Z86L88 Datasheet, PDF (38/66 Pages) Zilog, Inc. – INFRARED REMOTE CONTROLLERS

Z86L88/81/86/87/89/73
IR/Low-Voltage Microcontroller
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 28).
T8 (8-Bit)
Count Capture
T8_Enable
(Set By User)
No
Yes
Edge Present
No
Yes
Pos
T8 → L08
What Kind Of Edge
Neg
T8 → HI8
%FF → T8
Figure 28. Demodulation Mode Count Capture Flowchart
38
PRELIMINARY
DS96LV00800