4570 Datasheet, PDF (20/69 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
4570 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
TIMERS
The 4570 Group has the programmable timers and a fixed
dividing frequency timer.
q Programmable timer
The programmable timer has a reload register and enables
the frequency dividing ratio to be set. It is decremented from a
set value n. When it underflows (count to n + 1), a timer interrupt
request flag is set to “1,” new data is loaded from the reload
register, and count continues (auto-reload function).
q Fixed dividing frequency timer
The fixed dividing frequency timer has the fixed frequency
dividing ratio (n). An interrupt request flag is set to “1” every n
count of a count pulse.
FF16
n : Counter initial value
Count starts
Reload
n
1st underflow
Reload
2nd underflow
0016
Timer 1 interrupt “1”
request flag
“0”
Fig. 18 Auto-reload function
n+1 count
n+1 count
Time
An interrupt occurs or
a skip instruction is executed.
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