Table 22-1. Analog Comparators Signals (128TQFP) (continued)
Description
Buffer Type
Pin Type
Pin Mux / Pin
Assignment
Pin Number
Pin Name
Analog comparator 0 negative input.
Analog
I
PC7
22
C0-
Analog comparator 0 output.
TTL
O
PD0 (5)
PL2 (5)
1
83
C0o
Analog comparator 1 positive input.
Analog
I
PC5
24
C1+
Analog comparator 1 negative input.
Analog
I
PC4
25
C1-
Analog comparator 1 output.
TTL
O
PD1 (5)
PL3 (5)
2
84
C1o
Analog comparator 2 positive input.
Analog
I
PP0
118
C2+
Analog comparator 2 negative input.
Analog
I
PP1
119
C2-
Analog comparator 2 output.
TTL
O
PD2 (5)
3
C2o
22.3
Functional Description
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 22-2 on page 1655, the input source for VIN- is an external input,
Cn-
, where n
is the analog comparator number. In addition to an external input,
Cn+
, input sources for VIN+ can
be the C0+ or an internal reference, V
IREF
.
Figure 22-2. Structure of Comparator Unit
ACCTL
CINV
TrigGen
output
ACSTAT
IntGen
1
0
2
reference input
+ve input (alternate)
+ve input
-ve input
internal
bus
interrupt
trigger
A comparator is configured through two status/control registers,
Analog Comparator Control
(ACCTL)
and
Analog Comparator Status (ACSTAT)
. The internal reference is configured through
one control register,
Analog Comparator Reference Voltage Control (ACREFCTL)
. Interrupt
status and control are configured through three registers,
Analog Comparator Masked Interrupt
Status (ACMIS)
,
Analog Comparator Raw Interrupt Status (ACRIS)
, and
Analog Comparator
Interrupt Enable (ACINTEN)
.
Typically, the comparator output is used internally to generate an interrupt as controlled by the
ISEN
bit in the
ACCTL
register. The output may also be used to drive one of the external pins (
Cno
), or
generate an analog-to-digital converter (ADC) trigger.
1655
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller