AN590/0703

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AN590

APPLICATION NOTE

PWM GENERATION WITH ST62 AUTO-RELOAD TIMER

by Microcontroller Division Applications

INTRODUCTION

This note describes how to use the ST62 Auto-reload Timer (ARTimer) to generate a PWM

signal with tunable frequency and duty cycle. As an example, the generation of a 31.25kHz

PWM signal with duty cycle proportional to an analog input voltage is presented.

Auto-reload Timer description

This timer is an 8 bit timer/counter with prescaler. It includes auto-reload PWM, capture and

compare capability with one input and one output pin. It is controlled by the following registers

(8 bit):

– Mode Control Register (MC)

– Status registers (SC0, SC1)

– Load register (LR)

– Incremental counter register (TC)

– Compare register (CP)

– Reload/Capture register (RC)

It can also wake up the MCU from wait mode and exit from stop mode if an external event is

present on the input pin. The prescaler ratio can be programmed to choose the timer input fre-

Figure 1. Auto-reload Timer Block Diagram

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