Dmx dc 8 ssr

[chilloutdocdoc]

Well, after a few days of playing around in Eagle. Here is the design I've wanted to do. an 8 Channel DMX DC controller.

I wanted something capable of controlling floodlights, that was small, controlled by DMX, and was cheap. So thus the DMX DC 8 SSR.

I would really appreciate feedback before I send the board off because this is my first design and a lot of you have a LOT more experience than I do. I know some of you are going to say that there's nothing on the silkscreen in terms of part definitions. Cheat sheet: 1206 = fuse; 0805 = capicators; 0603 = resistors. The BOM is about $7 in one off quantity, and drops from there.

I designed it to be run at 12V. The outputs should be capable for 1-2A per channel, but it will depend on how warm the board gets.

BOM Link: http://www.mouser.com:80/ProjectMana...sID=4c74d86cb5

Schematic Image: http://img9.imageshack.us/img9/9914/schematics.png

PCB Image: http://desmond.imageshack.us/Himg249...png&res=medium

[LabRat]

Are top & bottom both GND planes? If yes, then I would think some additional conduits in the area of the voltage regulator would help with the thermal dissipation.

One other question... how are you going to mount these? (I keep forgetting to add mounting holes to my boards).

When can I get some :o)

[chilloutdocdoc]

Not quite. Top is a GND plane. Bottom is a +12V plane for the outputs, it's probably not necessary, but I figured it couldn't hurt.
Somebody else had asked about the input/output wiring in chat.
The inputs are Power, Gnd, DMX +, DMX +, DMX -, DMX -, plus a program header.
The outputs are wired Vin (Fused) 1, 2, 3, 4, Vin (Fused), Vin (Fused) 5, 6, 7, 8, Vin (Fused)

I'm going to place a seeed order in the coming week. I'll trade you some of my design for yours if you have any. PM me. I haven't tested it yet, this is a prototype run, so I won't be ordering extras. (yet)

[David_AVD]

Not bad Josh.

I notice you went for a non-standard ICSP header pinout.

Does that PIC have an internal pull-up on MCLR ?

Have you tried ICSP programming with the FETs in circuit?

[budude]

A couple things - you have pin 4 (MCLR/VPP) floating - you should tie that up to +5 with a 10k resistor to be sure you don't get any spurious interrupts (it's normally the ZC input). Also - no oscillator? I didn't think the internal clock of the 688 was fast/consistent enough for DMX? You have pin 2 driving an LED - what do you expect from that - is this going to be a heartbeat signal or something?

On your DMXIO - I'm assuming you are going to have a THRU configuration - if so I would suggest you alternate the Rx/Tx instead of 2xRx next to 2xTx - that way you can run a twisted pair nice and close up to the two pins.

[chilloutdocdoc]

Non-Standard.. What? Oh crap, gotta go look at, I had just referenced something (that was off Microchip Website I recall).
No I haven't tried programming it with the FETS in the circuit yet. That was one of my concerns, the worst bet would be that I could just solder and flash the PIC first.

[mschell]

I would vote against a non-standard ICSP layout or putting a header that doesn't do anything in the finished project.

Given the recent issues of PIC's getting erased when sent thru the mail, I think a working ICSP header is almost mandatory these days on a board. I'd really rather not have to take out the PIC to reflash it.

[budude]

I would vote against a non-standard ICSP layout or putting a header that doesn't do anything in the finished project.

Given the recent issues of PIC's getting erased when sent thru the mail, I think a working ICSP header is almost mandatory these days on a board. I'd really rather not have to take out the PIC to reflash it.

Well - definitely mandatory for an SMT version for the DIY community!

[David_AVD]

The standard one compatible with the PicKit (and clones) is a 6 pin header. Some people use a 5 pin header, but I use the whole six to avoid alignment confusion.

1 Vpp
2 Vcc
3 Vdd
4 PGD
5 PGC
6 no connection

[mschell]

Well - definitely mandatory for an SMT version for the DIY community!

Agreed! I didn't even look at his PCB layout till after I made the comment. Once I saw the SMT, it's required for sure!