LED

The linux LED driver class

On recent kernel, linux have a led driver. This led can be driven from /sys/class/leds/ directory.

For APF28Dev, the led is configurable under the directory :

 # cd /sys/class/leds/apfdev:green:user

Blinking

The blinking style can be selected with trigger file. By defaut on APF28Dev, Heartbeat is selected :

# cat /sys/class/leds/apfdev:green:user/trigger 
none nand-disk mmc0 timer [heartbeat] backlight gpio default-on 

Blinking style can be changed with echo command :

# echo "nand-disk" > /sys/class/leds/apfdev:green:user/trigger
# cat /sys/class/leds/apfdev:green:user/trigger
none [nand-disk] mmc0 timer heartbeat backlight gpio default-on 

With this "nand-disk" option selected, the led will blink each time nand access occur (try with sync command to see it blinking).

Links

See the kernel documentation Documentation/leds-class.txt for more information about this driver.