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(3) Prescaler mode register (PRM0)
This register is used to set 16-bit timer (TM0) count clock and valid edge of TI0n (n = 0 to 2) input.
PRM0 is set with an 8-bit memory manipulation instruction.
RESET input sets PRM0 value to 00H.
Address: FF70H
After Reset: 00H
Symbol
7
PRM0
ES21
ES21
0
0
1
1
ES11
0
0
1
1
ES01
0
0
1
1
PRM01
0
0
1
1
Caution
Timer operation must be stopped before setting PRM0.
CHAPTER 7 16-BIT TIMER 0 TM0
Figure 7-4. Prescaler Mode Register (PRM0) Format
R/W
6
5
4
ES20
ES11
ES10
ES20
0
Falling edge
1
Rising edge
0
Setting prohibited
1
Both falling and rising edges
ES10
0
Falling edge
1
Rising edge
0
Setting prohibited
1
Both falling and rising edges
ES00
0
Falling edge
1
Rising edge
0
Setting prohibited
1
Both falling and rising edges
PRM00
3
0
f
/2
X
4
1
f
/2
X
5
0
f
/2
X
6
1
f
/2
X
3
2
ES01
ES00
PRM01
TI02 Valid Edge Selection
TI01 Valid Edge Selection
TI00 Valid Edge Selection
Count Clock Selection
1
0
PRM00
105
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