
S1C88409 TECHNICAL MANUAL
EPSON
63
CHAPTER 5: PERIPHERAL CIRCUITS AND OPERATION (Prescaler and Clock Control Circuit)
5.5.5 I/O memory of prescaler
Table 5.5.5.1 shows the control bits for the prescaler.
Table 5.5.5.1(a) Prescaler control bits
Address
Function
R/W
Init
0
1
Comment
Name
Bit
00FF01
–
Wait state control
CPU operating clock switch
OSC3 oscillation ON/OFF control
VD1 output level setting
–
R/W
–
0
–
OSC1
Off
–
OSC3
On
"0" when being read
–
WT1
WT0
CLKCHG
OSCC
VD1C1
VD1C0
D7
D6
D5
D4
D3
D2
D1
D0
WT1
1
0
WT0
1
0
1
0
Number of states
12(3 cycles)
8(2 cycles)
4(1 cycles)
No wait
VD1C1
1
0
VD1C0
1
0
1
0
VD1(Typ.)
4.2 V
3.2 V
1.6 V
2.4 V
00FF10
16-bit programmable timer 1 clock control
16-bit programmable timer 1 division ratio
16-bit programmable timer 0 clock control
16-bit programmable timer 0 division ratio
R/W
0
Off
On
PRPRT1
PST12
PST11
PST10
PRPRT0
PST02
PST01
PST00
D7
D6
D5
D4
D3
D2
D1
D0
PST12
1
0
PST11
1
0
1
0
PST10
1
0
1
0
1
0
1
0
(OSC3)
fOSC3 / 4096
fOSC3 / 1024
fOSC3 / 256
fOSC3 / 128
fOSC3 / 64
fOSC3 / 32
fOSC3 / 8
fOSC3 / 2
(OSC1)
fOSC1 / 128
fOSC1 / 64
fOSC1 / 32
fOSC1 / 16
fOSC1 / 8
fOSC1 / 4
fOSC1 / 2
fOSC1 / 1
PST02
1
0
PST01
1
0
1
0
PST00
1
0
1
0
1
0
1
0
(OSC3)
fOSC3 / 4096
fOSC3 / 1024
fOSC3 / 256
fOSC3 / 128
fOSC3 / 64
fOSC3 / 32
fOSC3 / 8
fOSC3 / 2
(OSC1)
fOSC1 / 128
fOSC1 / 64
fOSC1 / 32
fOSC1 / 16
fOSC1 / 8
fOSC1 / 4
fOSC1 / 2
fOSC1 / 1
00FF11
–
8-bit programmable timer clock control
8-bit programmable timer division ratio
–
R/W
–
0
–
Off
–
On
"0" when being read
–
PRPRT2
PST22
PST21
PST20
D7
D6
D5
D4
D3
D2
D1
D0
PST22
1
0
PST21
1
0
1
0
PST20
1
0
1
0
1
0
1
0
Division ratio
fOSC3 / 256
fOSC3 / 128
fOSC3 / 64
fOSC3 / 32
fOSC3 / 16
fOSC3 / 8
fOSC3 / 4
fOSC3 / 2
00FF12
–
16-bit programmable timer 1 source clock selection
16-bit programmable timer 0 source clock selection
–
R/W
–
0
–
fOSC3
–
fOSC1
"0" when being read
–
PRTF1
PRTF0
D7
D6
D5
D4
D3
D2
D1
D0