Fujitsu F2MC-16LX Hardware Manual page 277

[Bit 4] CMPF (compare detect flag)
This bit is a flag indicating that the UDCR and RCR values match each other after a
comparison.
Only writing "0" is permitted, and "1" cannot be written.
Read-modify-write type instructions return "1" irrespective of bit values.
CMPF
0 No match in compare results (initial value)
1 Match in compare results
[Bit 3] OVFF (overflow detect flag)
This bit is a flag indicating an overflow occurred.
Only writing "0" is permitted, and "1" cannot be written.
Read-modify-write type instructions return "1" irrespective of bit values.
OVFF
0 No overflow occurred (initial value)
1 Overflow occurred
[Bit 2] UDFF (underflow detect flag)
This bit is a flag indicating that an underflow occurs.
Writing "0" is only permitted but not writing "1".
Read-modify-write type instructions return "1" irrespective of bit values.
UDFF
0 No underflow occurred (initial value)
1 Underflow occurred
[Bits 1 to 0] UDF1, UDF0 (up/down flag)
These bits are used to indicate the last count operation (up/down) performed.
Only reading is permitted but writing is not.
UDF1 UDF0
0 0
0 1
1 0
1 1
CHAPTER 13 8/16-BIT UP/DOWN COUNTER/TIMER
Match/no match at compare detection
Overflow occurrence
Underflow occurrence
No input (initial value)
Decremented
Incremented
Simultaneous up/down occurred
Detect edge
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