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AN1602

APPLICATION NOTE

16-BIT TIMING OPERATIONS USING ST7262 OR ST7263B

MCUs

Microcontroller Division Applications

INTRODUCTION

This Application Note describes how to use the ST7262 or ST7263B for 16-bit timing opera-

tions. The intention of this document is to show how to perform pulse measurement and PWM

generation using the different timers available on each microcontroller type.

1 16-BIT TIMING MEASUREMENTS

1.1 USING ST7262

The aim of this section is to describe how to use the ST7262 8-bit timer to perform pulse and

frequency measurements with 16-bit accuracy.

1.1.1 16-Bit Capture

1.1.1.1 Principle

The ST7262 architecture allows you to cascade the 8-bit Auto Reload Timer (ART) with the 8-

bit Time Base Unit (TBU) to obtain a 16-bit counter (The carry bit of the ART acts as the clock

for the TBU). Using this configuration, the ARTCAR register represents the Least Significant

Byte and the TBUCV register represents the Most Significant Byte (see Figure 1).

Figure 1. TBU+ART 16-Bit Counter Value

On each valid input capture, the 16-bit counter value is obtained by:

– The ARTCAR register which is automatically latched.

– The TBUCV register which is saved by software in the Input Capture Interrupt routine.

This method ensures a “real-time” capture of the low bits, while the software delay needed to

save the TBUCV can be compensated.

16 Bit Counter Value

TBU (MSB)

ART (LSB)

1