Datasheet

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.
17.3.1 Internal Reference Programming
The structure of the internal reference is shown in Figure 17-3 on page 649. This is controlled by a
single configuration register (ACREFCTL). Table 17-3 on page 649 shows the programming options
to develop specific internal reference values, to compare an external voltage against a particular
voltage generated internally.
Figure 17-3. Comparator Internal Reference Structure
8R R R
8R
R
•••
•••
0
Decoder
115 14
AVDD
EN
internal
reference
VREF
RNG
Table 17-3. Internal Reference Voltage and ACREFCTL Field Values
Output Reference Voltage Based on VREF Field Value
ACREFCTL Register
RNG Bit ValueEN Bit Value
0 V (GND) for any value of VREF; however, it is recommended that RNG=1 and
VREF=0 for the least noisy ground reference.
RNG=XEN=0
649June 18, 2012
Texas Instruments-Production Data
Stellaris
®
LM3S8962 Microcontroller
NRND: Not recommended for new designs.