Datasheet

Product data sheet Rev. 2 — 21 October 2013 76 of 150

NXP Semiconductors

LPC4370

32-bit ARM Cortex-M4/M0 microcontroller

7.20 Counter/timers and motor control

7.20.1 General purpose 32-bit timers/external event counters

The LPC4370 include four 32-bit timer/counters. The timer/counter is designed to count

cycles of the system derived clock or an externally-supplied clock. It can optionally

generate interrupts, generate timed DMA requests, or perform other actions at specified

timer values, based on four match registers. Each timer/counter also includes two capture

inputs to trap the timer value when an input signal transitions, optionally generating an

interrupt.

7.20.1.1 Features

• A 32-bit timer/counter with a programmable 32-bit prescaler.

• Counter or timer operation.

• Two 32-bit capture channels per timer, that can take a snapshot of the timer value

when an input signal transitions. A capture event may also generate an interrupt.

• Four 32-bit match registers that allow:

– Continuous operation with optional interrupt generation on match.

– Stop timer on match with optional interrupt generation.

– Reset timer on match with optional interrupt generation.

• Up to four external outputs corresponding to match registers, with the following

capabilities:

– Set LOW on match.

– Set HIGH on match.

– Toggle on match.

– Do nothing on match.

• Up to two match registers can be used to generate timed DMA requests.

7.20.2 Motor control PWM

The motor control PWM is a specialized PWM supporting 3-phase motors and other

combinations. Feedback inputs are provided to automatically sense rotor position and use

that information to ramp speed up or down. An abort input is also provided that causes the

PWM to immediately release all motor drive outputs. At the same time, the motor control

PWM is highly configurable for other generalized timing, counting, capture, and compare

applications.

7.20.3 Quadrature Encoder Interface (QEI)

A quadrature encoder, also known as a 2-channel incremental encoder, converts angular

displacement into two pulse signals. By monitoring both the number of pulses and the

relative phase of the two signals, the user can track the position, direction of rotation, and

velocity. In addition, a third channel, or index signal, can be used to reset the position

counter. The quadrature encoder interface decodes the digital pulses from a quadrature

encoder wheel to integrate position over time and determine direction of rotation. In

addition, the QEI can capture the velocity of the encoder wheel.