Cool project, I did something very similar as well!
There is software on there too that you are free to reference. It works with some exceptions. The method that I used for commutation is bemf integration similar to the ti instaspin approach. The issues that I had was that for very fast motors(>500Kv), I wasn't sampling the ADC fast enough to get the commutation timing right but for slow motors, it works great.
A few words of wisdom since I worked on this project for quite some time. I would recommend using the 28pin Tssop or qfn32 versions of g2553. Reason being is that it has 3 pins attached to ta1.1 which you can use for the high side pwm signals and 3 pins attached to ta1.2 to be used for low side pwm signals. This does 3 things, frees up timer 0 for something else, allows you to do dead time insertion (if your gate drivers don't already) and just makes your code easier too!
The other thing is that you will see your pwm super imposed on your bemf which will likely cause false trips of the comparator. To solve this, there's a low pass filter but that also introduces a dc offset that throws off your zero cross point.
Long story short, I came up with a different network that filters and then ac couples the bemf to the comparator. I was seeing pretty good results with that approach. Then I had to return my borrowed scope and have not been able to work on it. Good news is I'm getting a brand new Rigol DS2072 for keeps on Thursday.
Anyway I guess that is my project life story, hope it helps. Tomorrow ill try to dig up schematics with those improvements (not in github yet).
Btw the schematics are very inspired by the microkoptor.de schematics, mine are as well... I wonder how they got away with the pwm glitches in their software. Obviously theirs works quite well.