EM78P259N/260N

8-Bit Microprocessor with OTP ROM

6.8Infrared Remote Control Application/PWM Waveform Generation

6.8.1 Overview

This LSI can easily output infrared carrier or PWM standard waveform. As illustrated below, the IR and PWM waveform generation function include an 8-bit down count timer/counter, high time, low time, and IR control register. The IROUT pin waveform is determined by IOCA0 (IR and TCCC scale control register), IOCB1 (high time rate, low time rate control register), IOC81 (TCCC counter), IOCA1 (high time register), and IOC91 (low time register).

FT:CLK(Fosc)

 

 

 

 

 

 

 

8 Bit counter

8 Bit counter

 

8 Bit counter

 

 

 

 

 

 

Scale

 

 

 

Scale

Scale

(IOCB1)

8-to-1 MUX

8-to-1 MUX

(IOCB1)

(IOCA0)

 

 

8-to-1 MUX

 

 

 

 

 

 

8

 

8bit binary

8bit binary

8

Auto-reload buffer

 

Auto-reload buffer

(High-time)(IOCA1)

down counter

down counter

(Low-time)(IOC91)

 

Fcarrier

 

8

8

 

 

 

 

 

 

 

 

 

 

8bit binary

 

 

 

 

 

down counter

 

 

H/W Modulator

 

8

 

 

 

 

 

Auto-reload buffer

HF

LGP

IRE

IROUT

Underflow Interrupt

(TCCC)(IOC81)

 

HPWTIF

 

 

 

 

 

 

 

pin

LPWTIF

Fig. 6-11 IR/PWM System Block Diagram

NOTE

Details of the Fcarrier high time width and low time width are explained below:

Fcarrier =

FT/ 2 { [1+decimal TCCC Counter value (IOC81)] * TCCC

 

Scale (IOCA0) }

High time width =

{ [1+decimal high time value (IOCA1)] * High time Scale

 

(IOCB1) } / FT

Low time width =

{ [1+decimal low time value (IOC91)] * Low time Scale

 

(IOCB1) } / FT

Where FT is the system clock

FT=Fosc/1 (CLK=2)

 

 

FT=Fosc/2 (CLK=4)

 

 

 

Product Specification (V1.2) 05.18.2007

• 51

(This specification is subject to change without further notice)

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IBM EM78P259N/260N manual Infrared Remote Control Application/PWM Waveform Generation, Overview