LM3S316 Luminary Micro, Inc., LM3S316 Datasheet - Page 119

• Manufacturer Part Number: LM3S316
• Description: Microcontroller
• Manufacturer: Luminary Micro, Inc.

Figure 8-2. GPIO Port Block Diagram
8.2.1
April 27, 2007
Alternate Input
Alternate Output
Alternate Output Enable
Interrupt
Each GPIO port is a separate hardware instantiation of the same physical block (see Figure 8-2).
The LM3S316 microcontroller contains five ports and thus five of these physical GPIO blocks.
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 125) 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.
GPIOAFSEL
GPIOPeriphID0
GPIOPeriphID1
GPIOPeriphID2
GPIOPeriphID3
GPIODATA
Selection
Function
GPIODIR
GPIOMIS
GPIOICR
Interrupt
GPIOIBE
GPIOIEV
GPIORIS
Control
GPIOIM
GPIOIS
Data
I/O
Identification Registers
GPIOPeriphID4
GPIOPeriphID5
GPIOPeriphID6
GPIOPeriphID7
GPIO Input
GPIO Output
GPIO Output Enable
GPIODR2R
GPIODR4R
GPIODR8R
GPIOODR
GPIOPUR
GPIOPDR
GPIODEN
GPIOSLR
Control
I/O Pad
GPIOPCellID0
GPIOPCellID1
GPIOPCellID2
GPIOPCellID3
D
M
U
M
U
M
U
E
X
X
X
Preliminary
Pad Input
Pad Output
Pad Output Enable
Pad
I/O
LM3S316 Data Sheet
Package I/O Pin
119