DMX Chip

[cleventhal]

Can someone recommend a DMX chip, PIC Controller, or RS-485 chip to make a simple single channel DMX encoder box. Basically I want to be able to have a box with a relay input and then be able to set the DMX circuit to a preselected DMX channel and level; the single channel box would then be used to active a DMX controller.

Thanks,

Craig

[Matt_Edwards]

Craig,
Welcome to Do it Yourself Christmas.

If you are OK with AVRs, I have working DMX TX code for a tiny2313 I can give you.
I have TX'd using both USART and simple Bit Banging.

Henne's website also has good Resources for DMX
http://www.hoelscher-hi.de/hendrik/english/ressources.htm

Others here may have already done this so they may have a better solution.

What is your level of electronics and ucontroller programming ability?

hope this is helpful
Cheers
Matt

[DynamoBen]

This might work also, its something I made last year.

http://doityourselfchristmas.com/forums/showthread.php?t=4723

[NogginBoink]

Matt, what were your experiences with bitbanging DMX? What CPU speed were you using?

[DynamoBen]

I'm also done DMX with a 16F268 and PICBasic and a Parallax Propeller.

[Matt_Edwards]

Matt, what were your experiences with bitbanging DMX? What CPU speed were you using?
Bit banging I used a ATiny2313 at 12MHz.

I have uploaded my TX Code in the File Library Here (http://www.doityourselfchristmas.com/forums/dynamics/showentry.php?e=15&catid=22) it is NOT the Bitbang version. I need to find that at home.
Cheers
Matt

[Blackbeard]

Need to make sure I'm understanding all of this, so can someone provide definitions.

What is bit banging? Is that a reference to Assembler?

What are you describing when you refer to a transmitter? Receiver is obvious to me, but is a transmitter what receives the DMX and does something with it (other than rebroadcast it)?

Thanks for tolerating my ignorance.

steve

[Matt_Edwards]

Bit Banging means you transmit a structured serial comms by turning a pin on and off manually. If you are familiar with RS232 serial comms, you will then understand start and stop bits, and data bits.
Basically, your code has to ensure the timing is correct and all the overhead & data bits are all in the correct order.

The module produces DMX code and i found it quite handy when developing my DMX RX modules as you can make it create an known reference signal. You can also use other outputs for Scope triggering on Break or a specific channel.

Cheers
Matthew

[Blackbeard]

Matt,

Thanks - I reread your first post and it's obvious now. I somehow overlooked the USART part. Makes sense now.

steve