LM3S317 Datasheet, PDF (116/379 Pages) List of Unclassifed Manufacturers – Microcontroller

General-Purpose Input/Outputs (GPIOs)
Figure 8-2. GPIO Port Block Diagram
Function
Selection
GPIOAFSEL
Alternate Input
Alternate Output
Alternate Output Enable
D
E
M
Pad Input
U
X
I/O
GPIO Input
M
U
Pad Output
X
I/O
Pad
Data
GPIO Output
GPIODATA
GPIODIR
GPIO Output Enable
M
U
Pad Output Enable
X
Interrupt
Interrupt
Control
GPIOIS
GPIOIBE
GPIOIEV
GPIOIM
GPIORIS
GPIOMIS
GPIOICR
I/O Pad
Control
GPIODR2R
GPIODR4R
GPIODR8R
GPIOSLR
GPIOPUR
GPIOPDR
GPIOODR
GPIODEN
Package I/O Pin
8.2.1
Identification Registers
GPIOPeriphID0
GPIOPeriphID1
GPIOPeriphID2
GPIOPeriphID3
GPIOPeriphID4
GPIOPeriphID5
GPIOPeriphID6
GPIOPeriphID7
GPIOPCellID0
GPIOPCellID1
GPIOPCellID2
GPIOPCellID3
Data Register Operation
To aid in the efficiency of software, the GPIO ports allow for the modification of individual bits in the
GPIO Data (GPIODATA) register (see page 122) by using bits [9:2] of the address bus as a mask.
This allows software drivers to modify individual GPIO pins in a single instruction, without affecting
the state of the other pins. This is in contrast to the "typical" method of doing a read-modify-write
operation to set or clear an individual GPIO pin. To accommodate this feature, the GPIODATA
register covers 256 locations in the memory map.
During a write, if the address bit associated with that data bit is set to 1, the value of the
GPIODATA register is altered. If it is cleared to 0, it is left unchanged.
For example, writing a value of 0xEB to the address GPIODATA + 0x098 would yield as shown in
Figure 8-3, where u is data unchanged by the write.
116
May 4, 2007
Preliminary