
Rev.1.02
Nov 26, 2008
REJ03B0224-0102
455A Group
The 455A Group timer consists of the following circuits.
 Prescaler : 8-bit programmable timer
 Timer 1 : 8-bit programmable timer
 Timer 2 : 8-bit programmable timer
 Timer 3 : 16-bit fixed frequency timer
 Timer LC : 4-bit programmable timer
 Watchdog timer: 16-bit fixed frequency timer
(Timers 1, 2 and 3 have the interrupt function, respectively)
Prescaler, timer 1, timer 2, timer 3 and timer LC can be
controlled with the timer control registers PA and W1 to W5. The
watchdog timer is a free counter which is not controlled with the
control register.
Each function is described below.
Table 16 Function related timers
Circuit
Structure
Count source
Frequency
dividing ratio
Use of output signal
Control
register
Prescaler
8-bit programmable
binary down counter
 Instruction clock (INSTCK)
1 to 256
 Timer 1 count source
 Timer 2 count source
 Timer 3 count source
PA
Timer 1
8-bit programmable
binary down counter
(link to INT input)
(carrier wave output auto-
control function)
 PWM signal (PWMOUT)
 Prescaler output (ORCLK)
 Timer 3 underflow (T3UDF)
 CNTR input
1 to 256
 CNTR output control
 Timer 1 interrupt
W1
W4
Timer 2
8-bit programmable
binary down counter
(with carrier wave
generation function)
XIN input
 Prescaler output divided by 2
(ORCLK/2)
1 to 256
 Timer 1 count source
 CNTR output
 Timer 2 interrupt
W2
W4
Timer 3
16-bit fixed dividing
frequency
XCIN input
 Prescaler output (ORCLK)
 High-speed on-chip oscillator
(f(HSOCO))
 Low-speed on-chip oscillator
(f(LSOCO))
512
1024
2048
4096
8192
16384
32768
65536
 Timer 1 count source
 Timer LC count source
 Timer 3 interrupt
W3
W5
Timer LC
4-bit programmable binary
down counter
 Bit 4 of timer 3 (T34)
 System clock (STCK)
1 to 16
 LCD clock
W4
Watchdog
timer
16-bit fixed dividing
frequency
 Instruction clock (INSTCK)
65536
 System reset (counting twice)
 Decision of flag WDF1
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