LM3S608 Datasheet, PDF (365/416 Pages) List of Unclassifed Manufacturers – Microcontroller

LM3S608 Microcontroller
As shown in Figure 15-2 on page 365, the input source for VIN- is an external input. In addition to
an external input, input sources for VIN+ can be the +ve input of comparator 0 or an internal reference.
Figure 15-2. Structure of Comparator Unit
-ve input
0
+ve input
1
+ve input (alternate)
CINV
output
IntGen
2
reference input
TrigGen
ACCTL
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 the Comparator Operating Mode tables.
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 the
Comparator Operating Mode tables.
15.2.1
Table 15-1. Comparator 0 Operating Modes
ACCNTL0 Comparator 0
ASRCP VIN- VIN+ Output Interrupt ADC Trigger
00
C0- C0+ C0o
yes
yes
01
C0- C0+ C0o
yes
yes
10
C0- Vref C0o
yes
yes
11
C0- reserved C0o
yes
yes
Internal Reference Programming
The structure of the internal reference is shown in Figure 15-3 on page 366. This is controlled by a
single configuration register (ACREFCTL). Table 15-2 on page 366 shows the programming options
to develop specific internal reference values, to compare an external voltage against a particular
voltage generated internally.
October 01, 2007
365
Preliminary