Fujitsu FR81S User Manual
CHAPTER 27: UP/DOWN COUNTER
4. Registers
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : UP/DOWN COUNTER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
FUJITSU SEMICONDUCTOR CONFIDENTIAL
18
[bit2] UDFF : Underflow detection flag bit
This bit indicates that the up/down counter has underfollowed.
When this bit is "1" and the UDIE bit is set to "1", an underflow interrupt request is generated.
When this bit is "1" and the UDIE bit is set to "1", an underflow interrupt request is generated.
UDFF
Read
Write
0
No underflow has occurred.
This bit is cleared to "0".
1
An underflow has occurred.
Ignored
An underflow occurs if counting down is attempted when the counter value is "0000
H
".
[bit1, bit0] UDF1, UDF0 : Up/down flag bits
These bits indicate the last counting direction.
These bits are updated every time the up/down counter counts.
These bits are updated every time the up/down counter counts.
UDF1
UDF0
Description
0
0
No input
0
1
Count down
1
0
Count up
1
1
Count up/count down at the same time
MB91520 Series
MN705-00010-1v0-E
1025