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4583 Datasheet, PDF (29/153 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER | |||
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4583 Group
PRELIMINARY
Notice: This is not a final specification.
Some parametric limits are subject to change.
TIMERS
The 4583 Group has the following timers.
⢠Programmable timer
The programmable timer has a reload register and enables the
frequency dividing ratio to be set. It is decremented from a set-
ting value n. When it underflows (count to n + 1), a timer interrupt
request flag is set to â1,â new data is loaded from the reload reg-
ister, and count continues (auto-reload function).
⢠Fixed dividing frequency timer
The fixed dividing frequency timer has the fixed frequency divid-
ing ratio (n). An interrupt request flag is set to â1â after every n
count of a count pulse.
FF16
n : Counter initial value
Count starts
Reload
n
1st underflow
Reload
2nd underflow
0016
Timer interrupt â1â
request flag â0â
n+1 count
Fig. 24 Auto-reload function
The 4583 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 : 8-bit programmable timer
⢠Timer 4 : 8-bit programmable timer
⢠Watchdog timer : 16-bit fixed dividing frequency timer
(Timers 1, 2, 3, and 4 have the interrupt function, respectively)
Prescaler and timers 1, 2, 3, and 4 can be controlled with the timer
control registers PA, W1 to W6. The watchdog timer is a free
counter which is not controlled with the control register.
Each function is described below.
n+1 count
Time
An interrupt occurs or
a skip instruction is executed.
Rev.3.00 Aug 06, 2004 page 29 of 151
REJ03B0009-0300Z
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