LM3S308 Datasheet, PDF (474/537 Pages) Texas Instruments – ARM and Thumb are registered trademarks and Cortex is a trademark

Analog Comparator
14
14.1
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. See the Comparator Operating
Mode tables in “Functional Description” on page 475 for more information.
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 14-1. Analog Comparator Module Block Diagram
C0-
-ve input _{Comparator 0}
C0+
+ve input
output
+ve input (alternate)
ACCTL0
ACSTAT0
interrupt
reference input
<none>
internal
bus
Voltage
Ref
ACREFCTL
Interrupt Control
ACRIS
ACMIS
ACINTEN
14.2
interrupt
Signal Description
Table 14-1 on page 475 lists the external signals of the Analog Comparators and describes the
function of each. The Analog Comparator output signal is an alternate functions for a GPIO signal
474
June 18, 2012
Texas Instruments-Production Data