Renesas R8C/20 User Manual

R8C/20 Group, R8C/21 Group 10. Clock Generation Circuit
Rev.2.00 Aug 27, 2008 Page 67 of 458
REJ09B0250-0200
Figure 10.3 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, it can not to 0 in a program.
When entering stop mode, the CM15 bit is set to 1 (drive capacity high).
Set the PRC0 bit in the PRCR register to 1 (enables w riting) before rew riting to the CM1 register.
b7 b6 b5 b4 b3 b2 b1 b0
00
CM10
All clock stop control bit
(4,7,8)
0 : Oscillates clock
1 : Stops all clocks (stop mode)
RW
—
(b2-b1)
Reserved bits Set to 0
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 becomes “H”. When the CM13 bit is set to 0 (input ports, P4_6, P4_7), the 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 the CM10 and CM14 bits are set.
When the CM06 bit is set to 0 (CM16, CM17 bits enabled), the CM16 to CM17 bits become enabled.
If the CM10 bit is 1 (stop mode), the internal feedback resistor becomes disabled.
When the OCD2 bit is set to 0 (selects XIN clock), the CM14 bit is set to 1 (stops low -speed on-chip oscillator). When
the OCD2 bit is set to 1 (selects on-chip oscillator clock), the CM14 bit is set to 0 (low -speed on-chip oscillator on). It
remains unchanged even if it is set to 1.
When using the low voltage 2 detection interrupt (w hen using the digital filter), set the CM14 bit to 0 (low -speed on-
chip oscillator on).

Renesas R8C/20 Specifications

General

Brand	Renesas
Model	R8C/20
Category	Control Unit
Language	English