LM3S301 Luminary Micro, Inc, LM3S301 Datasheet - Page 298

• Manufacturer Part Number: LM3S301
• Description: Lm3s301 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

Analog Comparators
298
The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT.
As shown in Figure 14-2, 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 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 and Table 14-2.
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
Table 14-2. Comparator 1 Operating Modes
00
01
10
11
00
01
ACCNTL0
ACCNTL1
ASRCP
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 110.
+ve input (alternate)
reference input
+ve input
-ve input
VIN-
VIN-
C0-
C0-
C0-
C0-
C1-
C1-
0
1
2
ACCTL
Preliminary
C1o/C1+
reserved
VIN+
VIN+
C0+
C0+
C0+
Vref
a
CINV
Comparator 0
Comparator 1
C1o/C1+
C1o/C1+
Output
Output
C0o
C0o
C0o
C0o
ACSTAT
TrigGen
IntGen
output
Interrupt
Interrupt
yes
yes
yes
yes
yes
yes
ADCTrigger
ADCTrigger
July 5, 2006
yes
yes
yes
yes
yes
yes