Fujitsu FR81S User Manual
CHAPTER 27: UP/DOWN COUNTER
6. Operation and Setting Procedure Examples
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : UP/DOWN COUNTER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
FUJITSU SEMICONDUCTOR CONFIDENTIAL
23
Clear Events
The counter value is cleared to "0000
H
" in one of the following events.
· This device is reset.
· An effective edge is entered from the ZIN pin.
· An effective edge is entered from the ZIN pin.
(If the CGSC bit of the counter control register (CCR) is set to make the ZIN pin work for the counter
clear function (CGSC=0).)
clear function (CGSC=0).)
· Software-triggered clear
The UDCC bit of the counter control register (CCR) is written to "0".
· Clear due to the compare function
The counter value matches the value set in the reload compare register (RCR) and an attempt is made to
increment the counter.
increment the counter.
(The counter is not cleared if an attempt is made to decrement or stop the counter.)
· Clear due to overflow
Count up/down timing after the counter reaches "FFFF
H
" (or "FF
H
" in 8-bit mode).
The time the counter is cleared to "0000
H
" depends on the up/down counter operating status as follows.
· If a clear event occurs during counting, the counter will be cleared in synchronization with the count
clock.
Figure 6-2 shows clear event occurrence timing.
Figure 6-2 Clear Event Occurrence Timing
· If a clear event occurs during counting and the counting stops before the next count clock pulse is entered
(the CSTR bit of the counter status register (CSR) is "0"), the value will be cleared when the up/down
counter stops.
Figure 6-2 shows the clear event occurrence timing.
counter stops.
Figure 6-2 shows the clear event occurrence timing.
UDCR
Clear event
Count clock
UDCR : Up/down count register
Synchronized with this clock pulse
0065
H
0066
H
0000
H
0001
H
MB91520 Series
MN705-00010-1v0-E
1030