no heartbeat trigger on act_led

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no heartbeat trigger on act_led

Postby paulcrawford » Fri Feb 20, 2015 3:29 am

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
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Posts: 20
Joined: Sat Jan 25, 2014 1:16 am

Re: no heartbeat trigger on act_led

Postby moonman » Fri Feb 20, 2015 4:30 am

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Re: no heartbeat trigger on act_led

Postby paulcrawford » Fri Feb 20, 2015 11:57 am

Thanks moonman, as usual.

I put it into raspberrypi.conf:

$this->bbcode_second_pass_code('', '$ cat /etc/modules-load.d/raspberrypi.conf
bcm2708-rng
snd-bcm2835
ledtrig_heartbeat
')

And that works perfectly. What I don't understand is why it was not there already and there was no indication in the newly released config.txt file that it was necessary to put the module there to actually get a heartbeat on led0?

Paul Crawford
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Posts: 20
Joined: Sat Jan 25, 2014 1:16 am


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