Low-Voltage Inhibit (LVI)
Functional Description
MC68HC908AB32
—
Rev. 1.0
Technical Data
MOTOROLA
Low-Voltage Inhibit (LVI)
361
21.4.1 Polled LVI Operation
In applications that can operate at V
DD
levels below the LVI
TRIPF
level,
software can monitor V
DD
by polling the LVIOUT bit. In configuration
register 1, the LVIPWRD bit must be at logic 0 to enable the LVI module,
and the LVIRSTD bit must be at logic 1 to disable LVI resets.
21.4.2 Forced Reset Operation
In applications that require V
DD
to remain above the LVI
TRIPF
level,
enabling LVI resets allows the LVI module to reset the MCU when V
DD
falls below the LVI
TRIPF
level and remains at or below that level for 9 or
more consecutive CPU cycles. In configuration register 1, the LVIPWRD
and LVIRSTD bits must be at logic 0 to enable the LVI module and to
enable LVI resets.
21.4.3 False Reset Protection
The V
DD
pin level is digitally filtered to reduce false resets due to power
supply noise. In order for the LVI module to reset the MCU, V
DD
must
remain at or below the LVI
TRIPF
level for 9 or more consecutive CPU
cycles. V
DD
must be above LVI
TRIPR
for only one CPU cycle to bring the
MCU out of reset.
Address:
$FE0F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
LVIOUT
0
0
0
0
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 21-2. LVI I/O Register Summary
Содержание MC68HC908AB32
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