LM3S5G31 Datasheet, PDF (1053/1223 Pages) Texas Instruments – Stellaris LM3S5G31 Microcontroller

Stellaris^® LM3S5G31 Microcontroller
Table 21-1. QEI Signals (100LQFP) (continued)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
PhB0
22
PC7 (2)
I
23
PC6 (2)
42
PF7 (4)
47
PF0 (2)
83
PH3 (1)
96
PE3 (4)
TTL
QEI module 0 phase B.
PhB1
11
PD1 (11)
I
36
PG7 (1)
95
PE2 (3)
TTL
QEI module 1 phase B.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
Table 21-2. QEI Signals (108BGA)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
IDX0
G1
PD0 (3)
I
M7
PG5 (4)
A11
PB2 (2)
A7
PB6 (5)
A6
PB4 (6)
A2
PD7 (1)
TTL
QEI module 0 index.
IDX1
J1
PG2 (8)
I
H12
PF1 (2)
D11
PH2 (1)
TTL
QEI module 1 index.
PhA0
G2
PD1 (3)
I
L1
PC4 (2)
M8
PF6 (4)
A4
PE2 (4)
TTL
QEI module 0 phase A.
PhA1
L7
PG6 (1)
I
B4
PE3 (3)
TTL
QEI module 1 phase A.
PhB0
L2
PC7 (2)
I
M2
PC6 (2)
K4
PF7 (4)
M9
PF0 (2)
D10
PH3 (1)
B4
PE3 (4)
TTL
QEI module 0 phase B.
PhB1
G2
PD1 (11)
I
C10
PG7 (1)
A4
PE2 (3)
TTL
QEI module 1 phase B.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
21.3
Functional Description
The QEI module interprets the two-bit gray code produced by a quadrature encoder wheel to integrate
position over time and determine direction of rotation. In addition, it can capture a running estimate
of the velocity of the encoder wheel.
The position integrator and velocity capture can be independently enabled, though the position
integrator must be enabled before the velocity capture can be enabled. The two phase signals, PhA
and PhB, can be swapped before being interpreted by the QEI module to change the meaning of
forward and backward and to correct for miswiring of the system. Alternatively, the phase signals
can be interpreted as a clock and direction signal as output by some encoders.
July 03, 2014
Texas Instruments-Production Data
1053