LM3S9B81 Datasheet, PDF (1003/1155 Pages) Texas Instruments – Stellaris® LM3S9B81 Microcontroller

Stellaris® LM3S9B81 Microcontroller
21.1
Block Diagram
Figure 21-1. Analog Comparator Module Block Diagram
C2-
-ve input _{Comparator 2}
C2+
+ve input
output
C2o
+ve input (alternate)
ACCTL2
trigger
trigger
ACSTAT2
interrupt
reference input
C1-
-ve input _{Comparator 1}
C1+
+ve input
output
C1o
+ve input (alternate)
ACCTL1
trigger
trigger
ACSTAT1
interrupt
reference input
C0-
-ve input _{Comparator 0}
C0+
+ve input
output
C0o
+ve input (alternate)
ACCTL0
trigger
trigger
ACSTAT0
interrupt
reference input
internal
bus
Voltage
Ref
ACREFCTL
Interrupt Control
ACRIS
ACMIS
ACINTEN
interrupt
21.2
Signal Description
Table 21-1 on page 1003 and Table 21-2 on page 1004 list the external signals of the Analog Comparators
and describe the function of each. The Analog Comparator output signals are alternate functions
for some GPIO signals and default to be GPIO signals at reset. The column in the table below titled
"Pin Mux/Pin Assignment" lists the possible GPIO pin placements for the Analog Comparator signals.
The AFSEL bit in the GPIO Alternate Function Select (GPIOAFSEL) register (page 318) should be
set to choose the Analog Comparator function. The number in parentheses is the encoding that
must be programmed into the PMCn field in the GPIO Port Control (GPIOPCTL) register (page 336)
to assign the Analog Comparator signal to the specified GPIO port pin. The positive and negative
input signals are configured by clearing the DEN bit in the GPIO Digital Enable (GPIODEN) register.
For more information on configuring GPIOs, see “General-Purpose Input/Outputs
(GPIOs)” on page 294.
Table 21-1. Signals for Analog Comparators (100LQFP)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
C0+
90
PB6
I
Analog Analog comparator 0 positive input.
June 29, 2010
Texas Instruments-Advance Information
1003