AN2841

Dimming application using an STM32 microcontroller

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3.1.5

Interrupt + DMA + interrupt

Figure 14 shows that data from the previous transfer is latched during the current timer

interrupt which causes several problems. The algorithm is more complicated in this case.

A slightly different approach that has no impact on the system can be used: it is obtained by

generating the LE pulse when the DMA transfer is complete instead of generating it on

a timer interrupt. The LE pulse is generated at the DMA transfer complete interrupt as

shown in Figure 15.

Figure 15.

Timer interrupt + DMA transfer + DMA interrupt

Figure 16 shows the waveform of the outbound signals from the microcontrollers controlling

the LED drivers. An example of the C code implementation of the timer routine is given

below. A detailed description follows the example.