
R8C/2C Group, R8C/2D Group
10. Clock Generation Circuit
Rev.2.00
Dec 05, 2007
REJ09B0339-0200
Figure 10.4
CM1 Register
System Clock Control Register 1(1)
Symbol
Address
After Reset
CM1
0007h
00100000b
Bit Symbol
Bit Name
Function
RW
NOTES:
1.
2.
3.
4.
5.
6.
7.
8.
9. Once the CM13 bit is set to 1 by a program, it cannot be set to 0.
When entering stop mode, the CM15 bit is set to 1 (drive capacity high).
Set the PRC0 bit in the PRCR register to 1 (w rite enable) before rew riting the CM1 register.
b7 b6 b5 b4 b3 b2 b1 b0
CM10
All clock stop control bit(4, 7, 8)
0 : Clock operates
1 : Stops all clocks (stop mode)
RW
CM11
XIN-XOUT on-chip feedback resistor
select bit
0 : On-chip feedback resistor enabled
1 : On-chip feedback resistor disabled
RW
CM12
XCIN-XCOUT on-chip feedback
resistor select bit
0 : On-chip feedback resistor enabled
1 : On-chip feedback resistor disabled
RW
CM13
Port XIN-XOUT sw itch bit(7, 9)
0 : Input ports P4_6, P4_7
1 : XIN-XOUT pin
RW
CM14
Low -speed on-chip oscillation stop
bit(5, 6, 8)
0 : Low -speed on-chip oscillator on
1 : Low -speed on-chip oscillator off
RW
CM15
XIN-XOUT drive capacity select bit(2) 0 : Low
1 : High
RW
CM17
RW
b7 b6
0 0 : No division mode
0 1 : Divide-by-2 mode
1 0 : Divide-by-4 mode
1 1 : Divide-by-16 mode
System clock division select bits 1(3)
CM16
RW
When the CM10 bit is set to 1 (stop mode) and the CM13 bit is set to 1 (XIN-XOUT pin), the XOUT (P4_7) pin goes “H”.
When the CM13 bit is set to 0 (input ports, P4_6, P4_7), P4_7 (XOUT) enters input mode.
In count source protect mode (Refer to 13.2 Count Source Protection Mode Enabled), the value remains
unchanged even if bits CM10 and CM14 are set.
When the CM06 bit is set to 0 (bits CM16, CM17 enabled), bits CM16 to CM17 are enabled.
If the CM10 bit is set to 1 (stop mode), the on-chip feedback resistor is disabled.
When the OCD2 bit is set to 0 (XIN clock selected), the CM14 bit is set to 1 (low -speed on-chip oscillator stopped).
When the OCD2 bit is set to 1 (on-chip oscillator clock selected), the CM14 bit is set to 0 (low -speed on-chip
oscillator on). It remains unchanged even if 1 is w ritten to it.
When using the voltage monitor 1 interrupt or voltage monitor 2 interrupt (w hen using the digital filter), set the CM14
bit to 0 (low -speed on-chip oscillator on).