Texas Instruments TM4C1294NCPDT User Manual

Table 22-4. Analog Comparator Voltage Reference Characteristics, V
DDA
= 3.3V, EN= 1, and
RNG = 1
UnitV
IREF
MaxIdeal V
IREF
V
IREF
MinVREF Value
V0.0740.0000.0000x0
V0.2230.1490.0760x1
V0.3720.2980.2250x2
V0.5210.4480.3740x3
V0.6700.5970.5230x4
V0.8200.7460.6720x5
V0.9690.8950.8220x6
V1.1181.0440.9710x7
V1.2671.1931.1200x8
V1.4161.3431.2690x9
V1.5651.4921.4180xA
V1.7151.6411.5670xB
V1.8641.7901.7170xC
V2.0131.9391.8660xD
V2.1622.0892.0150xE
V2.3112.2382.1640xF
22.4 Initialization and Configuration
The following example shows how to configure an analog comparator to read back its output value
from an internal register.
1. Enable the analog comparator clock by writing a value of 0x0000.0001 to the RCGCACMP
register in the System Control module (see page 397).
2. Enable the clock to the appropriate GPIO modules via the RCGCGPIO register (see page 382).
To find out which GPIO ports to enable, refer to Table 26-5 on page 1808.
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 26-4 on page 1797.
4. Configure the PMCn fields in the GPIOPCTL register to assign the analog comparator output
signals to the appropriate pins (see page 787 and Table 26-5 on page 1808).
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.
June 18, 20141658
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Analog Comparators

Texas Instruments TM4C1294NCPDT Specifications

General

Brand	Texas Instruments
Model	TM4C1294NCPDT
Category	Microcontrollers
Language	English