Spi clocks are 4, 5, 6 instead of 8 bits

[dorong]

Hi all
I am using the stm32h743 device when using spi 6 to transmit data the clocks
are 4, 5, 6 randomly instead of 8 bits
when configuring spi2 the processor function perfectly.
on this device I have already used 
connection: SPI1, SPI5, ethernet, uart4.uart7,uart8, usart1,usart2,usart3
middleware and software package: freertos, LWIP
Timers: Timer1
System core: DMA, GPIO,NVIC, RCC, SYS
CubeMx Version 6.13
CubeIDE 1.16.0
Repository: 1.12.0

Thank you for you answer

[dorong]

I have checked all 6 SPI to be  configured as transmits master only 8 bit frame prescaler 256
only spi 6 behave sending 4 or 5 or 6 clocks instead of 8

[dorong]

Solution : if spi 6 clock is located on pa5 then this error will happen
relocate spi 6 clock to other pin and the problem mention before we be removed 
 

[Andrew Neil]

If the "problem" only happens on one particular pin, that's probably due to a conflict on the board ...

You haven't said what board you're using.

Check your schematics. If it's a custom board, also check for manufacturing faults/errors; eg, shorts.

Maybe get a logic analyser trace which shows SPI6 working (clock on a pin other than PA5), plus what's happening on PA5 - so a total of 5 signals: NSS, SCK, MOSI, MISO, PA5.

[dorong]

I am using stm32h743 evaluation board the pin are only connected to the logic analyzer
the board was replaced, to see if the problem was on a particular board.
i am in master transmit only mode only clock and mosi (data) pins are used.

[Andrew Neil]

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@dorong wrote:

I am using stm32h743 evaluation board .

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Which one, exactly?

This: https://www.st.com/en/evaluation-tools/stm32h743i-eval.html ?

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@dorong wrote:

i am in master transmit only mode only clock and mosi (data) pins are used.

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So just look at SCK, MOSI, and PA5.

[Andrew Neil]

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@Andrew Neil wrote:

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This: https://www.st.com/en/evaluation-tools/stm32h743i-eval.html ?

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If so, did you remove R118?

https://www.st.com/resource/en/user_manual/um2198-evaluation-boards-with-stm32h743xi-and-stm32h753xi-mcus-stmicroelectronics.pdf#page=25

also on the schematics:

[dorong]

stm32h743i-eval2

[Andrew Neil · Accepted solution]

So that is one covered by the Manual I linked:

So, again, did you remove R118 ?

If not, that explains why you couldn't use PA5!