STM32h755 Clock sync

[baselimadt]

Hi,

I am working on a product for one of my clients that included two MCUs (STM32h755) on the same board working together and he requested both MCUs to be run on the same time "same clock", to be synced together. could you please advise if it possible to add a clock generator IC to feed both MCUs same clock. if so, please suggest a component or a document that will help me with this design.

Thanks

[TDK]

One way would be to feed a clock signal to both using an XO. Another would be to generate the clock from one to send to the other using a TIM or MCO output.

[baselimadt]

Hi thanks for your answer
would you recommend a clock generator to feed them both, or a design document to help.

[Andrew Neil]

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@baselimadt wrote:

both MCUs to be run on the same time "same clock", to be synced together.

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Note that just running them on the same clock will not guarantee that they are synchronised!

See: https://community.st.com/t5/stm32-mcus-products/synchronizing-the-clocks-of-two-stm32s/m-p/719808/highlight/true#M261443

[baselimadt]

Hi 
I know this point, but for now I want to them to run on the same clock, since this is a requirement from the client.

[Andrew Neil · Accepted solution]

If you use a clock generator, then it's just a digital signal that you apply to both microcontrollers.

The microcontroller's datasheet will give the specifications of its input pin;

The clock generator's datasheet will give the specifications of its output pin.

Just make sure that those are compatible.

                               +------+
                               |      |
+---------+           +------->+ MCU1 |
|         |           |        |      |
|  Clock  |           |        +------+
|   Gen   +---------->+
|         |           |        +------+
+---------+           |        |      |
                      +------->+ MCU2 |
                               |      |
                               +------+

[baselimadt]

also could you suggest how to make sure that both MCUs are synced ?

[Andrew Neil]

You would need some protocol between them - hardware and/or software.

[baselimadt]

OK so I am adding a 25Mhz Oscillator with clock buffer to provide the generated clock for both MCUs
clock : https://www.mouser.co.il/ProductDetail/ECS/ECS-2520MV-250-CN-TR?qs=fAHHVMwC%252BbiTva9uv8VI%2Fw%3D%3D

Buffer: https://www.mouser.com/ProductDetail/Texas-Instruments/CDCLVC1102PWR?qs=CLImetaeaXWKcbklvvP3ww%3D%3D