MCP1650 datasheet(14/20 Pages) MICROCHIP

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LED Lighting Solutions Design Guide

www.microchip.com/lighting

LED Lighting Solutions

DMX512

The DMX512 interface (ANSI E1.11) has gained great

popularity in theatrical/entertainment lighting applications

because of its simplicity and low cost. It is based on a 250

Kbaud asynchronous serial interface that uses the standard

RS-485 differential line transceivers. Transmitter and

receivers can be implemented on most PIC microcontrollers

in a few lines of code. PIC microcontrollers that offer a

EUSART peripheral allow for the simplest and most efficient

implementation of the protocol.

Application note AN1076 offers an example implementation

of both a transmitter and typical DMX512 receiver on a

PIC18F2420 model.

The figure below shows an application example where

a PIC24FJ16GA002 implements a DMX512 receiver to

control three PWM output channels (each capable of 16-bit

resolution).

Literature on the Web

■ AN1076 – Using a PIC Microcontroller for DMX512

Communication

Wired Communication Solutions for Lighting

Many lighting applications require some form of

communication for remote control but also for diagnostic

purposes. Some of the most common interfaces used in

lighting are:

■ 0-10V

■ DMX512

■ Digitally Addressable Lighting Interface (DALI)

0-10V Interface

All PIC microcontroller families offer models that integrate

an Analog-to-Digital converter peripheral with a minimum of

8-bit resolution that allows them to connect to the industry

standard 0-10V interface with minimum external component

count. Most Flash PIC microcontroller models offer a

10-bit resolution ADC, while 12-bit resolution is available

on selected models. Each I/O pin is protected by a pair of

(clipping) diodes so to prevent latch-up and damages that

could follow from the incorrect wiring of a 0-10V interface

(over-voltage).

There are different 0-10V specifications based on

the intended application. The 0-10V control interface

for controllable ballasts is defined in Annex E of the

IEC60929 specification. The 0-10V control interface for the

entertainment industry is defined by ANSI E1.3-2001.

Digitally Addressable Lighting Interface (DALI)

DALI is a bi-directional

digital protocol that

requires a two wire

connection system

similar to the 0-10V

interface, but offers

individual lamp or group

addressability in a bus

configuration. The low

speed Manchester

encoding system used

allows for an inexpensive firmware implementation on

most any PIC microcontroller. Many PIC devices offering an

analog comparator peripheral can implement an advanced

power saving techniques as demonstrated in application

note AN809. Application note AN811 illustrates the

implementation of a bridge between DALI and a standard

RS-232 serial interface.

DALI Ballast Software Library

A DALI ballast software library is available for PIC MCUs

that comply with the latest release of the IEC60929

specification. Contact your local sales office for availability.

Literature on the Web

■ AN809 – Digitally Addressable DALI Dimming Ballast

■ AN811 – The RS-232/DALI Bridge Interface

RS-485

Transceiver

PIC24FJ16GA002

DMX512

PWM1

PWM2

PWM3

PIC24FJ16GA002 Controlling 3 PWM Output Channels

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