MITSUBISHI MICROCOMPUTERS
4551 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for
INFRARED REMOTE CONTROL TRANSMITTER
Timer 1 “1”
underflow “0”
Timer 1 start
Port CARR “H”
output
“L”
(C20)←1
a
b
c
d
v
v
Set the interval Set the interval “b” to
“a” to timer 1. reload register R1.
v
Set the interval “c” to
reload register R1.
v
Set the interval “d” to
reload register R1.
Carrier wave output start
Timer 1 underflow
“1”
“0”
Port CARR output
“H”
“L”
“1”
Register C20 “0”
Carrier wave output start
v
(C20)←0
v
v
v
(C20)←1 (C20)←0 (C20)←1
Fig. 23 Carrier wave output auto-control by timer 1
25