2 POWER SUPPLY, RESET, AND CLOCKS
S1C17M20/M21/M22/M23/M24/M25
Seiko Epson Corporation
2-17
TECHNICAL MANUAL (Rev. 1.0)
CLG OSC1 Control Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
CLGOSC1
15 –
0
–
R
–
14 OSDRB
1
H0
R/WP
13 OSDEN
0
H0
R/WP
12 OSC1BUP
1
H0
R/WP
11 OSC1SELCR
0
H0
R/WP
10–8 CGI1[2:0]
0x0
H0
R/WP
7–6 INV1B[1:0]
0x2
H0
R/WP
5–4 INV1N[1:0]
0x1
H0
R/WP
3–2 –
0x0
–
R
1–0 OSC1WT[1:0]
0x2
H0
R/WP
Bit 15
Reserved
Bit 14
OSDRB
This bit enables the OSC1 oscillator circuit restart function by the oscillation stop detector when
OSC1 crystal oscillation stop is detected.
1 (R/WP): Enable (Restart the OSC1 oscillator circuit when oscillation stop is detected.)
0 (R/WP): Disable
Bit 13
OSDEN
This bit controls the oscillation stop detector in the OSC1 oscillator circuit.
1 (R/WP): OSC1 oscillation stop detector on
0 (R/WP): OSC1 oscillation stop detector off
Note
: Do not write 1 to the CLGOSC1.OSDEN bit before stabilized OSC1CLK is supplied. Further-
more, the CLGOSC1.OSDEN bit should be set to 0 when the CLGOSC.OSC1EN bit is set to 0.
Bit 12
OSC1BUP
This bit enables the oscillation startup control circuit in the OSC1 crystal oscillator circuit.
1 (R/WP): Enable (Activate booster operation at startup.)
0 (R/WP): Disable
Bit 11
OSC1SELCR
This bit selects an oscillator type of the OSC1 oscillator circuit.
1 (R/WP): Internal oscillator
0 (R/WP): Crystal oscillator
Bits 10–8 CGI1[2:0]
These bits set the internal gate capacitance in the OSC1 crystal oscillator circuit.
Table 2.6.4 OSC1 Internal Gate Capacitance Setting
CLGOSC1.CGI1[2:0] bits
Capacitance
0x7
Max.
0x6
↑
0x5
0x4
0x3
0x2
0x1
↓
0x0
Min.
For more information, refer to “OSC1 oscillator circuit characteristics, Crystal oscillator internal gate
capacitance C
GI1C
” in the “Electrical Characteristics” chapter.
Bits 7–6
INV1B[1:0]
These bits set the oscillation inverter gain that will be applied at boost startup of the OSC1 crystal os-
cillator circuit.