== My computer has extra LEDs for wireless information, how can I make them work? ==

If the LED is connected to the chipsets GPIO pins, then the following commands should make it blink slowly on power up, and then switch to a 3 second blink period on association (similar to the LED behaviour on PC Cards).

Use:
{{{
sysctl -w dev.wifi0.ledpin=1
sysctl -w dev.wifi0.softled=1
}}}
For AR5007EG the value of dev.wifi0.ledpin must be 3

  For MadWifi-Old use:
  {{{
  sysctl -w dev.ath0.ledpin=1
  sysctl -w dev.ath0.softled=1
  }}}


Note that sysctl parameters are not saved in non-volatile memory, so you’ll want to put these commands in a local boot script or just add the following lines to {{{/etc/sysctl.conf}}}:

{{{
dev.wifi0.ledpin=1
dev.wifi0.softled=1
}}}

  For MadWifi-Old use:
  {{{
  dev.ath0.ledpin=1
  dev.ath0.softled=1
  }}}

For the owners of Gigabyte GN-WIAG02 minipci card: I found out that the led is on pin 2, so in this case dev.wifi0.ledpin=2 is the proper choice. Note that I am using it with Dell D610 laptop, this could also be important.

For the owners of IBM Thinkpads (at least R51 and R51e series): the following settings will light up your led:
{{{
sysctl -w dev.wifi0.ledpin=0
sysctl -w dev.wifi0.softled=1
}}} 
For the Thinkpad R60e and X40 set both values to 1.

== Can I turn on my wireless card LEDs automatically? ==

If you were able to turn on your LEDs as described above, then most likely yes.

=== Using udev ===

[http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html udev] ''"works entirely in userspace, using hotplug events the kernel sends whenever a device is added or removed from the kernel."'' udev can also ''"run a particular program when a device is connected or disconnected."''

To make udev enable the LEDs, create a short script that calls the correct sysctl commands and then add a [http://www.reactivated.net/writing_udev_rules.html udev rule]: `KERNEL=="ath0", RUN+="/path/to/led/script"`

To see if udev manages your wireless card, try '''`$ udevinfo -a -p /sys/class/net/ath0`''' and if you see descriptions about your card fill the screen, then udev manages your wireless card.

==== Working example ====

The PCMCIA wireless card [wiki:BigOldCompatibilityList#SMCWCBTG/SMCWCBTGEU SMC WCBT-G] has two LEDs: one for Link (which lights when the card is up) and the other for Activity (which blinks with traffic). Both LEDs can be turned on using the following script:

{{{
#!/bin/bash
# Set the Link LED to behave like link.
sysctl -w dev.wifi0.ledpin=1
sysctl -w dev.wifi0.softled=1
sysctl -w dev.wifi0.softled=0

# Set the Activity LED to behave like activity.
sysctl -w dev.wifi0.ledpin=0
sysctl -w dev.wifi0.softled=1
}}}

 * Save this script as "`leds`"
 * Make it executable with '''`$ chmod +x leds`'''
 * Place it in your system path with something like '''`# mv leds /usr/local/bin`'''
 * Add a udev rule to '''`/etc/udev/udev.d/10-local.rules`'''
 `KERNEL=="ath0", RUN+="/usr/local/bin/leds"`
 * Reload udev's rules with '''`# udevcontrol reload_rules`'''
 * Test your new rule with '''`$ udevtest /class/net/ath0`'''
  {{{
$ udevtest /sys/class/net/ath0
This program is for debugging only, it does not create any node,
or run any program specified by a RUN key. It may show incorrect results,
if rules match against subsystem specfic kernel event variables.

main: looking at device '/class/net/ath0' from subsystem 'net'
wait_for_sysfs: file '/sys/class/net/ath0/address' appeared after 0 loops
udev_rules_get_name: rule applied, 'ath0' becomes 'ath0'
main: run: 'ifplugd.agent'
main: run: '/usr/local/bin/leds'
main: run: 'socket:/org/kernel/udev/monitor'
main: run: 'net.agent'
main: run: 'socket:/org/freedesktop/hal/udev_event'
  }}}

The next time udev dectects the wireless card being connected to the system, it will call `/usr/local/bin/leds` and the LEDs will turn on. Anytime you want to turn on the LEDs, you can also issue '''`# leds`'''.

==== Working example for a Philips SNN6500 PCMCIA card on Gentoo ====

See http://dev.gentoo.org/~wschlich/misc/scripts/udev/atheros-wlan-card-led-activation/ath_led.sh