R8C/1A Group, R8C/1B Group
7. Voltage Detection Circuit
Rev.1.30
Dec 08, 2006
Page 44 of 315
REJ09B0252-0130
7.
Voltage Detection Circuit
The voltage detection circuit monitors the input voltage to the VCC pin. This circuit can be used to monitor the VCC
input voltage by a program. Alternately, voltage monitor 1 reset, voltage monitor 2 interrupt, and voltage monitor 2
reset can also be used.
Table 7.1 lists the Specifications of Voltage Detection Circuit and Figures 7.1 to 7.3 show the Block Diagrams. Figures
7.4 to 7.6 show the Associated Registers.
Table 7.1
Specifications of Voltage Detection Circuit
Item
Voltage Detection 1
Voltage Detection 2
VCC monitor
Voltage to monitor
Vdet1
Vdet2
Detection target
Passing through Vdet1
by rising or falling
Passing through Vdet2
by rising or falling
Monitor
None
VCA13 bit in VCA1
register
Whether VCC is higher
or lower than Vdet2
Process when voltage is
detected
Reset
Voltage monitor 1 reset
Voltage monitor 2 reset
Reset at Vdet1 > VCC;
restart CPU operation at
VCC > Vdet1
Reset at Vdet2 > VCC;
restart CPU operation
after a specified time
Interrupt
None
Voltage monitor 2
interrupt
Interrupt request at
Vdet2 > VCC and VCC >
Vdet2 when digital filter
is enabled;
interrupt request at
Vdet2 > VCC or VCC >
Vdet2 when digital filter
is disabled
Digital filter
Switch
enabled/disabled
Available
Available
Sampling time
(Divide-by-n of fRING-S)
x 4
n: 1, 2, 4, and 8
(Divide-by-n of fRING-S)
x 4
n: 1, 2, 4, and 8
