STM32F407 - HSE Bypass using external clock.

[Wood.Andy]

Hi

I wish to use an external clock into PH0 from an oscillator module already present in my design.

Does this mean PH1 becomes a spare pin?

Thanks

Andy.

[Uwe Bonnes]

HSEBYP needs HSEON and HSEON withh use PH0/1. I fear you can't use PH1 with external HSE. Perhaps try do some experiments . Perhaps PH1 is usable as Input pin.

[Wood.Andy]

Hi Uwe

Will probably have to give it a try if I don't get a definite answer.

Thanks

Andy.

[waclawek.jan]

RM0090 clearly says:

The external clock signal (square, sinus or triangle) with ~50% duty cycle has to drive the OSC_IN pin while the OSC_OUT pin should be left HI-Z.

Also ch.8.3.14 Using the OSC_IN/OSC_OUT pins as GPIO PH0/PH1 port pins says that PH0/PH1's GPIO is overridden when HSEON is set.

But of course an experiment is worth thousand words.

JW

[PVand.9]

I have the same situation on a NucleoL053 where a 8MHz signal is supplied to the STM32L053 on the PH0 pin. The PH1_pin seems not to be controllable and stays Hi_Z.

[Tesla DeLorean]

STM32L072CZ PH1 not a GPIO w/BYPASS

Ran into this with the Grashopper LoRa board, see this thread for context

https://community.st.com/s/feed/0D50X00009bLS7uSAG

[waclawek.jan]

Cross-post (and a different family, too) https://community.st.com/s/question/0D50X0000BSaGTsSQN/can-i-use-ph1-as-gpio-if-i-config-ph0-as-hse-bypass-clock-sourcethe-same-question-on-pc14-pc15-for-lsemy-chip-is-stm32h-seriies-tks-adv