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Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Fri Aug 31, 2018 9:29 pm
by Phil Smith
This is a picture of the pi with proto hat whilst testing.
IMG_20180408_195728.jpg

Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Thu Nov 01, 2018 11:41 am
by richbass
exciting!

Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Thu Nov 01, 2018 5:04 pm
by Phil Smith
Oh is that how you're supposed to do it! I'm embarrassed by my effort now..

Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Thu Nov 01, 2018 6:30 pm
by richbass
Phil Smith wrote: Thu Nov 01, 2018 5:04 pm Oh is that how you're supposed to do it! I'm embarrassed by my effort now..
Its not been tested yet :)
Looking neat is one thing, but actually doing what its supposed to is something altogether different!

And if it wasn’t for the hard work of others I would never have known how to do it at all.

Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Sun Jun 05, 2022 11:25 pm
by liebetim
Hi all,

I'm attempting to build one of these myself, following the instructions others have described above. Unfortunately so far I've been unable to output to my lights. I've attached an image of my setup and the datasheet for the IC I'm using. The list below is everything I've tried/checked so far. Hopefully someone else sees the missing piece that I'm overlooking!
  • Triple checked all wiring
  • Disabled bluetooth output per Massimo's instructions
  • Checked pin voltages:
    • Pin 4: 4.83V
    • Pin 8: 0.01V
    • Pin 12: 4.82v
    • Pin 16: 4.80V
  • Used a second MC348N
  • Swapped the +/- outputs (blue and yellow wires)
  • Tried multiple cap values, and using no cap at all
  • Ensured universe 1 output is set to UART
At this point, I'm not sure what else to try. I'm hoping there is a simple mistake that I'm missing. Any help would be appreciated!

Thanks,
Tim

Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Tue Jun 07, 2022 8:37 am
by GGGss
Without a scope or a DMX tester, you cannot judge if the DMX timing is respected so your fixtures will accept the DMX payload...
I can't see problems with your circuitry, except for the fact that you have all 4 blocks working, which is unnecessary. You can only use 1 of the 4 blocks.
I don't understand why the capacitance is between V+ and gnd. It will short-circuit high frequency voltage ripples.

Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Tue Jun 07, 2022 1:39 pm
by liebetim
GGGss wrote: Tue Jun 07, 2022 8:37 am Without a scope or a DMX tester, you cannot judge if the DMX timing is respected so your fixtures will accept the DMX payload...
I can't see problems with your circuitry, except for the fact that you have all 4 blocks working, which is unnecessary. You can only use 1 of the 4 blocks.
I don't understand why the capacitance is between V+ and gnd. It will short-circuit high frequency voltage ripples.
I appreciate you taking a look. I had initially wired it up with only one block and without the capacitor, but when it didn't work I figured I'd copy Phil's layout to a T. I may try some more experimenting. I'll post my solution here if I get it to work, otherwise I'll probably just pick up a USB adapter.

-Tim

Re: Low cost high quality DMX multi-chain interface for RPi

Posted: Sun Jun 12, 2022 5:28 pm
by liebetim
Turns out it was just a bad SD card. I clued into the issue when I kept having to re-flash the image after rebooting. Bought a new SD card and everything worked like a charm. I did also have to disable Bluetooth to utilize the UART pin.

I attached some pictures of my build along with the vero layout I came up with. I've also uploaded the files for the case to Thingiverse in case anyone would like to use the design.

Thanks to all!

-Tim