Dimming application using an STM32 microcontroller

AN2841

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3.1.4

Single interrupt with DMA

The data is transferred from the microcontroller RAM into the LED driver using a single

interrupt with DMA approach. You cannot use a DMA approach without a timer, because you

cannot change the speed of the DMA and thus you cannot change PWM parameters and

the refresh rate in required steps. The benefit of using DMA is that the SPI buffer can be

automatically filled. The time saved is nearly in the range of the time needed for the DMA to

restart and re-configure itself for the next transfer (in comparison to previous approach). An

example of a timing diagram for this programming model is shown in Figure 14. The timing

can be compared in Figure 12 and Figure 14.

Figure 14.

Timing diagram: Single interrupt with DMA