Regarding SPI communication using DMA and manual SPI_CS operation

We are performing SPI communication using DMA.

In this case, we manually set the GPIO to High/Low as SPI_CS, but (obviously) SPI_CS goes High before all of the SPI CLK is sent.

How can we manually return SPI_CS to its original state after all of the SPI CLK has been sent?
Should We use SPI_DMATransmitReceiveCplt?

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Best answer by Saket_Om

Hello @pass3master

You need to set the SPI global interrupt in the .ioc.
In your code call HAL_SPI_TransmitReceive_DMA() and then set CS high in the HAL_SPI_TxRxCpltCallback().

Super User

@pass3master wrote:
we manually set the GPIO to High/Low as SPI_CS, but (obviously) SPI_CS goes High before all of the SPI CLK is sent.

No, that's not obvious at all - that's an error in your code!

When you choose to "manually" control CS, it's up to your code to ensure that it is asserted & released at the appropriate times.

@pass3master wrote:
Should We use SPI_DMATransmitReceiveCplt?

That would be the obvious way to do it - as the name suggests, that tells you when the transaction is complete!

Explorer

SPI_DMATransmitReceiveCplt is not called. Is there something we need to set? Do we need to set the ioc file?

Super User

Have you enabled the interrupt?

Super User

You should set CS high in HAL_SPI_TxRxCpltCallback.

If that's not working, show the relevant code. Ensure DMA interrupts are enabled.

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