Enable the Master Clock Output (MCO) in Non-Secure Region

abubakar · ‎2025-09-08

Hi all,

I’m working with the W5500 Ethernet module over SPI on an STM32 with Trust-zone enabled. The W5500 requires a clock source for proper operation, which I’m trying to provide using the MCO on the CS pin.

The issue is that I’m not able to enable the Master Clock Output (MCO), neither in the secure project nor in the non-secure project using CubeMX. Because of this, I can’t feed the required clock to the W5500.

Has anyone managed to enable MCO in a Trust-Zone setup, or know if there’s a specific way to configure it so that it works in the non-secure region?

Thanks for any help!

Bubbles · ‎2025-09-10

Hi @abubakar,

in pinout view, simply click on the pin on which you want the MCO enabled and select the function. Then in the clock tree you can select the clock for that MCO.

BR,

J

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