Difference between revisions of "General Purpose Input/Output"

From Embedded Xinu
Jump to navigation Jump to search
Line 11: Line 11:
 
| GPIO 3 || Cisco LED Orange
 
| GPIO 3 || Cisco LED Orange
 
|-
 
|-
| GPIO 4 || ''Front Button?''
+
| GPIO 4 || Cisco Button
 
|-
 
|-
 
| GPIO 5 || ''Unkown''
 
| GPIO 5 || ''Unkown''
 
|-
 
|-
| GPIO 6 || ''Reset Button?''
+
| GPIO 6 || Reset Button
 
|-
 
|-
 
| GPIO 7 || DMZ LED
 
| 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 ==
 
== LEDs ==
 
Research Notes:
 
Research Notes:
 +
* An LED is enabled by setting its enable bit to 1.
 
* When an LED is enabled, its input bit becomes 0.
 
* 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.
 
* 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.

Revision as of 18:08, 26 June 2007

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