LM3S1637 Datasheet, PDF (293/696 Pages) Texas Instruments – ARM and Thumb are registered trademarks and Cortex is a trademark

Stellaris^® LM3S1637 Microcontroller
Table 8-7. GPIO Interrupt Configuration Example (continued)
Desired
Pin 2 Bit Value^a
Register
Interrupt
Event
7
6
5
4
3
Trigger
GPIOIBE
0=single
X
X
X
X
X
edge
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
8.4 Register Map
Table 8-8 on page 294 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
■ GPIO Port H: 0x4002.7000
Note that the GPIO module clock must be enabled before the registers can be programmed (see
page 226). There must be a delay of 3 system clocks after the GPIO module clock is enabled before
any GPIO module registers are accessed.
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.
June 18, 2012
293
Texas Instruments-Production Data