SPI link max speed between two STM32 of different families

[sylvain2]

Posted on June 22, 2016 at 16:32

Hi all,

I have two boards which are respectively including an STM32F429 and an STM32F303.

I want to achieve a SPI link between those boards with these following features.

- STM32F429 is master; STM32F303 is slave

- STM32F303 is transmit only; so it never receives anything from the 429.

- Max SPI clock of 429 is 45Mhz

- Max SPI clock of 303 is 18MHz

Simple question:

Is it possible to transmit the data from the 303 to the 429 at 45MHz since the 303 receives its clock signal from the 429 ?

If yes, does it means that the SPI peripherals inside the MCU does not have any mechanism that implies the local clock of the MCU ? Also is it possible that a difference of fabrication tehchnology makes this SPI operation at 45MHz impossible beacause the 303 can not support it in terms of its limiting techno parameters ?

Thanks,

Sylvain

[Tesla DeLorean]

Posted on June 22, 2016 at 18:03

The SPI bus is limited by the APB clock the peripheral is attached to, and the synchronizer circuitry on the pin input(s) to get it into the clock domain. As such the input of 45 MHz signals seems highly improbable.

For high speeds your parts would probably want to share a common HSE source.