STM32U5 with DMA request AND trigger.

[jeffl.kelley9]

I have GPDMA working on STM32U5 with a circular buffer.  However, when I add a GPDMA "trigger" to the setup, the DMA no longer works.

GPDMA1_C2TR2.TRIGPOL=2

GPDMA1_C2TR2.TRIGSEL=11

GPDMA1_C2TR2.TRIGM=3

LPTIM1 setup to clock away at a 50% duty cycle.

What I would expect to see is the DMA transfer working slower than normal based on the ARR period of LPTIM1.  But, the above combination of values along with a few variations just results in stopping the DMA.

What would be helpful is some example application running on a nucleo board which makes use of a GPDMA driven device where both a DMA request and a DMA trigger are being used.  (Documentation seems to be lacking.  They do describe what the triggers are and from what I can tell how they should work, but because it is not working some vital clue is missing or hidden.)

[Khaled_DHIF]

Hello @jeffl.kelley9 ,

Thank you for providing information about your GPDMA and LPTIM1 setup. The behavior you describe when enabling the DMA trigger suggests there might be a subtle configuration or synchronization issue. To assist you further, could you please share the full register dump or additional context from your application when the issue occurs? This will help in diagnosing the root cause more precisely.

In the meantime, I recommend reviewing the DMA_Trigger example available in the STM32CubeU5 firmware package for the STM32U575I-EV board, which demonstrates the use of GPDMA with triggers. This example might provide useful insights or clues to resolve the problem.