UPD784938 Datasheet, PDF (222/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 9 TIMER/EVENT COUNTER 0
(2) Prescaler mode register 0 (PRM0)
The count clock of the timer/event counter 0 TM0 is specified by the low-order 4 bits of PRM0 (the high-order 4 bits specify
the count clock of the timer 3, TM3/TM3W).
PRM0 can be read/written with an 8-bit manipulation instruction. The format of PRM0 is shown in Figure 9-3.
RESET input sets PRM0 to 11H.
Figure 9-3. Prescaler Mode Register 0 (PRM0) Format
7
6
5
4
3
2
1
0 Address After reset R/W
PRM0 PRS3 PRS2 PRS1 PRS0 PRS03 PRS02 PRS01 PRS00 0FF5CH 11H R/W
(fXX = 12.58 MHz)
PRS03 PRS02 PRS01 PRS00 Timer/Event Counter 0 TM0 Count
Clock Specification
Count Clock [Hz]
Specification
Resolution
[ µs]
0
0
0
0 Setting prohibited
–
0
0
0
1 fXX/4
0.32
0
0
1
0 fXX/8
0.64
0
0
1
1 fXX/16
1.27
0
1
0
0 fXX/32
2.54
0
1
0
1 fXX/64
5.09
0
1
1
0 fXX/128
10.17
0
1
1
1 fXX/256
20.35
1
0
0
0 fXX/512
40.70
1
0
0
1 fXX/1,024
81.40
1
1
1
1 External clock (INTP3)
–
Other than the above
Setting prohibited
Specifies count clock of the TM3/TM3W of the timer 3
(see Figure 12-3).
Remark fXX: X1 input frequency or oscillation frequency
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Preliminary User’s Manual U13987EJ1V0UM00