UPD784938 Datasheet, PDF (278/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 10 TIMER/EVENT COUNTER 1
(2) Prescaler mode register 1 (PRM1)
In PRM1, the count clock to timer/event counter 1 TM1/TM1W is specified by the low-order 4 bits (the high-order 4 bits
specify the count clock to timer/event counter 2 TM2/TM2W).
PRM1 can be read or written to with an 8-bit manipulation instruction. The format of PRM1 is shown in Figure 10-3.
RESET input sets PRM1 to 11H.
Figure 10-3. Prescaler Mode Register 1 (PRM1) Format
7
6
5
4
3
2
1
0 Address After reset R/W
PRM1 PRS23 PRS22 PRS21 PRS20 PRS13 PRS12 PRS11 PRS10 0FF5EH 11H R/W
(fXX = 12.58 MHz)
PRS13 PRS12 PRS11 PRS10 Timer/Event Counter 1 (TM1/
TM1W) Count Clock Specification
Count Clock [Hz]
Specification
Resolution
[ µs]
0
0
0
0 Setting prohibited
–
0
0
0
1 fXX/4
0.64
0
0
1
0 fXX/8
1.27
0
0
1
1 fXX/16
2.54
0
1
0
0 fXX/32
5.09
0
1
0
1 fXX/64
10.17
0
1
1
0 fXX/128
20.35
0
1
1
1 fXX/256
40.70
1
0
0
0 fXX/512
81.40
1
0
0
1 fXX/1,024
162.80
1
1
1
1 External clock (INTP0)
–
Other than the above
Setting prohibited
Specifies count clock to TM2/TM2W of timer/event counter 2
(see Figure 11-3).
Remark fXX: X1 input frequency or oscillation frequency
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Preliminary User’s Manual U13987EJ1V0UM00