Just out of curiosity, why isn’t the ADC used for obtaining values for the line sensor? Is there a specific reason or is it just a carry over from using devices with no ADC?
Which line sensor are you referring to? In general, our Zumo and 3pi use the QTR-1RC sensors, and they use the time it takes to discharge the capacitor on the sensor to measure the reflectance. We find the RC version generally performs better than the analog version, and that there is no need to read the RC version of the sensor with the ADC because the time of the pulse is already an analog representation of the reflectance.