Z86L71 datasheet(31/61 Pages) ZILOG

31 / 61 page

Z86L70/71/75/C71

Zilog

IR/Low-Voltage Microcontroller

DS97LVO0500

P R E L I M I N A R Y

1-31

T8 Demodulation Mode

The user should program TC8L and TC8H to %FF. After

T8 is enabled, when the first edge (rising, falling, or both

depending on CTR1 D5, D4) is detected, it starts to count

down. When a subsequent edge (rising, falling, or both de-

pending on CTR1 D5, D4) is detected during counting, the

current value of T8 is one's complemented and put into

one of the capture registers. If it is a positive edge, data is

put into LO8, if negative edge, HI8. One of the edge detect

status bits (CTR1 D1, D0) is set, and an interrupt can be

generated if enabled (CTR0 D2). Meanwhile, T8 is loaded

with %FF and starts counting again. Should T8 reach 0,

the time-out status bit (CTR0 D5) is set, an interrupt can be

generated if enabled (CTR0 D1), and T8 continues count-

ing from %FF (Figure 21).

Figure 21. Demodulation Mode Count Capture Flowchart

T8 (8-Bit)

Count Capture

T8_Enable

(Set By User)

Yes

Edge Present

Yes

What Kind Of Edge

Pos

→ L08

Neg

→ HI8

%FF

→ T8

Z86L71 Datasheet(PDF) 31 Page - Zilog, Inc.