Here's some code I mashed up from ZXing and BarcodeEye. You should be able to drop this into your code and have a relatively simple QR Code scan activity, for reading in data, etc.
The MainActivity is an example of how it works.
If you have any questions, let me know!
Released under Apache 2 and all credit for the code goes to the original authors, namely the ZXing team and BarcodeEye.