General Purpose Input/Output
From Embedded Xinu
(Redirected from GPIO)
General Purpose Input and Output is a simple method of communication. Currently the shell implements the led and gpiostat commands to use these ports.
|GPIO 0||WLAN LED|
|GPIO 1||Power LED|
|GPIO 2||Cisco LED White|
|GPIO 3||Cisco LED Orange|
|GPIO 4||Cisco Button|
|GPIO 6||Reset Button|
|GPIO 7||DMZ LED|
There are four control and status registers, each which is 2 bytes.
- Input (0xb8000060) - If a GPIO pin is set for output, its input bit is automatically set to 0.
- Output (0xb8000064) - If a GPIO pin is set for input, its output bit is automatically set to 0.
- Enable (0xb8000068) - Determines if a GPIO pin is used for input or output. A bit value of 0 is input and 1 is output.
- Control (0xb800006c) - Usage is currently unknown.
- An LED is enabled by setting its enable bit to 1.
- When an LED is enabled, its input bit becomes 0.
- Once an LED is enabled, if its output bit is 0, the LED is on and if its output bit is 1, the LED is off.