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LM3S5G51 Datasheet, PDF (1004/1266 Pages) Texas Instruments – Stellaris® LM3S5G51 Microcontroller
Analog Comparators
19.3
Functional Description
The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT.
VIN- < VIN+, VOUT = 1
VIN- > VIN+, VOUT = 0
As shown in Figure 19-2 on page 1004, the input source for VIN- is an external input, Cn-. In addition
to an external input, Cn+, input sources for VIN+ can be the C0+ or an internal reference, VIREF.
Figure 19-2. Structure of Comparator Unit
- ve input
+ ve input 0
1
+ ve input (alternate)
2
reference input
CINV
output
IntGen
TrigGen
ACCTL
ACSTAT
19.3.1
A comparator is configured through two status/control registers, Analog Comparator Control
(ACCTL) and Analog Comparator Status (ACSTAT). The internal reference is configured through
one control register, Analog Comparator Reference Voltage Control (ACREFCTL). Interrupt
status and control are configured through three registers, Analog Comparator Masked Interrupt
Status (ACMIS), Analog Comparator Raw Interrupt Status (ACRIS), and Analog Comparator
Interrupt Enable (ACINTEN).
Typically, the comparator output is used internally to generate an interrupt as controlled by the ISEN
bit in the ACCTL register. The output may also be used to drive an external pin, Co or generate an
analog-to-digital converter (ADC) trigger.
Important: The ASRCP bits in the ACCTL register must be set before using the analog comparators.
Internal Reference Programming
The structure of the internal reference is shown in Figure 19-3 on page 1005. The internal reference
is controlled by a single configuration register (ACREFCTL).
1004
Texas Instruments-Production Data
January 23, 2012