General Purpose Input/Output
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General Purpose Input and Output is a simple method of communication. Currently the shell implements the led and gpiostat commands to use these ports.
Contents
Port Assignments
| Pin | Assignment |
|---|---|
| GPIO 0 | WLAN LED |
| GPIO 1 | Power LED |
| GPIO 2 | Cisco LED White |
| GPIO 3 | Cisco LED Orange |
| GPIO 4 | Cisco Button |
| GPIO 5 | Unkown |
| GPIO 6 | Reset Button |
| GPIO 7 | DMZ LED |
Registers
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.
LEDs
Research Notes:
- 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.
