5 replies

Managing DMA Callback and FreeRTOS Tasks with Timing Constraints on STM32f4

My current project involves constantly receiving digital samples through DMA on an STM32f4 and performing DSP in the complete callback interrupt triggered after each sample. However, frequent callbacks are hindering freeRTOS from running other tasks while DMA waits for completion. My objective is to allow freeRTOS tasks to run every 6ms following a completed DMA callback.

Initially, I thought about disabling interrupts using

__disable_irq()

__disable_irq()

in the complete callback and re-enabling them with

__enable_irq()

__enable_irq()

, but considering my high-priority button interrupt was still active—and not knowing whether this technique could guarantee exactly 6ms—I tried another approach of only deactivating the specific DMA interrupt by utilizing

__set_BASEPRI(priority << (8 - __NVIC_PRIO_BITS))

__set_BASEPRI(priority << (8 - __NVIC_PRIO_BITS))

.
I then started a timer that runs at intervals of 6ms before restoring normal function via calling back with

_ _set_BASEPRI(0)

_ _set_BASEPRI(0)

upon elapsed period time completing successfully executed timed actions—nonetheless,it did not work since it kept switching between both types of call-backs without allowing freertos tum to operate independently.

I would greatly appreciate any feedback or advice. Thanks

Solution

Adjusting the timing might help yeah , but it's more about ensuring the callbacks don’t hog all the CPU time. By using double buffering or adjusting interrupt priorities, you’re already reducing the time DMA interrupts take. If FreeRTOS still isn’t getting enough time, you might also consider tweaking task priorities or adding some delay within the callback if possible…

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DIIS

DevHeads IoT Integration Server•2y ago•

5 replies

Sterling

Managing DMA Callback and FreeRTOS Tasks with Timing Constraints on STM32f4

__disable_irq()

__disable_irq()

in the complete callback and re-enabling them with

__enable_irq()

__enable_irq()

__set_BASEPRI(priority << (8 - __NVIC_PRIO_BITS))

__set_BASEPRI(priority << (8 - __NVIC_PRIO_BITS))

.
I then started a timer that runs at intervals of 6ms before restoring normal function via calling back with

_ _set_BASEPRI(0)

_ _set_BASEPRI(0)

Solution

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Managing DMA Callback and FreeRTOS Tasks with Timing Constraints on STM32f4

Managing DMA Callback and FreeRTOS Tasks with Timing Constraints on STM32f4

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