R8C/38T-A Group
9. Clock Generation Circuit
Under development Preliminary document
Specifications in this document are tentative and subject to change.
R01UH0241EJ0010 Rev.0.10
Page 90 of 730
Aug 05, 2011
9.2.2
System Clock Control Register 1 (CM1)
Notes:
1. If the CM10 bit is 1 (stop mode), the on-chip feedback register is disabled. If the CM10 bit is 1 (stop mode), when
the CM13 bit is 1 (XIN-XOUT pin), the XOUT (P4_7) pin is set to high. When the CM13 bit is 1, P4_6 and P4_7
are set to input state.
2. When the SVC0 bit in the SVDC register is 1 (transition to low-power-consumption mode enabled), do not set the
CM10 bit to 1 (stop mode).
3. Once the CM13 bit is set to 1 by a program, it cannot be set to 0. Set the CM13 bit to 1 to use P4_6 and P4_7 as
the XCIN-XCOUT pin (the XCSEL bit in the PINSR register is 0 and the CM01 bit in the CM10 register is 1) or to
use as the XIN-XOUT pin.
4. The CM14 bit can be set to 1 (low-speed on-chip oscillator off) when bits CM42 to CM40 in the CM4 register are
000b (XIN clock). When bits CM42 to CM40 are set to 001b (fLOCO clock), the CM14 bit is set to 0 (low-speed
on-chip oscillator on). Writing 1 to this bit has no effect.
5. To use a voltage monitor 1 interrupt or a voltage monitor 2 interrupt (when the digital filter is used), set the CM14
bit to 0 (low-speed on-chip oscillator on).
6. When the CM06 bit in the CM0 register is 0 (bits CM16 and CM17 enabled), bits CM16 and CM17 are enabled.
Set the PRC0 bit in the PRCR register to 1 (write enabled) before rewriting the CM1 register.
Address 00009h
Bit
b7b6
b5b4b3
b2b1b0
Symbol
CM17
CM16
—
CM14
CM13
CM12
CM11
CM10
After Reset
0
010
0000
Bit
Symbol
Bit Name
Function
R/W
b0
CM10
All clock stop control bit (1, 2)
0: Clocks oscillate
1: All clocks stop (stop mode)
R/W
b1
CM11
XIN-XOUT on-chip feedback resistor
select bit
0: On-chip feedback resistor enabled
1: On-chip feedback resistor disabled
R/W
b2
CM12
XCIN-XCOUT on-chip feedback
resistor select bit
R/W
b3
CM13
Port/XIN-XOUT switch bit (3)
0: I/O ports P4_6 and P4_7
1: XIN-XOUT pin
R/W
b4
CM14
Low-speed on-chip oscillator oscillation
stop bit (4, 5)
0: Low-speed on-chip oscillator on
1: Low-speed on-chip oscillator off
R/W
b5
—
Reserved
Set to 1.
R/W
b6
CM16
CPU clock division select bits 1 (6)
b7 b6
0 0: Divide-by-1 mode
0 1: Divide-by-2 mode
1 0: Divide-by-4 mode
1 1: Divide-by-16 mode
R/W
b7
CM17
R/W