
R8C/3JM Group
9. Clock Generation Circuit
R01UH0285EJ0100 Rev.1.00
Aug 08, 2011
9.2.14
Voltage Detect Register 2 (VCA2)
Notes:
1. Use the VCA20 bit only when the MCU enters wait mode. To set the VCA20 bit, follow the procedure shown in
33.2.9 Reducing Internal Power Consumption Using VCA20 Bit.
2. When the VCA20 bit is set to 1 (low consumption enabled), do not set the CM10 bit in the CM1 register to 1 (stop
mode).
3. When writing to the VCA25 bit, set a value after reset.
4. To use the voltage detection 1/comparator A1 interrupt or the VW1C3 bit in the VW1C register, set the VCA26 bit
to 1.
After the VCA26 bit is set to 1 from 0, allow td(E-A) to elapse before the voltage detection 1/comparator A1 circuit
starts operation.
5. To use the voltage detection 2/comparator A2 interrupt or the VCA13 bit in the VCA1 register, set the VCA27 bit
to 1.
After the VCA27 bit is set to 1 from 0, allow td(E-A) to elapse before the voltage detection 2/comparator A2 circuit
starts operation.
Set the PRC3 bit in the PRCR register to 1 (write enabled) before rewriting the VCA2 register.
Address 0034h
Bit
b7b6
b5b4b3b2
b1
b0
Symbol
VCA27
VCA26
VCA25
VCA24
VCA23
VCA22
VCA21
VCA20
After Reset
0
000
0000
The above applies when the LVDAS bit in the OFS register is set to 1.
After Reset
0
010
0000
The above applies when the LVDAS bit in the OFS register is set to 0.
Bit
Symbol
Bit Name
Function
R/W
b0
VCA20
Internal power low consumption
enable bit (1)
0: Low consumption disabled
1: Low consumption enabled (2)
R/W
b1
VCA21
Comparator A1 reference voltage
input select bit
0: Internal reference voltage
1: LVREF pin input voltage
R/W
b2
VCA22
LVCMP1 comparison voltage
external input select bit
0: Supply voltage (VCC)
1: LVCMP1 pin input voltage
R/W
b3
VCA23
Comparator A2 reference voltage
input select bit
0: Internal reference voltage
1: LVREF pin input voltage
R/W
b4
VCA24
LVCMP2 comparison voltage
external input select bit
0: Supply voltage (VCC) (Vdet2_0)
1: LVCMP2 pin input voltage (Vdet2_EXT)
R/W
b5
VCA25
Voltage detection 0 enable bit (3)
0: Voltage detection 0 circuit disabled
1: Voltage detection 0 circuit enabled
R/W
b6
VCA26
Voltage detection 1/comparator A1
enable bit (4)
0: Voltage detection 1/comparator A1 circuit disabled
1: Voltage detection 1/comparator A1 circuit enabled
R/W
b7
VCA27
Voltage detection 2/comparator A2
enable bit (5)
0: Voltage detection 2/comparator A2 circuit disabled
1: Voltage detection 2/comparator A2 circuit enabled
R/W