LM3S6753 Datasheet, PDF (184/625 Pages) Texas Instruments – Stellaris LM3S6753 Microcontroller

General-Purpose Input/Outputs (GPIOs)
Table 9-2. GPIO Interrupt Configuration Example (continued)
Register
GPIOIBE
Desired
Interrupt
Event
Trigger
0=single
edge
Pin 2 Bit Value^a
7
6
X
X
5
X
4
X
3
X
1=both
edges
GPIOIEV 0=Low level,
X
X
X
X
X
or negative
edge
1=High level,
or positive
edge
GPIOIM
0=masked
0
0
0
0
0
1=not
masked
a. X=Ignored (don’t care bit)
2
0
1
1
1
X
X
0
0
X
X
0
9.3 Register Map
Table 9-3 on page 185 lists the GPIO registers. The offset listed is a hexadecimal increment to the
register’s address, relative to that GPIO port’s base address:
■ GPIO Port A: 0x4000.4000
■ GPIO Port B: 0x4000.5000
■ GPIO Port C: 0x4000.6000
■ GPIO Port D: 0x4000.7000
■ GPIO Port E: 0x4002.4000
■ GPIO Port F: 0x4002.5000
■ GPIO Port G: 0x4002.6000
Important: The GPIO registers in this chapter are duplicated in each GPIO block; however,
depending on the block, all eight bits may not be connected to a GPIO pad. In those
cases, writing to those unconnected bits has no effect, and reading those unconnected
bits returns no meaningful data.
Note:
The default reset value for the GPIOAFSEL, GPIOPUR, and GPIODEN registers are
0x0000.0000 for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and
PC[3:0]). These five pins default to JTAG/SWD functionality. Because of this, the default
reset value of these registers for GPIO Port B is 0x0000.0080 while the default reset value
for Port C is 0x0000.000F.
The default register type for the GPIOCR register is RO for all GPIO pins with the exception
of the five JTAG/SWD pins (PB7 and PC[3:0]). These five pins are currently 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 five JTAG/SWD pins (PB7 and PC[3:0]). To ensure that the JTAG port
is not accidentally programmed as a GPIO, these five pins default to non-committable.
184
April 05, 2010
Texas Instruments-Production Data