STM32F4. Interrupt from DMA burst writing only once appears

[Alex Mach]

MCU is STM32F405. I write data array to output pins using DMA mem to peripheral (DM2 stream6 channel0). Trigger is TIM1 CC1 event. Also I use DMA2 stream5 channel6 for write to TIM1 registers. Trigger is TIM1 UEV event. So the writing and interrupt DMA_IT_TCIF5 appears ony once but TIM1_SR.UIF is set every time.

[waclawek.jan]

Is there any question?

JW

[Alex Mach]

My question is why only once the interrupt appears? Update events occurs but no DMA burst writing and no interrupts generates.

[waclawek.jan]

Why do you think several interrupt should appear? Do you set DMA as circular? Is there any DMA transfer error indicated in the DMA status register?

JW

[Tesla DeLorean]

Is the Stream 5 circular? TC will normally occur once per DMA transfer (could involve thousands of DMA requests), once the last work is delivered.

Check for error status from the DMA unit.

[Alex Mach]

There aren't any errors at DMA unit. DMA is normal, but UEV occurs periodically. So I think TC will occur for every UEV. It's not true?

[Tesla DeLorean]

TC will only fire once all available data is consumed​. It can keep firing only if the DMA is in circular mode, reseting the buffer pointer/size at completion of entire buffer. This can be at a rate significantly decimated compared to the TIM triggered requests.

[Alex Mach]

Thanks!

[Alex Mach]

Thanks!