Renesas R8C/20 User Manual

R8C/20 Group, R8C/21 Group 10. Clock Generation Circuit
Rev.2.00 Aug 27, 2008 Page 70 of 458
REJ09B0250-0200
Figure 10.6 FRA2 Register
Figure 10.7 VCA2 Register
High-Speed On-Chip Oscillator Control Register 2
(1)
Symbol Address After Reset
FRA2
0025h 00h
Bit Symbol Bit Name Function RW
NOTES:
1.
2.
3.
Do not set on the K version products.
RW
FRA21
Set the PRC0 bit in the PRCR register to 1 (enables w riting) before rew riting to the FRA2 register.
Since the value after reset is 000b, set 010b to 111b on the K version products.
—
(b7-b3)
RW
Reserved bits Set to 0
RW
The division of high-speed on-chip
oscillator clock can be selected.
b2 b1 b0
0 0 0 : Divide-by-2 mode
(3)
0 0 1 : Divide-by-3 mode
(3)
0 1 0 : Divide-by-4 mode
0 1 1 : Divide-by-5 mode
1 0 0 : Divide-by-6 mode
1 0 1 : Divide-by-7 mode
1 1 0 : Divide-by-8 mode
1 1 1 : Divide-by-9 mode
0
FRA22 RW
High-speed on-chip oscillator
frequency sw itching bits
(2)
FRA20
0000
b3 b2 b1 b0b7 b6 b5 b4
Voltage Detection Register 2
(1)
Symbol Address
VCA2 0032h
Bit Symbol Bit Name Function RW
NOTES:
1.
2.
3.
4.
5. Use the VCA20 bit only w hen entering to w ait mode. To set the VCA20 bit, follow the procedure show n in
Figure
10.10 Procedure for Enabling Reduced Internal Power Consumption Using VCA20 bit
.
VCA20
Internal pow er low consumption
enable bit
(5)
0 : Disables low consumption
1 : Enables low consumption
RW
When using the voltage monitor 2 interrupt/reset or the VCA13 bit in the VCA1 register, set the VCA27 bit to 1.
After the VCA27 bit is from 0 to 1, the voltage detection circuit elapses for td(E-A) before starting operation.
The VCA27 bit remains unchanged after softw are reset, w atchdog timer reset, and voltage monitor 2 reset.
Voltage detection 1 enable bit
(2)
0 : Voltage detection 1 circuit disabled
1 : Voltage detection 1 circuit enabled
RW
The LVD1ON bit in the OFS register is set to 1: 00h
Power-on reset, v oltage monitor 1 reset or the LVD1ON
bit in the OFS register is set to 0: 01000000b
After Reset
(4)
Set the PRC3 bit in the PRCR register to 1 (enables w riting) before w riting to the VCA2 register.
When using the voltage monitor 1 reset, set the VCA26 bit to 1.
After the VCA26 bit is set from 0 to 1, the voltage detection circuit elapses for td(E-A) before starting operation.
000
—
(b5-b1)
Reserved bits
VCA27
Voltage detection 2 enable bit
(3)
0 : Voltage detection 2 circuit disabled
1 : Voltage detection 2 circuit enabled
RW
b0
00
Set to 0
RW
VCA26
b7 b6 b5 b4 b3 b2 b1

Renesas R8C/20 Specifications

General

Brand	Renesas
Model	R8C/20
Category	Control Unit
Language	English