MITSUBISHI MICROCOMPUTERS
4280 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS
The 4280 Group timer consists of the following circuit.
• Timer 1 : 8-bit programmable timer
This timer can be controlled with the timer control register V1.
Timer 1 function is described below.
Table 3 Function related timer
Control
register
V1
Frequency
Circuit
Timer 1
Use of output signal
Structure
Count source
dividing ratio
8-bit programmable
binary down counter
• Carrier generating circuit 1 to 256
output (CARRY)
• Carrier wave output control
• Bit 5 of watchdog timer
SNZT1 instruction
V10
(Note 1)
V1
1
0
1
0
Timer 1 (8)
CARRY
T1F
1
Q
R
D
T
Carrier wave output control signal
Reload register R1 (8)
(Note 2)
(T1AB)
V10
V12
(TAB1)
Register B
Register A
STCK (System clock)
Frequency
divider
(divided by 8)
Frequency
divider
INSTCK
(Instruction clock)
(divided by 4)
XIN
Synchronous
circuit
CCK instruction
S
R
Q
Initializing signal
(Note 3)
(Note 3)
Initializing signal
System reset
14-bit timer (WDT)
13
WDF1 WDF2
INSTCK
0
5
WRST instruction
Initializing signal
(Note 3)
Notes 1: Counting is stopped by clearing to “0.”
2: When the T1AB instruction is executed after V1
writing is performed only to reload register R1.
0
is set to “1,”
3: The initializing signal is output at reset or RAM back-up mode.
: Data is automatically set from a reload register
when timer 1 underflows (auto-reload function).
Fig. 13 Timers structure
MITSUBISHI
ELECTRIC
11
MITSUBISHI [ Mitsubishi Group ]
