DMX3

For the last two years, I have been using a LED Floodlight to increase the volume of color I can produce and wash the walls in a myrid of color . While I have liked the Floods, what I wanted was a floodlight with an integrated DMX controller, so I did not have to wire each flood back to a DC Controller seperately.

I mulled around with some ideas and decided to take a RGB Pixel by JEC, and modifity it to suit my purpose. The original JEX Pixels were designed as a single board Pixel, with 9 LED in red, green and blue.

The code was freely available and very easy to work with. The DMX address is coded into the HEX file, and then flashed into the PIC.



DMX3 Features


  • Designed to fit to the rear of the LED Flood board
  • RJ45 Jack layout for Top or Side Load for flexibility
  • On board 5V Logic Power LED, with power fed options over CAT5 or local
  • Separate Terminals for each wire making the connections easier
  • Supplied as a bare board (from wjohn) or as a kit from WLC (TBA) Store Link

Versions


There are currently two versions.

DMX3 V1. This was the original board design, and uses a Connector pinout originally specified by John Chapman.

DMX3 V2. This is a modification to align the DMX connector to the P-DMX standard.

Design


The board is a simple design, there are two sections to the design; the DMX controller, and the DCSSR.

The DMX controller consists of the Comms IC and the microprocessor, PIC 16F688. The SSR section of the board is simply just a FET per channel.

Euro style screw connectors are specified for the board, and they are grouped in pairs (+/-) to make connections easy. They are labeled P1, P2, and P3.

The power input for the Flood light section of the board is via P4.

The DMX3 DCSSR is designed to switch DC loads between 0 and 60 Volts. The MOSFETs are rated to 10 Amps each, however as fitted to the PCB, I would limit to individual channel load to 2 to 3 Amps max. A suitable heatsink may be required.

Power Options


The Logic side of the board is designed to operate from a regulated power supply provided by 78L05 regulator. Bypass capacitors (C2, C3) are fitted for the regulator. The DMX3 board can be powered using a number of options:

  1. Via the CAT5 Cable and P4. This is the 'normal' operation for the board. 12 VDC is injected into the CAT 5 with the DMX signal, and is routed to the 78L05 regulator. Power for the SSR section is connected to P4.
  2. Via P4. Both the Controller and SSR sections of the board can be powered via P4, negating the need to inject power via the CAT5. A jumper is required for this option. The jumper is located to the right of P4, and is labelled PWR on the overlay. The minimum voltage required for this option is 8 VDC. While I have not tested this option above 24 VDC, the maximum rated input for the regulator is 35 VDC. In practice, the power dissipation by the regulator would be of concern.
  3. Via CAT 5 only. This is similar to Option 2. The jumper is required to be fitted to the board at PWR. The limitation for this option is the current capacity of the CAT 5. The rated current capacity of a single pair of CAT 5 is 0.577 amps. The board uses three pairs and therefore the maximum current capacity of the cable would be 1.7 amps. Remember, while the cable may be able to handle this current, it will be spread across all of the DMX3 DCSSRs connected in this manner.

Schematic



The schematic for the board is available in PDF format:

Parts List


I have built a Parts List BOM in Mouser. Click here to load it.

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