These are various hacked-up projects that use the pipe- fifo LED protocol as part of arcan >= 0.5.2.

g810 - GPLv3, see README.md and LICENSE file. Adds support for reading protocol controls via stdin.

arduino - arduino project and makefiles for programming an arduino device to use the protocol over a serial or i2c connection in order to control PWM adafruit neopixel- LEDs.

testgen - simple stress-test to randomly flash lights,
          make and run like ./test | g810-led --aled -

fifos can be configured via:

mkfifo /path/to/fifo
mkfifo /path/to/fifo2

and so on.

to tell arcan about the presence of the LED devices (scanned on startup):

arcan_db add_appl_kv arcan ext_led /path/to/fifo
arcan_db add_appl_kv arcan ext_led_2 /path/to/fifo2

for the arduino setup, the USB- serial port can be configured like:

stty -F /dev/ttyACM0 cs8 9600 ignbrk -brkint -imaxbel -opost
	 -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl
	 -echoke noflsh -ixon -crtscts

and then fed like:

cat /path/to/fifo > /dev/ttyACM0

the g810 module, similarly:

cat /path/to/fifo | g810-led --arcan-stdin

Each packet is a 2-byte tuple of opcode and argument.

first byte is one of (ascii) 'A' 'a' 'r' 'g' 'b' 'i' 'c' or 'o'.

'A' [ign] : set active LED index to 'all'
'a' [num] : set active LED index to [num] (special, 255 - is ignored)
'r' [num] : set current Red value to [num]
'g' [num] : set current Green value to [num]
'b' [num] : set current Blue value to [num]
'i' [num] : set all (Red, Green, Blue) value to [num]
'c' [num] : num = 0, commit - no buffer, > 0 - buffer
'o' [ign] : disconnects

with the buffer indication meaning that more values are to come before any update to led devices should be pushed.

The arcan scripts can then use set_led_rgb(dev, ind, r, g, b, buf) calls to emit data to the respective devices. Advanced such use can be found in durden iostatem.lua + devmaps/led/...

devmaps/ contain example such devmaps for the setup shown above. A video of its use can be found at gfycat