LM3S6422 Datasheet, PDF (523/609 Pages) Texas Instruments – Stellaris® LM3S6422 Microcontroller

Stellaris^® LM3S6422 Microcontroller
Table 14-2. Analog Comparators Signals (108BGA)
Pin Name
Pin Number Pin Type Buffer Type^a Description
C0+
A7
I
Analog Analog comparator 0 positive input.
C0-
A6
I
Analog Analog comparator 0 negative input.
C0o
F1
O
TTL
Analog comparator 0 output.
C1+
M1
I
Analog Analog comparator 1 positive input.
C1-
B7
I
Analog Analog comparator 1 negative input.
C1o
M1
O
TTL
Analog comparator 1 output.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
14.3 Functional Description
Important: It is recommended that the Digital-Input enable (the GPIODEN bit in the GPIO module)
for the analog input pin be disabled to prevent excessive current draw from the I/O
pads.
The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT.
VIN- < VIN+, VOUT = 1
VIN- > VIN+, VOUT = 0
As shown in Figure 14-2 on page 523, 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
- ve input
+ ve input ⁰
1
+ ve input (alternate)
2
reference input
CINV
output
IntGen
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).
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: The ASRCP bits in the ACCTLn register must be set before using the analog
comparators.
June 18, 2012
523
Texas Instruments-Production Data