Universal Remote Control R7 - SPECS SHEET Manual de usuario descargar pdf (Pagina 9)

IR REMOTE CONTROLLER S3F80KB_AN_REV 0.00 (Preliminary Spec)

2.5 TRANSMISSION MODE

2.5.1 Counter A

26.4us

CDATAL CDATAH

1/3 duty

Figure 3. Carrier Frequency

Counter A is used to trasmit carrier frequency and supply a clock source to the Timer 1.

To make tLOW = 8.8 us and tHIGH = 17.6 us. fOSC = FX =8 MHz

[Method 1] When CAOF = 0,

tLOW = 8.8 us = (CADATAL + 2) / FX = (CADATAL + 2) x 125ns, CADATAL = 33.

tHIGH = 17.6 us = (CADATAH + 2) / FX = (CADATAH + 2) x 125ns, CADATAH = 68.

This is the example of counter A to generate a carrier frequency. CADATAL generates 17.5us low pulse.

CADATAH generates 8.7us high pulse. Port 3.1 is configured REM to transmit carrier frequency. CounterA

repeatedly countes CADATAH and CDATAL to transmit carrier frequency through P3.1. REM port can be

controlled by setting P3.7. If P3.7 is setted to 1, REM signal is transmited through P3.1. If P3.7 is setted to 0,

REM signal is not transmitted. But counterA doesn’t stop counting. If you want to stop counting a counterA, you

have to set CACON.2 to 1.

2.5.2 Timer 1

Timer 1 is used to generate the envelope pattern for the remote controller signal. Carrier frequency which is

generated by Counter A is used as Timer 1’s clock source by setting T1CON.7 to 1. Timer1 countes high and low

length of the leader, bit 0 and 1. When Timer1 counter reaches the T1DATAH and T1DATAL value, Timer1 match

interrupt is generated. Then IR signal is transmitted through P3.1(REM) that can be turned on or off by setting

P3.7 to 1 or 0. Timer 1 match interrupt pending condition is not automatically cleared in interval timer mode. The

T1INT pending condition must be cleared by application’s interrupt servie routine by writing a '1' to the T1CON.0

interrupt pending bit.

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Universal Remote Control R7 - SPECS SHEET Manual de usuario Pagina 9