General Purpose Input/Output

From Embedded Xinu
(Redirected from GPIO)
Jump to: navigation, search

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.

Resources

Personal tools
Namespaces

Variants
Actions
Navigation
Toolbox