18 R/F CONVERTER (RFC)
18-8
Seiko Epson Corporation
S1C17M20/M21/M22/M23/M24/M25
TECHNICAL MANUAL (Rev. 1.0)
18.6 Control Registers
RFC Ch.
n
Clock Control Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
RFCnCLK
15–9 –
0x00
–
R
–
8
DBRUN
1
H0
R/W
7–6 –
0x0
–
R
5–4 CLKDIV[1:0]
0x0
H0
R/W
3–2 –
0x0
–
R
1–0 CLKSRC[1:0]
0x0
H0
R/W
Bits 15–9 Reserved
Bit 8
DBRUN
This bit sets whether the RFC operating clock is supplied in DEBUG mode or not.
1 (R/W): Clock supplied in DEBUG mode
0 (R/W): No clock supplied in DEBUG mode
Bits 7–6
Reserved
Bits 5–4
CLKDIV[1:0]
These bits select the division ratio of the RFC operating clock.
Bits 3–2
Reserved
Bits 1–0
CLKSRC[1:0]
These bits select the clock source of the RFC.
Table 18.6.1 Clock Source and Division Ratio Settings
RFCnCLK.
CLKDIV[1:0] bits
RFCnCLK.CLKSRC[1:0] bits
0x0
0x1
0x2
0x3
IOSC
OSC1
OSC3
EXOSC
0x3
1/8
1/1
1/8
1/1
0x2
1/4
1/4
0x1
1/2
1/2
0x0
1/1
1/1
(Note) The oscillation circuits/external input that are not supported in this IC cannot be
selected as the clock source.
Note: The RFCnCLK register settings can be altered only when the RFCnCTL.MODEN bit = 0.
RFC Ch.
n
Control Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
RFCnCTL
15–9 –
0x00
–
R
–
8
RFCLKMD
0
H0
R/W
7
CONEN
0
H0
R/W
6
EVTEN
0
H0
R/W
5–4 SMODE[1:0]
0x0
H0
R/W
3–1 –
0x0
–
R
0
MODEN
0
H0
R/W
Bits 15–9 Reserved
Bit 8
RFCLKMD
This bit sets the RFCLKO
n
pin to output the divided-by-two oscillation clock.
1 (R/W): Divided-by-two clock output
0 (R/W): Oscillation clock output
For more information, refer to “CR Oscillation Frequency Monitoring Function.”