RetroPie: Xbox wireless controller setup on Raspberry Pi

This shows how to get your Xbox wireless controller up and running in RetroPie and the RetroArch emulator on the Raspberry Pi.

Here is the wireless receiver I used, about £4 on eBay:
http://images.doba.com/products/3400/media_catalog_product_1_0_10200304_1_10.jpg

I used an official Xbox 360 wireless controller:
http://img4.wikia.nocookie.net/__cb20140223095002/thegameroom/images/e/e3/Xbox_360_Controller.jpg

The "pair/sync" button is here:
http://compass.xboxlive.com/assets/bd/57/bd57d49b-fdad-483d-9dde-7c39e4f83d00.png?n=one-controller-wireless-sync-m.png

Install instructions I followed:
https://github.com/petrockblog/RetroPie-Setup/wiki/Setting-up-the-XBox360-controller

This thread is also useful:
http://blog.petrockblock.com/forums/topic/xbox-360-blinking-lights/