AN2841 datasheet(17/31 Pages) STMICROELECTRONICS

Teilenummer	AN2841

Bauteilbeschribung	This application note deals with the general principles of LED dimming

PDF	31 Pages

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Hersteller	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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17 / 31 page

AN2841

Dimming application using an STM32 microcontroller

17/31

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.

AN2841 Datenblatt(PDF) 17 Page - STMicroelectronics