LM3S818 Luminary Micro, Inc, LM3S818 Datasheet - Page 301

• Manufacturer Part Number: LM3S818
• Description: Lm3s818 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

14.2.1
February 6, 2007
Figure 14-2. Structure of Comparator Unit
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 14-1.
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:
Table 14-1. Comparator 0 Operating Modes
Internal Reference Programming
The structure of the internal reference is shown in Figure 14-3. This is controlled by a single
configuration register (ACREFCTL). Table 14-2 shows the programming options to develop
specific internal reference values, to compare an external voltage against a particular voltage
generated internally.
00
01
10
11
ACCNTL0
ASRCP
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 83.
+ve input (alternate)
reference input
+ve input
-ve input
VIN-
C0-
C0-
C0-
C0-
0
1
2
ACCTL
Preliminary
reserved
VIN+
C0+
C0+
Vref
CINV
Comparator 0
ACSTAT
TrigGen
IntGen
Output
C0o
C0o
C0o
C0o
output
LM3S818 Data Sheet
Interrupt
yes
yes
yes
yes
301