Microchip Technology APGRD004 Data Sheet

        LED Lighting Solutions Design Guide 

www.microchip.com/lighting

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).

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AN1076 – Using a PIC Microcontroller for DMX512

 Communication

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

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Digitally Addressable Lighting Interface (DALI)

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.

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.

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.

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AN809 – Digitally Addressable DALI Dimming Ballast

■ 

AN811 – The RS-232/DALI Bridge Interface

RS-485

Transceiver

DMX512

 

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PWM1

PWM2

PWM3

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