The well-designed DMX Portal is an affordable DMX lighting controller. You can use the novel system to remotely control up to 512 channels through an IP-based network or directly interface them to embedded systems with a serial connection. It was designed to be perfectly suited for designers who want to off-load DMX management and refreshes from the main system controller. It’s also useful for distributed lighting systems where low-cost Ethernet wiring is more practical than expensive RS-485 wiring. The prototype includes an external EEPROM for scene storage and a Microchip Technology PIC18F4620 microprocessor. A WIZnet WIZ810MJ evaluation board is connected to the SPI on the PIC development board.
“The DMX Portal is a self-contained lighting controller for embedded systems and large distributed systems. I started this project because I wanted to be able to control moving lights and other special effects that use the DMX protocol from a system that was low cost and could change the lighting state based on digital triggers or simple commands from other systems. The WIZnet parts were a good fit for my design for several reasons. I was already using the PIC’s hardware UART for my optional RS-232 interface, which required me to generate the DMX serial output completely in software. Since the DMX output requires precise timing to generate the correct bit rate, I needed to disable all interrupts while the DMX data is being refreshed. The W5100 offers a very large buffer which is sufficient to store incoming commands arriving while the processor is unable to process the incoming data. Another reason the parts were a good fit was that the chip handles all the tasks of receiving and transmitting a UDP packet.”— Matt Ernst