With all of the changes in the kernels lately, I wanted to add a "heartbeat" LED to gpio7 on my rpi B rev2.
I uncommented as follows in /boot/config.txt:
$this->bbcode_second_pass_code('', '$ cat /boot/config.txt | grep act_led
# act_led_trigger Choose which activity the LED tracks.
# act_led_activelow Set to "on" to invert the sense of the LED
# act_led_gpio Set which GPIO pin to use for the activity LED
#device_tree_param=act_led_trigger=mmc
device_tree_param=act_led_trigger=heartbeat
#device_tree_param=act_led_activelow=on
device_tree_param=act_led_gpio=7
')
When I rebooted, my new LED did not come on. When I looked at led0 in /sys/class its trigger was set to [none]:
$this->bbcode_second_pass_code('', '$ cat /sys/class/leds/led0/trigger
[none] usb-gadget usb-host mmc0 cpu0 input
')
So then I did modprobe:
$this->bbcode_second_pass_code('', '$ sudo modprobe ledtrig_heartbeat
')
Now when I look at led0 in /sys/class I get:
$this->bbcode_second_pass_code('', '$ cat /sys/class/leds/led0/trigger
none usb-gadget usb-host mmc0 cpu0 input [heartbeat]
')
And my new LED on gpio7 has a hearbeat.
The question is why do I have to run modprobe to get the led0 to have a hearbeat when I have set up for it in /boot/config.txt?
The original Arch Linux installation was from the disk image of 2014-06 which has been updated all the way along since then. Is there something missing that I can add or do I have to start from scratch?
Thanks,
Paul Crawford