excellent resource.
[General information about IR](https://www.sbprojects.net/knowledge/ir/)
+Also [IRMP](https://www.mikrocontroller.net/articles/IRMP_-_english)
+
The NEC protocol:
[altium](http://techdocs.altium.com/display/FPGA/NEC+Infrared+Transmission+Protocol)
[circuitvalley](http://www.circuitvalley.com/2013/09/nec-protocol-ir-infrared-remote-control.html)