Dimming application using an STM32 microcontroller

AN2841

10/31

The LED brightness value is defined by the user in the

LEDmap array. The LEDmap is an

array of 8-bit numbers (when using an 8-bit dimming resolution). Each value is dedicated

to one single LED (Figure 7).

The dimming algorithm converts the

LEDmap array into a serial stream. The serial stream

in combination with the LE signal generates requested PWM outputs on the LED drivers

as shown in Figure 8.

Figure 7.

Computation of

LEDdriverDATAbuffer variable

AM00346

depth = 0

DATAchar = 0

DATAchar++

Detail in Figure 8:

LEDmap

LEDdriverDATAbuffer

depth++

LED

Driver

SPI

0 .. 255 for 8-bit PWM resolution

0 .. LEDcount / 8

–

–

+

+

DATAchar>3

depth>255

Begin