Datasheet

17 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
17.1 Block Diagram
Figure 17-1. Analog Comparator Module Block Diagram
Voltage
Ref
ACREFCTL
output
+ve input (alternate)
+ve input
interrupt
trigger
-ve input
reference input
Comparator 0
ACSTAT0
ACCTL0
C0+
internal
bus
trigger
C0-
C0o
Interrupt Control
ACRIS
ACMIS
ACINTEN
interrupt
17.2 Signal Description
Table 17-1 on page 648 and Table 17-2 on page 648 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
647June 18, 2012
Texas Instruments-Production Data
Stellaris
®
LM3S8962 Microcontroller
NRND: Not recommended for new designs.