LM3S101 Luminary Micro, Inc., LM3S101 Datasheet - Page 262

• Manufacturer Part Number: LM3S101
• Description: Microcontroller
• Manufacturer: Luminary Micro, Inc.

Analog Comparators
262
As shown in Figure 13-2, 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 13-2. 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 13-1 and Table 13-2.
Typically, the comparator output is used internally to generate controller interrupts. It may also be
used to drive an external pin.
Important:
Table 13-1. Comparator 0 Operating Modes
Table 13-2. Comparator 1 Operating Modes
ACCNTL0
ACCNTL1
ASRCP
ASRCP
00
01
10
11
00
01
10
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 101.
+ve input (alternate)
reference input
C0o/C1-
C0o/C1-
C0o/C1-
VIN-
VIN-
C0-
C0-
C0-
C0-
+ve input
-ve input
a
Preliminary
0
1
2
ACCTL
reserved
VIN+
VIN+
C0+
C0+
Vref
C0+
Vref
n/a
Comparator 0
Comparator 1
CINV
ACSTAT
C0o/C1-
C0o/C1-
C0o/C1-
C0o/C1-
Output
Output
IntGen
n/a
n/a
n/a
output
October 5, 2006
Interrupt
Interrupt
yes
yes
yes
yes
yes
yes
yes