Designs for DALI Lighting Control


DALI (Digitally Addressable Lighting Interface) is a new cost-effective and energy-saving choice to control lighting systems in building automation and smart homes. Whether there’s a need to enable flexible lighting control or save power, the standard offers complete choice of dimming and switching on/off functions. DALI devices include fluorescent HF ballasts, wall switches, low voltage transformers, motion detectors, and gateways. Corridors or conference rooms rely on movement-controlled lighting to automatically switch on/off lights based on occupancy. Exhibition rooms may need different ambiences and automatic on/off controls. Daylight and night-light controlled light regulation is ideal for flexible lighting and energy-saving in offices. For all these needs, the DALI standard allows use of standard components and simple wiring to lowers costs. Data is transferred over a two-wire bus with a fixed rate of 1200 bps.

A DALI system can be controlled through the controller (master), which can send messages to control up to 64 slaves (with address 0-63). Multiple DALI networks (each with 64 slaves) can be connected to address more slaves. One out of 256 allowed levels between off and 100% can be selected to control the brightness level of a ballast. To simultaneously address multiple devices, the controller can send Group and Scene broadcast messages (e.g., “Group 1 go to 100%” or “Recall Scene 1”) to the slaves with each slave programmed with a group number and scene information. Different DALI networks can communicate via Wireless or RF communication. Many designs provide a Graphical User Interface to send commands and control the slaves. The write-up below shows implementation of the DALI master and slave system with the help of a microcontroller to control the brightness and fading levels. The designs also include user-friendly GUI and communication interfaces to program/debug the software.

  •  Flexible LED Lighting Control with DALI: This design implements a DALI system for LED lighting control with a microcontroller MSP430F2131. The MSP430F2131 uses its two onboard timers (WDT+ and Timer_A3) to control the fade rate and the LED intensity. The lighting application is controlled with a PWM generated from the Timer_A3 module. A simple look-up table of 255 PWM values is stored in memory. 1 represents 0.1% illumination and 254 represents 100% illumination. The WDT+ timer is used to fade the LED intensity by defining how long the LED takes to change from the current power level to the target power level. This reference design includes software, hardware design files & complete documentation. More on this Reference Design
  • Low-cost DALI Unit Using MCU: This reference design describes a low-cost DALI demonstration board to control illumination, for example, setting a lamp’s brightness level, turning on/off or dimming a lamp. It has a DALI master unit and four DALI slave units connected through a 2-wire DALI network. A Motorola MC68HC908KX8/KX2 microcontroller is used in a master-slave configuration. The master unit controls all the slave units and each slave unit can control a lamp. The LCD on the master shows the address and command data to be sent to the slave (for example, a lamp’s brightness level). Two shaft encoders can be turned to change the address and the command, and a pushbutton is provided to send the data to the slave units. The software is re-programmable by using a built-in interface. More on this Reference Design
  • DALI Master with ATxmega MCU: This reference design implements a DALI Master to control DALI slaves used in lighting control applications such as building automation and smart home. The design uses an Atmel ATxmega32E5 microcontroller. The DALI system needs DALI Master, DALI Slaves, DALI bus, DALI bus power supply, USB cable, and PC. Both USB and RS232 communication interfaces are provided to connect to host system. The DALI Master software is installed on a PC and commands can be selected from the commands list through the GUI. Then, the user can control the addressed DALI Slave. The MCU can be programmed and debugged by connecting an external programming tool. For this reference design, the hardware design files (Schematic, BOM, and PCB Gerber) and software source code are provided. More on this Reference Design
  • DALI Slave with ATxmega MCU: Here is a reference design of DALI Slave to control LED light strings based on ATxmega32E5. The DALI master for this slave is discussed above. The hardware includes three parts: MCU, DALI physical layer interface and LED drive circuit. The MCU is used to communicate with DALI master and light source. The LED string is controlled by the DALI commands through the MCU. The MCU can be programmed and debugged via PDI header. For this reference design, the hardware design files (schematic, BOM and PCB Gerber) and software source code are available. More on this Reference Design
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