
R8C/3GM Group
6. Voltage Detection Circuit
R01UH0284EJ0100 Rev.1.00
Aug 09, 2011
6.
Voltage Detection Circuit
The voltage detection circuit monitors the voltage input to the VCC pin. This circuit can be used to monitor the VCC
input voltage by a program.
6.1
Overview
The detection voltage of voltage detection 0 can be selected among four levels using the OFS register.
The detection voltage of voltage detection 1 can be selected among 16 levels using the VD1LS register.
As a detection target, the voltage input to VCC and the LVCMP2 pin can be switched for voltage detection 2 only.
The voltage monitor 0 reset, and voltage monitor 1 interrupt and voltage monitor 2 interrupt can also be used.
Note that voltage monitor 1 and voltage monitor 2 share the voltage detection circuit with comparator A1 and
comparator A2. Either voltage monitor 1 and voltage monitor 2 or comparator A1 and comparator A2 can be
selected.
Table 6.1
Voltage Detection Circuit Specifications
Item
Voltage Monitor 0
Voltage Monitor 1
Voltage Monitor 2
VCC
monitor
Voltage to
monitor
Vdet0
Vdet1
Vdet2
Detection target Whether passing
through Vdet0 by rising
or falling
Whether passing through
Vdet1 by rising or falling
Whether passing through Vdet2 by
rising or falling
The input voltage to VCC and the
LVCMP2 pin can be switched by
the VCA24 bit in the VCA2 register.
Detection
voltage
Selectable among
4 levels using the OFS
register.
Selectable among
16 levels using the
VD1LS register.
The detection voltage level varies
depending on when VCC is
selected or when LVCMP2 is
selected.
Each value is set as the fixed level.
Monitor
None
The VW1C3 bit in
the VW1C register
The VCA13 bit in the VCA1 register
Whether VCC is higher or
lower than Vdet1
Whether VCC is higher or lower
than Vdet2
Process at
voltage
detection
Reset
Voltage monitor 0 reset None
None
Reset at Vdet0 > VCC;
CPU operation restarts
at VCC > Vdet0
Interrupts
None
Voltage monitor 1
interrupt
Voltage monitor 2 interrupt
Non-maskable or
maskable selectable
Non-maskable or maskable
selectable
Interrupt request at:
Vdet1 > VCC
and/or
VCC > Vdet1
Interrupt request at:
Vdet2 > VCC (LVCMP2)
and/or
VCC (LVCMP2) > Vdet2
Digital filter Switching
enable/disable
No digital filter function Supported
Supported
Sampling time
—
(fOCO-S divided by n) × 2
n: 1, 2, 4, and 8
(fOCO-S divided by n) × 2
n: 1, 2, 4, and 8