Datasheet
2012 Microchip Technology Inc. DS30684A-page 379
PIC18(L)F2X/45K50
25.0 HIGH/LOW-VOLTAGE DETECT
(HLVD)
The PIC18(L)F2X/45K50 devices have a High/Low-
Voltage Detect module (HLVD). This is a programmable
circuit that sets both a device voltage trip point and the
direction of change from that point. If the device
experiences an excursion past the trip point in that
direction, an interrupt flag is set. If the interrupt is
enabled, the program execution branches to the
interrupt vector address and the software responds to
the interrupt.
The High/Low-Voltage Detect Control register
(Register 25-1) completely controls the operation of the
HLVD module. This allows the circuitry to be “turned
off” by the user under software control, which
minimizes the current consumption for the device.
The module’s block diagram is shown in Figure 25-1.
25.1 Register – HLVD Control
REGISTER 25-1: HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER
R/W-0 R-0 R-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-1
VDIRMAG BGVST IRVST HLVDEN HLVDL<3:0>
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7 VDIRMAG: Voltage Direction Magnitude Select bit
1 = Event occurs when voltage equals or exceeds trip point (HLVDL<3:0>)
0 = Event occurs when voltage equals or falls below trip point (HLVDL<3:0>)
bit 6 BGVST: Band Gap Reference Voltages Stable Status Flag bit
1 = Internal band gap voltage references are stable
0 = Internal band gap voltage reference is not stable
bit 5 IRVST: Internal Reference Voltage Stable Flag bit
1 = Indicates that the voltage detect logic will generate the interrupt flag at the specified voltage range
0 = Indicates that the voltage detect logic will not generate the interrupt flag at the specified voltage
range and the HLVD interrupt should not be enabled
bit 4 HLVDEN: High/Low-Voltage Detect Power Enable bit
1 = HLVD enabled
0 = HLVD disabled
bit 3-0 HLVDL<3:0>: Voltage Detection Level bits
(1)
1111 = External analog input is used (input comes from the HLVDIN pin)
1110 = Maximum setting
.
.
.
0000 = Minimum setting
Note 1: See Table 29-5 for specifications.