LM3S1637 Datasheet, PDF (546/696 Pages) Texas Instruments – ARM and Thumb are registered trademarks and Cortex is a trademark

Analog Comparator
15
15.1
15.2
Analog Comparator
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
Note: Not all comparators have the option to drive an output pin.
The comparator can provide its output to a device pin, acting as a replacement for an analog
comparator on the board, or it can be used to signal the application via interrupts or triggers to the
ADC to cause it to start capturing a sample sequence. The interrupt generation and ADC triggering
logic is separate. This means, for example, that an interrupt can be generated on a rising edge and
the ADC triggered on a falling edge.
The Stellaris^® Analog Comparators module has the following features:
■ One integrated analog comparator
■ Configurable for output to drive an output pin, generate an interrupt, or initiate an ADC sample
sequence
■ Compare external pin input to external pin input or to internal programmable voltage reference
■ Compare a test voltage against any one of these voltages
– An individual external reference voltage
– A shared single external reference voltage
– A shared internal reference voltage
Block Diagram
Figure 15-1. Analog Comparator Module Block Diagram
C0-
-ve input _{Comparator 0}
C0+
+ve input
output
C0o
+ve input (alternate)
ACCTL0
trigger
trigger
ACSTAT0
interrupt
reference input
internal
bus
Voltage
Ref
ACREFCTL
Interrupt Control
ACRIS
ACMIS
ACINTEN
interrupt
Signal Description
Table 15-1 on page 547 and Table 15-2 on page 547 list the external signals of the Analog Comparators
and describe the function of each. The Analog Comparator output signal is an alternate functions
for a GPIO signal and default to be a GPIO signal at reset. The column in the table below titled "Pin
Assignment" lists the possible GPIO pin placements for the Analog Comparator signals. The AFSEL
546
June 18, 2012
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