HAL_SAI_Receive_DMA doesn't start the DMA

[ELaha]

Platform: STM32WB55 discovery board connected to I2S codec.

My mission: To receive data from the codec using DMA transfer.

Calling to HAL_SAI_Receive function returns the data correctly so I guess that everything is configured correctly.

When calling to HAL_SAI_Receive_DMA, hdma->Instance->CNDTR stays on the same initial value.

When debugging the code and running the HAL functions in single step - I do get the half full interrupt and the buffer contains the correct values. So again - I guess that everything is configured correctly.

The base code is generated with CubeMX.

HAL_SAI_Receive_DMA is called from the main loop, so I guess it is not related to interrupt priority issues.

Any other ideas?

Thanks!

[waclawek.jan]

Read out and check the SAI and DMA registers, including the DMA status register. Compare between working and not working case.

JW

[ELaha · Accepted solution]

Issue solved.

Due to high I2S clock frequency (~12Mhz), an AFSDET interrupt occurred and aborted the DMA transfer before it even started.

Reducing the clock frequency to ~2Mhz solved this issue.

I didn't check if 12Mhz clock should be supported when SAI1 clock mux is set to 48Mhz, but in fact - the HAL drivers behave differently.

Thanks.

[waclawek.jan]

Thanks for coming back with the solution.

I'm not sure why do you see AFSDET interrupt, as it should occur only in slave mode, but I don't know exactly what do you do and I'm definitively not going to investigate Cube/HAL's workings.

Please mark your post as "Best" so that the thread is marked as solved.

JW