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Raees
Raees
Associate II
July 10, 2020
Question

STM32H750 GPIO slow compared to STM32F2 series

  • July 10, 2020
  • 3 replies
  • 1340 views

Driving a RGB led matrix display (HUB75E) using custom board made with STM32H750. Earlier the prototype was made with STM32F205 and there was a minute flickering in some scenarios (brightness low). so thought of designing the board with STM32H7. But in STM32H7 the flickering is higher than STM32F2 (way higher). No other processing is happening in this testing.

what is the maximum GPIO switching frequency in STM32H7? does H7 series have any drawback in GPIO performance (even though it have the highest cpu clock)

CPU is clocked with HSE 480MHz (25MHz external crystal)

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    3 replies

    TDK
    TDK
    July 10, 2020

    Max switching frequency of GPIO per the datasheet is 220 MHz. Better than the F2.

    But if it's visibly flickering, seems like that would be taking place at a much much lower frequency than what the GPIO pins are capable of, even in the slowest speed setting.

    "If you feel a post has answered your question, please click ""Accept as Solution""."
    Nikita91
    Nikita91
    Lead II
    July 11, 2020

    The H7 has a much more complex architecture: There are more buses and therefore more bridges.

    The H7 clock is faster, but GPIO access is slower because of the number of bridges to cross ...

    Pavel A.
    Pavel A.
    July 11, 2020

    What is flickering? Have you looked at the signal with a suitable instrument? Maybe the switching frequency is not the issue here at all.

    -- pa

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