CHAPTER 8 TIMER/COUNTER FUNCTION
264
User’s Manual U15109EJ3V0UD
(4) Prescaler mode registers 00, 01 (PRM00, PRM01)
PRM0n selects the count clock of the 16-bit timer (TM0) and the valid edges of the TI00 and TI01 inputs. PRM00
and PRM01 are set by an 8-bit memory manipulation instruction.
RESET input clears PRM00 and PRM01 to 00H.
After reset: 00H R/W
Address: FFFFF20EH
7
6
5
4
3
2
1
0
PRM01
0
0
0
0
0
0
0
PRM02
After reset: 00H R/W
Address: FFFFF206H
7
6
5
4
3
2
1
0
PRM00
ES011
ES010
ES001
ES000
0
0
PRM01
PRM00
ES011
ES010
Selects valid edge of TI01
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
ES001
ES000
Selects valid edge of TI00
0
0
Falling edge
0
1
Rising edge
1
0
Setting prohibited
1
1
Both rising and falling edges
Count clock selection
f
PRM02
PRM01
PRM00
Count clock
20 MHz
18.87 MHz
16 MHz
0
0
0
f
/2
100 ns
0.5 ns
125 ns
0
0
1
f
/16
800 ns
848
µ
s
1
µ
s
0
1
0
INTWTNI
−
−
−
0
1
1
TI00 valid edge
490
−
−
−
1
0
0
f
/4
200 ns
212 ns
250 ns
1
0
1
f
/64
3.2
µ
s
3.4
µ
s
4
µ
s
1
1
0
f
/256
12.8
µ
s
13.6
µ
s
16
µ
s
1
1
1
Setting prohibited
−
−
−
Note
A pulse longer than twice the internal clock (f
/2) is required for an external clock.