Unlike a brushed motor, the controller for a BLDC motor requires angular position information. Angular positions are sometimes accomplished using Hall effect sensors. Hall effect sensors are commonly used to synchronize the controller drive waveforms with the motor, allowing maximum torque even with zero rotation. Other methods include phase currents and/or voltages monitored by the controller. The controller effectively provides most, if not all, of the intelligence. Cost is reduced if no Hall sensors are used in the motor, but the starting torque is compromised. As a result, this application is usually limited to tools that do not require a high starting torque.