Renesas 4514 - Manual (Page 42)

4513/4514 Group User’s Manual
HARDWARE
1-29
FUNCTION BLOCK OPERATIONS
TIMERS
The 4513/4514 Group has the programmable timers.
• Programmable timer
The programmable timer has a reload register and enables the
frequency dividing ratio to be set. It is decremented from a setting
value n. When it underflows (count to n + 1), a timer interrupt re-
quest flag is set to “1,” new data is loaded from the reload
register, 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 “1” after every n
count of a count pulse.
Fig. 18 Auto-reload function
FF 16
n
00 16
n : Counter initial value
Count starts Reload Reload
1st underflow 2nd underflow
n+1 count n+1 count
Time
An interrupt occurs or
a skip instruction is executed.
Timer interrupt
request flag
The contents of counter
“1”
“0”