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Fan Out of single SPI interface in STM32F745IG


Hello Community!,
I am working on STM32F745IG, where i am interfacing 24 SPI slaves to STM32F745IG MCU. Please let me know how many slaves can be connected to single SPI interface in STM32F745IG?. I looked into datasheet, I couldn't able to find. 
Thank you.

David Littell
Senior III

With that many slaves I'd suggest that you really should mux/buffer every signal.  Capacitive loading alone will wreck the edge rates.  For any significant clock rate and/or trace distance I'd be very, very careful of signal integrity beyond about 4 or 5 slaves per F7 SPI.


This is limited by the board layout, not the STM32. If you are using slowish speeds (say 1 MHz or under) and have short traces from MCU to slave, 24 slaves should work be just fine.

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Buffers and line decoders,  could likely do it with much lower pin-count device.

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