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CHAPTER 13 8/16-BIT UP/DOWN COUNTER/TIMER
[bit4] CMPF (compare detect flag)
This bit is a flag indicating that the UDCR and RCR values match each other after a
comparison.
The initialization (writing "0") is only permitted.
Read-modify-write type instructions read "1" irrespective of bit values.
CMPF
0
1
[bit3] OVFF (overflow detect flag)
This bit is a flag indicating an overflow occurred.
The initialization (writing "0") is only permitted.
Read-modify-write type instructions read "1" irrespective of bit values.
OVFF
0
1
[bit2] UDFF (underflow detect flag)
This bit is a flag indicating that an underflow occurs.
The initialization (writing "0") is only permitted.
Read-modify-write type instructions read "1" irrespective of bit values.
UDFF
0
1
[bit1, bit0] 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
0
0
1
1
272
Match/no match at compare detection
No match in compare results (initial value)
Match in compare results
No overflow occurred (initial value)
Overflow occurred
No underflow occurred (initial value)
Underflow occurred
UDF0
0
No input (initial value)
1
Decremented
0
Incremented
1
Simultaneous up/down occurred
Overflow occurrence
Underflow occurrence
Detect edge
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