# 7.1. Glossary

ADC
  analog-to-digital converter
API
  Application Programming Interface
BLDC
  brushless DC motor — generally used in six-step control. Also known as PMSM
FOC
  field-oriented control — a type of control scheme for permanent-magnet synchronous motors or induction motors, where the stator field is controlled relative to the rotor field. It generally results in smoother torque, slightly higher efficiency, and higher torque-speed curve, compared to six-step control, but requires a measurement or estimate of rotor position, and is more computationally intensive.
HAL
  Hardware Abstraction Layer
ISR
  interrupt service routine
MCAF
  Motor Control Application Framework
PIM
  Plug-In Module — a small circuit board containing a processor and several passive components (such as bypass capacitors), meant to plug in to one of Microchip’s development boards.
PLL
  phase-locked loop — see AN1292 for the Microchip Application Note covering the PLL-style sensorless estimator.
PMSM
  permanent-magnet synchronous motor — generally used with FOC. Also known as BLDC.
PWM
  pulse-width modulation
QEI
  Quadrature Encoder Interface — the name of the hardware encoder counter peripheral in some Microchip devices.
SMO
  sliding-mode observer — see AN1078 for the Microchip Application Note covering the SMO-style sensorless estimator.