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CHAPTER 8 TIMER/COUNTER FUNCTION
270
User’s Manual U15109EJ3V0UD
(7) Prescaler mode registers 90, 91, 110, 111 (PRM90, PRM91, PRM110, PRM111)
PRM1n selects the count clock of the 16-bit timer (TM9, TM11) and the valid edge of the TIn0 and TIn1 inputs.
PRMn0 and PRMn1 are set by an 8-bit memory manipulation instruction (n = 9, 11).
RESET input clears PRMn0 and PRMn1 to 00H.
After reset: 00H R/W
Address: FFFFF3BEH, FFFFF0EEH
7
6
5
4
3
2
1
0
PRMn1
0
0
0
0
0
0
0
PRMn2
(n = 9, 11)
After reset: 00H R/W
Address: FFFFF3B6H, FFFFF0E6H
7
6
5
4
3
2
1
0
PRMn0
ESn11
ESn10
ESn01
ESn00
0
0
PRMn1
PRMn0
(n = 9, 11)
ESn11
ESn10
Selects valid edge of TIn1
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
ESn01
ESn00
Selects valid edge of TIn0
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
Count clock selection
f
PRMn2
PRMn1
PRMn0
Count clock
20 MHz
18.87 MHz
16 MHz
0
0
0
f
/4
200 ns
212 ns
250 ns
0
0
1
f
/8
400 ns
424 ns
500 ns
0
1
0
f
/32
1.6
µ
s
1.7
µ
s
2
µ
s
0
1
1
TIn0 valid edge
490
−
−
−
1
0
0
f
/64
3.2
µ
s
3.4
µ
s
4
µ
s
1
0
1
f
/128
6.4
µ
s
6.8
µ
s
8
µ
s
1
1
0
f
/512
25.6
µ
s
27.1
µ
s
32
µ
s
1
1
1
Setting prohibited
−
−
−
Note
A pulse longer than twice the internal clock (f
/2) is required for an external clock.