Add readme

README.md

@@ -1,17 +1,49 @@
 # OctoPrint-Awesome-Karmen-LED
 
-**TODO:** Describe what your plugin does.
+Control APA102 LEDs attached to Raspberry Pi.
 
-## Setup
+## Requirements
 
-Install via the bundled [Plugin Manager](https://docs.octoprint.org/en/master/bundledplugins/pluginmanager.html)
+- Raspberry pi with octoprint
+- APA102 LED attached to rpi
+
+## Wiring
+
+- rpi is 3.3v and APA102 is 5v device. Correct solution would be usage of level shifter as described [here](https://github.com/tinue/apa102-pi#wiring). But from our experience it works just fine without level shifting.
+
+### Connect
+
+- LED 5v <-> rpi 5v (in case of just one or two leds; longer strip needs separate power source or it may end up with demaged rpi)
+- LED ground <-> rpi ground
+- LED data <-> rpi SPI MOSI
+- LED clock <-> rpi SPI SCLK
+
+## Installation
+
+- Install via the bundled [Plugin Manager](https://docs.octoprint.org/en/master/bundledplugins/pluginmanager.html)
 or manually using this URL:
 
     https://github.com/fragaria/karmen-led-octoprint-plugin/archive/master.zip
 
-**TODO:** Describe how to install your plugin, if more needs to be done than just installing it via pip or through
-the plugin manager.
+- Enable SPI interface on RPI [(official documentation)](https://www.raspberrypi-spy.co.uk/2014/08/enabling-the-spi-interface-on-the-raspberry-pi/)
+  - On desktop use "Raspberry Pi Configuration" dialog *or*
+  - From terminal run `sudo raspi-config` and in `Interfacing options` enable `P4 SPI` *or*
+  - Edit `sudo nano /boot/config.txt` and uncomment `dtparam=spi=on` line.
+
+## Usage
+
+Plugin has two modes of operation - API and automatic. Modes can be switched in plugin's settings.
+
+### API mode
+
+To turn LEDs on send POST request to `/api/plugin/awesome_karmen_led` with json body `{"command": "set_led", "color":[<R>, <G>, <B>]}` where `<R>`,`<G>` and `<B>` are numbers from 0 to 255.
+
+Example:
+
+``` bash
+curl http://<rpi_hostname_or_ip>/api/plugin/awesome_karmen_led --header "X-Api-Key: <YOURAPIKEY>" -X POST -d '{"command": "set_led", "color":[255, 255, 255]}' -H "Content-Type: application/json"
+```
 
-## Configuration
+### Auto mode
 
-**TODO:** Describe your plugin's configuration options (if any).
+Colors are changed automaticaly by connection and print events.