LM3S2793 Datasheet, PDF (1023/1194 Pages) Texas Instruments – Stellaris® LM3S2793 Microcontroller

Stellaris^® LM3S2793 Microcontroller
Figure 21-1. QEI Block Diagram
Control & Status
QEICTL
QEISTAT
QEILOAD
Velocity Timer
QEITIME
PhA
PhB
IDX
Velocity
Predivider
clk
Quadrature
Encoder dir
Velocity Accumulator
QEICOUNT
QEISPEED
QEIMAXPOS
Position Integrator
QEIPOS
QEIINTEN
Interrupt Control
QEIRIS
QEIISC
Interrupt
21.2
Signal Description
The following table lists the external signals of the QEI module and describes the function of each.
The QEI 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 these QEI signals. The AFSEL bit in the GPIO Alternate Function Select
(GPIOAFSEL) register (page 441) should be set to choose the QEI function. The number in
parentheses is the encoding that must be programmed into the PMCn field in the GPIO Port Control
(GPIOPCTL) register (page 459) to assign the QEI signal to the specified GPIO port pin. For more
information on configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 417.
Table 21-1. QEI Signals (100LQFP)
Pin Name
IDX0
IDX1
PhA0
PhA1
Pin Number Pin Mux / Pin
Assignment
10
PD0 (3)
40
PG5 (4)
72
PB2 (2)
90
PB6 (5)
92
PB4 (6)
100
PD7 (1)
17
PG2 (8)
61
PF1 (2)
84
PH2 (1)
11
PD1 (3)
25
PC4 (2)
43
PF6 (4)
95
PE2 (4)
37
PG6 (1)
96
PE3 (3)
Pin Type
I
I
I
I
Buffer Type^a Description
TTL
QEI module 0 index.
TTL
QEI module 1 index.
TTL
QEI module 0 phase A.
TTL
QEI module 1 phase A.
January 20, 2012
Texas Instruments-Production Data
1023