Add readme

readme.md

@@ -0,0 +1,42 @@
+# WS2812Serial - Non-Blocking WS2812B / NeoPixel LEDs Library
+
+Similar to [OctoWS2811](https://www.pjrc.com/teensy/td_libs_OctoWS2811.html), this library
+allows you to use WS2811, WS2812, WS2812B / NeoPixel LEDs without blocking interrupts.
+
+![](ws2812serial.jpg)
+
+Non-blocking allows other libraries, especially
+[Audio](https://www.pjrc.com/teensy/td_libs_Audio.html) and high speed serial communication
+to function properly while the LEDs update.  Complex animation can also run faster,
+because the show() function does not wait for the LEDs to update, allowing your code
+more time to draw the next frame.
+
+## Hardware Resources Used
+
+WS2812Serial controls a single LED strip, using only 1 pin.  While any number of
+LEDs may be connected, in practice 1 pin is best for small projects with less
+than 500 to 1000 LEDs.  OctoWS2811 offers 8 parallel outputs for large projects.
+
+Non-blocking performance does come with a cost.  15 bytes of memory are required
+per LED, rather than the usual 3 bytes with [FastLED](http://fastled.io/) or
+[Adafruit NeoPixel](https://github.com/adafruit/Adafruit_NeoPixel).  One of
+the [hardware serial ports](https://www.pjrc.com/teensy/td_uart.html) is also
+used to transmit the data, making that port unavailable for other uses.
+
+## Supported Pins & Serial Ports
+
+| Port    | Teensy LC   | Teensy 3.2 | Teensy 3.5 | Teensy 3.6 |
+| :------ | :---------: | :--------: | :--------: | :--------: |
+| Serial1 | 1, 4, 5, 24 | 1, 5       | 1, 5, 26   | 1, 5, 26   |
+| Serial2 |             | 10, 31     | 10         | 10         |
+| Serial3 |             | 8, 20      | 8, 20      | 8, 20      |
+| Serial4 |             |            | 32         | 32         |
+| Serial5 |             |            | 33         | 33         |
+| Serial6 |             |            | 48         |            |
+
+Serial2 & Serial3 on Teensy LC are not supported, due to lack of configurable
+oversampling needed to run at the high speed required.
+
+Serial6 on Teensy 3.6 is not currently supported, due to different hardware
+registers.
+