 1 ms low pulse on the NRST pin, will the MCU recognize it as a valid reset and enter bootloader mode?

TDK
Jun 4, 2025 2:26 PM UTC

Yes, provided the BOOT0 pin state is not disabled in option bytes. See AN2606.

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