R01UH0040EJ0100 Rev.1.00
Page 212 of 1657
Sep 8, 2011
RX630 Group
8. Voltage Detection Circuit (LVD)
8.
Voltage Detection Circuit (LVD)
The voltage detection circuit (LVD) monitors the voltage level input to the VCC pin using a program.
8.1
Overview
In voltage detection 0, whether to enable or disable the reset of voltage monitoring 0 can be selected after the reset using
the option function select register 1 (OFS1).
In voltage detection 1 and voltage detection 2, the detection voltage is set using the voltage detection level select register
(LVDLVLR).
Reset of voltage monitoring 0, reset/interrupt of voltage monitoring 1, and reset/interrupt of voltage monitoring 2 can be
used.
Table 8.1 lists the specifications of the voltage detection circuit.
Figure 8.1 is a block diagram of the voltage detection
circuit.
Figure 8.2 is a block diagram of the voltage monitoring 1 interrupt/reset circuit.
Figure 8.3 is a block diagram of
the voltage monitoring 2 interrupt/reset circuit.
Table 8.1
Voltage Detection Circuit Specifications
Item
Voltage Monitoring 0
Voltage Monitoring 1
Voltage Monitoring 2
VCC
monitoring
Monitored
voltage
Vdet0
Vdet1
Vdet2
Detected
event
Voltage drops past Vdet0
Voltage rises or drops past Vdet1
Voltage rises or drops past Vdet2
Detection
voltage
One level fixed
Specify voltage using
LVDLVLR.LVD1LVLR[3:0] bits
Specify voltage using
LVDLVLR.LVD2LVL[3:0] bits
Monitoring
flag
None
LVD1SR.LVD1MON flag: Monitors
whether voltage is higher or lower
than Vdet1
LVD2SR.LVD2MON flag: Monitors
whether voltage is higher or lower
than Vdet2
LVD1SR.LVD1DET flag: Vdet1
passage detection
LVD2SR.LVD2DET flag: Vdet2
passage detection
Process upon
voltage
detection
Reset
Voltage monitoring 0 reset
Voltage monitoring 1 reset
Voltage monitoring 2 reset
Reset when Vdet0 > VCC
CPU restart after specified
time with VCC > Vdet0
Reset when Vdet1 > VCC
CPU restart timing selectable:
after specified time with VCC >
Vdet1 or Vdet1 > VCC
Reset when Vdet2 > VCC
CPU restart timing selectable:
after specified time with VCC >
Vdet2 or Vdet2 > VCC
Interrupt
No interrupt
Voltage monitoring 1 interrupt
Voltage monitoring 2 interrupt
Non-maskable interrupt
Interrupt request issued when
Vdet1 > VCC and VCC > Vdet1 or
either
Interrupt request issued when
Vdet2 > VCC and VCC > Vdet2 or
either
Digital filter
Enable/
Disable
switching
Digital filter function not
available
Available
Sampling
time
—
1/n LOCO frequency
2
(n: 1, 2, 4, 8)
1/n LOCO frequency
2
(n: 1, 2, 4, 8)