Hi @beckmx,
Using GPIO and turning on/off LED from the dragonboard, using Debian is probably is the easiest way.
Follow the instruction of installing Debian.
Then install libsoc and 96BoardsGPIO.
“libsoc”
$ sudo apt-get update
$ sudo apt-get install build-essential autoconf libtool libsoc-dev
“96BoardsGPIO”
$ git clone https://github.com/96Boards/96BoardsGPIO.git
$ cd 96BoardsGPIO
./autogen.sh
$ ./configure
$ make
$ sudo make install
Then connect Grove LED module or something similar to GPIO-A on LS-connector.
$ export GPIO_A=36
$ cd /sys/class/gpio
$ echo $GPIO_A | sudo tee export # GPIO_A is 488 on HiKey, 36 on DragonBoard
$ cd gpio$GPIO_A
$ echo out | sudo tee direction
$ echo 1 | sudo tee value # Turn LED on
$ echo 0 | sudo tee value # Turn LED off
I am not sure the 36 is the right number for GPIO_A, so if the LED does not go on and off, try looking the directry of /sys/class/gpio for appropriate number.