Blatboy

Brainstorming: Connecting external 4X16 BLM

11 posts in this topic

I'm trying to think of a somewhat robust/easy to use way to connect my SEQ V4 (Wilba) to an external 4X16 BLM.  

I was thinking I'd use the "unused" 5 Pin DIN from the Quad IIC as my physical way out of the SEQ.  That leaves the actual BLM port free in case I ever get my hands on a 16X16 PCB (hint hint). I'm a little confused looking at the traces on the DIN connection.  Are only 3 pins actually used?  Would I be able to connect the 4 pin IIC output via the 5 pin DIN?

I loved the idea of using an off the shelf MIDI cable to connect the two.  Unfortunately, my BLM case isn't big enough to allow for a typical MIDI jack.  I already received the parts, so re-designing isn't an option there.  (Or...I'd rather not do it.) 

So... being that USB is a 5 pin connection, in theory I could make a custom cable that goes from MIDI to USB-A.  There is room in that case to put a simple panel mount USB-A jack in the case.  Another option of course would to just have a cable come out of the BLM to connect to the SEQ.  I'll probably just do that... and see if I can put some sort of strain relief on the cable coming out of the BLM.

Whaddya think?

 

:)

 

 

Edited by Blatboy

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Apologies.  I didn't get out my multimeter before. None of those 5 pins on the board are shorted.  The 3 pin jumper connection only connects to 3 of the 5 pins? I guess I don't understand how the 3 pin jumper headers are used with a 5 pin din connector.  I was under the assumption you used those 3 pin connectors if you wanted to use panel mount DIN jacks.  There is some real basic stuff here I don't get.

I can always just put in bodge wires (as Dave Jones from EEVlog would say) on the back of the board to connect the the IIC to the 5 Pin DIN...  However, I'm sure there's a more elegant solution! :)

Edited by Blatboy
to make it clear as mud

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The three pins were intended to connect a MIDI port if the BLM wasn't used, hence using the standard MIDI pins and leaving the others floating. This was before the days of MIDIO/MIDI8. So it should work to connect, but yull deffo need some bodge wirez maaate!

Keep in mind that the SRIO signal can get dicey if the cables are long. This would be the idea of the Line Drivers.

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Did you consider using the DIN8? Or do you plan to build a 16x16+X BLM?

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For some reason I thought you only had an LED matrix. So you actually need:

  • +5V
  • 0V (ground)
  • SO (serial out)
  • SI (serial in)
  • SC (serial clock)
  • RC1 (latch for DOUT)
  • RC2 (latch for DIN)

You could probably get away with sharing RC1 and RC2, but still that's more pins than a DIN5 has. Or did you power it somehow differently?

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Fer cryin' out loud. :fear:

I really should think things through a little better before I start posting.

I was confusing the connection with the core (4 pin IIC) with the 10 pin connection to the 16X4 BLM.  Oy.  Sorry to waste your time.  Thanks for the explanation of the 3 pin jumpers tho!

I do want to save that DIN8 in case I ever can get a 16X16 board.  

I'll see if I can find a panel mount DIN8 jack and do it that way.  I'll just make a cable coming out of the 16X4.  I was thinking around 60cm long... too long?

Thanks!

 

 

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9 hours ago, Blatboy said:

I was thinking around 60cm long... too long?

That's definitely pushing the limits - I'd say go with the line driver module.

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I guess it's really meant to be an internal connection.  I was being greedy.  I can physically get away with about half that... around 27cm.   Still need the line driver?

 

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It's one of those things where you just try and see how it goes. There are other tricks too, such as RC termination or buffering. All need extra circuitry, so give it a go first.

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Now don't quote me on that, but I've had this running with cables of 50cm length... The thing is that it depends on a number of variables, so you will have to try it. 30cm sounds like it will work, though. But - no guarantees...

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Understood.  Thanks so much.  In some ways, using the line driver is easier... at least I wouldn't have to make a cable and test all those pins haha.  

I'll test it with a ribbon cable and take it from there.

Thanks both of you so much for the great info.  I appreciate it.

w

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