Microchip Technology MCU PIC PIC18F87K22-I/PTRSL TQFP-80 MCP PIC18F87K22-I/PTRSL Data Sheet
Product codes
PIC18F87K22-I/PTRSL
2009-2011 Microchip Technology Inc.
DS39960D-page 379
PIC18F87K22 FAMILY
26.0
HIGH/LOW-VOLTAGE DETECT
(HLVD)
(HLVD)
The PIC18F87K22 family of devices has 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 experi-
ences an excursion past the trip point in that direction, an
interrupt flag is set. If the interrupt is enabled, the pro-
gram execution branches to the interrupt vector address
and the software responds to the interrupt.
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 experi-
ences an excursion past the trip point in that direction, an
interrupt flag is set. If the interrupt is enabled, the pro-
gram execution branches to the interrupt vector address
and the software responds to the interrupt.
The High/Low-Voltage Detect Control register
(
(
) 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
off” by the user under software control, which
minimizes the current consumption for the device.
The module’s block diagram is shown in
.
REGISTER 26-1:
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-0
VDIRMAG
BGVST
IRVST
HLVDEN
HLVDL3
(
HLVDL2
HLVDL1
HLVDL0
bit 7
bit 0
Legend:
R = Readable bit
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 references are 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 is enabled
0
= HLVD is disabled
bit 3-0
HLVDL<3:0>:
Voltage Detection Limit bits
(
1111
= External analog input is used (input comes from the HLVDIN pin)
1110
= Maximum setting
.
.
.
0000
= Minimum setting
Note 1:
For the electrical specifications, see Parameter D420.