DOUT question

MIDIbox HUIs
1

Just a quick question about the DOUT which I’m sure some friendly expert can answer very easily  :slight_smile:

Am I right in thinking that +5V is ‘common’ and the - polarity is ‘switched’.

IE. On J3,J4,J5 and J6 there is a common VS, then D0-D7 for each LED. I am assuming that VS is the common +5V which is connected to all the anodes, and D0-D7 are the negative voltage for each LED and should be connected to the cathode of each LED ??

Therefore its common +5V and negative switched ??

2nd question about DOUT - do I need a resistor inline for each LED - IE. D0->resister->cathode

or is this all handled on the DOUT board

Thanks in advance

JD

2

Am I right in thinking that +5V is ‘common’ and the - polarity is ‘switched’.

other way round.

see: http://www.ucapps.de/mbhp/mbhp_doutx4_32leds.pdf

2nd question about DOUT - do I need a resistor inline for each LED - IE. D0->resister->cathode

or is this all handled on the DOUT board

yes and no if you are using boards from SmashTV - there is a resistor matrix that u solder to the pcb.

3

Phew! that was lucky I asked !!

So, VD is +5V and VS is ground ?? In my mind I had it the other way round - not sure where I got that from ! (probably from not wanting to be positive for VD !!  ;D ;D ;D)

OK, so next question concerning connections:

VS pin is common ground for all the LEDs on a DOUT module; and there is a VS pin on the DIN module which I assume is also common ground.

If I have a board with all my buttons (for DIN) and all my LEDs (for DOUT), can all the buttons and all the cathodes share the same VS ? IE. have a common ground rail on my board with one leg of each switch connected to it and the cathode of each LED also connected to it, and connect it to VS on the DOUT and VS on the DIN ???

Will that work ??

Cheers

JD

4

I’ve used common Vs for Leds etc, I haven’t mixed and matched between boards - it could make sense to share a Vs from the DOUT for all the Leds, and then use a common Vs from the  DIN for the buttons. It might make for easier debugging if problems arise.

5

IE. have a common ground rail on my board with one leg of each switch connected to it and the cathode of each LED also connected to it, and connect it to VS on the DOUT and VS on the DIN Huh

VS is ground. Ground is ground is always ground …

Sure you can connect every Gnd line together. This makes sense and it saves you from a lot of cabling sometimes. The only exception from this is the AOUT module. Here it is normally better to wire everything like a “star”. This prevents from ground loops (AOUT is “analog”). In the digital world this issue doesn’t matter.

DIN and DOUT ground lines can always be put together.

greets

Doc