One of the smallest DMX512 interfaces connected to the computers printer port is the LPR2DMX. It features all 512 slots and any start-code as it will be apart from the coming DMX512-2000 specifications. The start-code is also not fixed, it can be changed from frame to frame. That allows one to transmit every 0.1 second a frame with none zero start-code and the rest of the time frames with start-code equal to zero.

The LPR2DMX interface is quite fast. Using the DMX4Linux driver I was able to measure a frame update rate of about 37 512-slots-frames/second without problems. The LPR2DMX is also able to produce a DMX512 Signal with a Mark-After-Break of 4µs, as is was mentioned in the DMX512-1990 specifications. This mode was mostly included for testing receivers being DMX512-1990 conform. The default operation mode produces a 8µs Mark-After-Break.

All that was included into a PIC16F84-10 or PIC16F84A-20 in a way, that in-circuit reprogramming and firmware updating is possible. The LPR2DMX is released as free software under the GNU General Public License as published be the Free Software Foundation. This interface is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Download all necessary stuff now.

News:

Pictures:

• the prototype (enlarge(16kb))
  
• PCB (enlarge (each 21kb))
  
  (the crystal has a wrong value)

Download:

• GPL license (18kb)
• schematic (.pdf, 14kb)
• pcb (.pdf, 162kb)
• source (.asm, ziped) (5kb)
• source (.hex, ziped) (1kb)
• all in one .zip archive (190kb)

Links:

• programming the LPR2DMX
• drivers and test source for the LPR2DMX
• DMX4Linux: linux drivers for all interfaces
• Das Lula-System für Theater-Lichtregie: a program running on many computer systems supporting the LPR2DMX interface