LM3S1621 Datasheet, PDF (402/947 Pages) Texas Instruments – ARM and Thumb are registered trademarks and Cortex is a trademark

General-Purpose Input/Outputs (GPIOs)
Figure 9-2. Analog/Digital I/O Pads
Port
Control
GPIOPCTL
Commit
Control
GPIOLOCK
GPIOCR
Mode
Control
GPIOAFSEL
Periph 0
Periph 1
Periph n
Alternate Input
Alternate Output
Alternate Output Enable
Data
Control
GPIODATA
GPIODIR
GPIO Input
GPIO Output
GPIO Output Enable
Pad Input
Pad Output
Analog/Digital
I/O Pad
Pad Output Enable
Interrupt
Interrupt
Control
GPIOIS
GPIOIBE
GPIOIEV
GPIOIM
GPIORIS
GPIOMIS
GPIOICR
Pad
Control
GPIODR2R
GPIODR4R
GPIODR8R
GPIOSLR
GPIOPUR
GPIOPDR
GPIOODR
GPIODEN
GPIOAMSEL
Identification Registers
GPIOPeriphID0
GPIOPeriphID1
GPIOPeriphID2
GPIOPeriphID3
GPIOPeriphID4
GPIOPeriphID5
GPIOPeriphID6
GPIOPeriphID7
GPIOPCellID0
GPIOPCellID1
GPIOPCellID2
GPIOPCellID3
Analog Circuitry
ADC
(for GPIO pins that
connect to the ADC
input MUX)
Isolation
Circuit
Package I/O Pin
9.2.1
9.2.1.1
Data Control
The data control registers allow software to configure the operational modes of the GPIOs. The data
direction register configures the GPIO as an input or an output while the data register either captures
incoming data or drives it out to the pads.
Caution – It is possible to create a software sequence that prevents the debugger from connecting to
the Stellaris^® microcontroller. If the program code loaded into flash immediately changes the JTAG
pins to their GPIO functionality, the debugger may not have enough time to connect and halt the
controller before the JTAG pin functionality switches. As a result, the debugger may be locked out of
the part. This issue can be avoided with a software routine that restores JTAG functionality based on
an external or software trigger.
Data Direction Operation
The GPIO Direction (GPIODIR) register (see page 411) is used to configure each individual pin as
an input or output. When the data direction bit is cleared, the GPIO is configured as an input, and
the corresponding data register bit captures and stores the value on the GPIO port. When the data
direction bit is set, the GPIO is configured as an output, and the corresponding data register bit is
driven out on the GPIO port.
402
January 21, 2012
Texas Instruments-Production Data