LM3S1N16 Datasheet, PDF (718/794 Pages) Texas Instruments – Stellaris® LM3S1N16 Microcontroller

Analog Comparators
2. Enable the clock to the appropriate GPIO modules via the RCGC2 register (see page 253). To
find out which GPIO ports to enable, refer to Table 18-5 on page 740.
3. In the GPIO module, enable the GPIO port/pin associated with the input signals as GPIO inputs.
To determine which GPIO to configure, see Table 18-4 on page 737.
4. Configure the PMCn fields in the GPIOPCTL register to assign the analog comparator output
signals to the appropriate pins (see page 422 and Table 18-5 on page 740).
5. Configure the internal voltage reference to 1.65 V by writing the ACREFCTL register with the
value 0x0000.030C.
6. Configure the comparator to use the internal voltage reference and to not invert the output by
writing the ACCTLn register with the value of 0x0000.040C.
7. Delay for 10 µs.
8. Read the comparator output value by reading the ACSTATn register’s OVAL value.
Change the level of the comparator negative input signal C- to see the OVAL value change.
16.5
Register Map
Table 16-3 on page 718 lists the comparator registers. The offset listed is a hexadecimal increment
to the register’s address, relative to the Analog Comparator base address of 0x4003.C000. Note
that the analog comparator clock must be enabled before the registers can be programmed (see
page 244). There must be a delay of 3 system clocks after the analog comparator module clock is
enabled before any analog comparator module registers are accessed.
Table 16-3. Analog Comparators Register Map
Offset Name
Type
Reset
Description
0x000
0x004
0x008
0x010
0x020
0x024
0x040
0x044
ACMIS
ACRIS
ACINTEN
ACREFCTL
ACSTAT0
ACCTL0
ACSTAT1
ACCTL1
R/W1C
RO
R/W
R/W
RO
R/W
RO
R/W
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
Analog Comparator Masked Interrupt Status
Analog Comparator Raw Interrupt Status
Analog Comparator Interrupt Enable
Analog Comparator Reference Voltage Control
Analog Comparator Status 0
Analog Comparator Control 0
Analog Comparator Status 1
Analog Comparator Control 1
See
page
719
720
721
722
723
724
723
724
16.6
Register Descriptions
The remainder of this section lists and describes the Analog Comparator registers, in numerical
order by address offset.
718
January 21, 2012
Texas Instruments-Production Data