LM3S1G21 Datasheet, PDF (410/955 Pages) Texas Instruments – Stellaris® LM3S1G21 Microcontroller

General-Purpose Input/Outputs (GPIOs)
■ GPIO Port C (APB): 0x4000.6000
■ GPIO Port C (AHB): 0x4005.A000
■ GPIO Port D (APB): 0x4000.7000
■ GPIO Port D (AHB): 0x4005.B000
■ GPIO Port E (APB): 0x4002.4000
■ GPIO Port E (AHB): 0x4005.C000
■ GPIO Port F (APB): 0x4002.5000
■ GPIO Port F (AHB): 0x4005.D000
■ GPIO Port G (APB): 0x4002.6000
■ GPIO Port G (AHB): 0x4005.E000
■ GPIO Port H (APB): 0x4002.7000
■ GPIO Port H (AHB): 0x4005.F000
■ GPIO Port J (APB): 0x4003.D000
■ GPIO Port J (AHB): 0x4006.0000
Note that each GPIO module clock must be enabled before the registers can be programmed (see
page 254). There must be a delay of 3 system clocks after the GPIO module clock is enabled before
any GPIO module registers are accessed.
Important: All GPIO pins are configured as GPIOs and tri-stated by default (GPIOAFSEL=0,
GPIODEN=0, GPIOPDR=0, GPIOPUR=0, and GPIOPCTL=0, with the exception of the
pins shown in the table below. A Power-On-Reset (POR) or asserting RST puts the pins
back to their default state.
Table 9-6. GPIO Pins With Non-Zero Reset Values
GPIO Pins
PA[1:0]
PA[5:2]
PB[3:2]
PC[3:0]
Default State
UART0
SSI0
I²C0
JTAG/SWD
GPIOAFSEL GPIODEN GPIOPDR GPIOPUR
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
GPIOPCTL
0x1
0x2
0x3
0x1
The default register type for the GPIOCR register is RO for all GPIO pins with the exception of the
NMI pin and the four JTAG/SWD pins (PB7 and PC[3:0]). These five pins are the only GPIOs that
are protected by the GPIOCR register. Because of this, the register type for GPIO Port B7 and GPIO
Port C[3:0] is R/W.
The default reset value for the GPIOCR register is 0x0000.00FF for all GPIO pins, with the exception
of the NMI pin and the four JTAG/SWD pins (PB7 and PC[3:0]). To ensure that the JTAG port is
not accidentally programmed as GPIO pins, the PC[3:0] pins default to non-committable. Similarly,
to ensure that the NMI pin is not accidentally programmed as a GPIO pin, the PB7 pin defaults to
non-committable. Because of this, the default reset value of GPIOCR for GPIO Port B is 0x0000.007F
while the default reset value of GPIOCR for Port C is 0x0000.00F0.
Table 9-7. GPIO Register Map
Offset Name
Type
0x000 GPIODATA
R/W
0x400 GPIODIR
R/W
0x404 GPIOIS
R/W
Reset
0x0000.0000
0x0000.0000
0x0000.0000
Description
GPIO Data
GPIO Direction
GPIO Interrupt Sense
See
page
413
414
415
410
January 22, 2012
Texas Instruments-Production Data