LM3S316 Datasheet, PDF (346/421 Pages) List of Unclassifed Manufacturers – Microcontroller

Analog Comparator
Figure 15-2. Structure of Comparator Unit
-ve input
0
+ve input
1
+ve input (alternate)
CINV
2
reference input
ACCTL
output
IntGen
TrigGen
ACSTAT
A comparator is configured through two status/control registers (ACCTL and ACSTAT). The
internal reference is configured through one control register (ACREFCTL). Interrupt status and
control is configured through three registers (ACMIS, ACRIS, and ACINTEN). The operating
modes of the comparators are shown in Table 15-1.
Typically, the comparator output is used internally to generate controller interrupts. It may also be
used to drive an external pin or generate an analog-to-digital converter (ADC) trigger.
Important: Certain register bit values must be set before using the analog comparators. The
proper pad configuration for the comparator input and output pins are described in
Table 8-1 on page 122.
Table 15-1. Comparator 0 Operating Modes
ACCNTL0
Comparator 0
ASRCP
00
01
10
11
VIN-
C0-
C0-
C0-
C0-
VIN+
C0+
C0+
Vref
reserved
Output
C0o
C0o
C0o
C0o
Interrupt
yes
yes
yes
yes
ADC Trigger
yes
yes
yes
yes
15.2.1
Internal Reference Programming
The structure of the internal reference is shown in Figure 15-3. This is controlled by a single
configuration register (ACREFCTL). Table 15-2 shows the programming options to develop
specific internal reference values, to compare an external voltage against a particular voltage
generated internally.
346
April 27, 2007
Preliminary