PID encoders vs hall sensors

Ive been reading about pid and it says for gearbox control you can either use encoders or hall sensors (gear tooth sensor)

The advantage about a quad encoder is you can know which direction your gear box is going. A hall effect sensor can work quite well, but it will not give you direction. The encoder will also give more pulses per revolution.

For speed, i am not sure that it matters. For position a quad encoder would be better

The first Gear Tooth Sensor supplied in the Kit of Parts actually did give direction information. It provided a single output pulse for each gear tooth passing by, with a short pulse width indicating one direction and a longer pulse width indicating the other.

Sounds pretty cool. Also sounds like it had more smarts than just an simple hall effect sensor. Was this the pre CRIO kit of parts?

An encoder (in FRC parlance) is a sensor that detects rotation. The sensor technology can be resistive (potentiometer), optical, or magnetic (Hall sensor) to name a few.

Most encoders in FRC deliver pulses, so many pulses per revolution (except potentiometers). Using two carefully-placed sensors can deliver both speed and direction information.

The choice of the sensor technology to use depends on the application: Optical sensors can operate far faster, Hall sensors are great in sensing things magnetic, meaning your sensor wheel can be an existing gear or sprocket. In most cases, size/weight/cost/performance are the general tradeoffs.

The word Encoder has many definitions; here we are referring specifically to a rotational encoder.