Datasheet

Product data sheet Rev. 4.2 — 18 August 2014 78 of 155

NXP Semiconductors

LPC4350/30/20/10

32-bit ARM Cortex-M4/M0 microcontroller

7.19 Counter/timers and motor control

7.19.1 General purpose 32-bit timers/external event counters

The LPC4350/30/20/10 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.

7.19.1.1 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 can 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.

7.19.2 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 causes the PWM to release all

motor drive outputs immediately . At the same time, the motor control PWM is highly

configurable for other generalized timing, counting, capture, and compare applications.

7.19.3 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 code 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.

7.19.3.1 Features

• Tracks encoder position.