Last year, we used this sensor and it worked reliably. To wire it, we used a low pass filter to average the PWM signal. There are instructions to build the filter on page 18 of the datasheet here:
http://ams.com/eng/Products/Position...ensors/AS5145B
Do note that when used in this way, the sensor outputs a value proportional to it's absolute position, so it can be used like a potentiometer. For us this was perfect as we were not counting number of rotations, but rather what angle the shaft was within a rotation.
The pinouts are on page 4. +5v is pin 16, and Gnd is pin 7. We wired these to the digital sidecar last year, but I think you can wire them right to the DIO on the RoboRio.