DMX to Grinch/595 convertor

After posting that I had recieved no interest in a DMX to Grinch/595 converter I was asked by a couple of people for the information so I decied to create a simple how to.

This is the Schematic :

As you can see its a basic serialy enabled pic chip with a 40MZ clock.

Parts List :

Ic3 - PIC18F1220-E/P Ic4 - ST485EBN X1 - ECS-2100AX-40.0MHZ R1 - 299-120-RC C4,C5 - SA105E104ZAA

J1.1,J2.1,J5.1 - RJ45 jacks your choice J4 - 3 pin sip jumper J3 - 2 pin sip jumper

You will need the firmware. If you decide to build it PM me (RJ) with you email and I will be happy to email the hex file to you for the 18F1220. I know I could have used other pics but I had these and so it's what I used. I also would have to modify the Assm Code for other chips so I used what I had.

This is a explanation of the operation:

J3 is a termination jumper for the DMX. If this is the last device on the DMX line put the jumper on to terminate the 120 ohm resistor across the dmx buss. Dmx does not like to be unterminated. If you have other dmx devices to hook up after this plug them into the DMX out port and do not jumper the terminator. Pin #2 from my board goes to Pin #2 of the dmx and Pin #3 goes to pin #3.

J4 should be jumpered to the positive +5 side for operation. When you get the system finished you need to program the starting channel into the board before it will work. This is done by powering the board off. Start vixen with the dmx plugin set for the all the channels. Set the intensity levels to use the 256 mode not the 100% mode. create a seqence of 3 seconds or so and set the first channel to the intensity value of the channel you want the board to use as the first channel for the whole 3 seconds so this is the only value output for this channel. If you want the board to start on a channel higher than 255 than simply add the additional to the second channel.

So to start at channel 300 the first channel is set to 255 and the second is set to 45. now make sure vixen is set to repeat the seqence and start it. Now with the power still off on the board set the J4 jumper to the negative side and power up the board for 2 seconds. Turn it off and put the jumper back to the positive side (operation mode). Your board is now programmed and should work. remember in my example (ch 300) I would use vixens channel 300 - 364 to control my board now. If it doesn't act like you think it should reprogram it to channel 1 and try it.

You may reprogram it as much as you like the life of the eeprom is over 1 million cycles so you should have a hard time breaking it. It will remember the information for about 40 years with the power off so you dont have to reprogram it unless you want to change the channel assigned.

A straight through cable should be used between the converter and the Grinch/595 board. This convertor will run 128 channels so you can daisy out of a grinch to another one and it will work.

The distance from the convertor to the Grinch/595 should be able to be up to 20 - 30 feet.

I hope I explained this well enough for those who would like to build one. If not let me know.