STM32N6: In HSE Bypass, can PH1 pin be configured as Input Output ?

matt-crc · ‎2026-02-26

Split from original question

Can you check your documentation ? According to RM086 - Reference Manual for STM32N657, all PH GPIOs can be set as input/output (contradicting your previous post).

Default State: When a crystal is used for the HSE (PH0/PH1), PH1 is dedicated to the oscillator output and cannot be used as a general-purpose I/O (GPIO).
Bypass Mode: When you configure the RCC (Reset and Clock Control) to "HSE Bypass," an external clock signal is fed directly into PH0 (OSC_IN), freeing up the PH1 pin to act as a standard GPIO.
Functionality: As a GPIO, it can be configured as a push-pull output.

Please retest your device and determine which document is correct.

thanks

Matthew

FBL · ‎2026-04-28

Hi @matt-crc

On STM32N6, PH0 and PH1 are input only as indicated in datasheet not like other products. Actually, these are limited to 1.8V instead of 3.3V

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Best regards,
FBL