MIDI Box Design Questions

[Crypto71]

Hi,

I have got a few things I could not yet figure out, so please help  :)

1.) Can I connect true switches (German: Schalter) to digital inputs or only push buttons (German: Taster)?

2.) I want to connect more than 64 switches (or push buttons ;) ) to the digital inputs. I have found that there is a test program for the MIDI box (MIOS) to connect up to 128 switches/buttons, 32 (I think) analog inputs. What changes to these files would be necessary to do the same otherwise as can be done with the standard MIDI box MIOS?

3.) Design of the circuit boards: each of them contains a power supply for a small group of buttons/faders etc. Normally, it looks like that, there is a power supply going to, e.g. 8 buttons. Can I connect more than the amount of faders/buttons etc. to the same power supply on one circuit board? E.g.: connect 17 analog sliders to the power supply of one AIN-board? Or do I have to split my sliders into groups and connect only that amount of sliders to power that is located on one AIN board?

4.) The analog sliders are supposed to have 10kOhm. However, when connecting several sliders to the AIN boards, we connect them parallely, so that the overall resistance of a group of sliders/pots etc. is not 10kOhm but much lower than that. Does the MIDI box circuitry take this into account somehow?

Thanks a lot for any help in advance,

Crypto.

[doc]

Hi,

1.) Can I connect true switches (German: Schalter) to digital inputs or only push buttons (German: Taster)?

Yes, I think so

2.) I want to connect more than 64 switches (or push buttons Wink ) to the digital inputs. I have found that there is a test program for the MIDI box (MIOS) to connect up to 128 switches/buttons, 32 (I think) analog inputs. What changes to these files would be necessary to do the same otherwise as can be done with the standard MIDI box MIOS?

It depends a little bit on the application you want to use. Tell us about it.

If you reach a limit, you can always use more than one CORE to benefit from more controls.

3.) Design of the circuit boards: each of them contains a power supply for a small group of buttons/faders etc. Normally, it looks like that, there is a power supply going to, e.g. 8 buttons. Can I connect more than the amount of faders/buttons etc. to the same power supply on one circuit board? E.g.: connect 17 analog sliders to the power supply of one AIN-board? Or do I have to split my sliders into groups and connect only that amount of sliders to power that is located on one AIN board?

Normally it doesn't matter where you get ground or +5V from. It's always the same power supply.

In case of AIN it is useful to use a kind of star-grounding to group the ground-lines to the pots/sliders.

You can try to connect your controls with ground/+5V as you like. But if you get random values from the pots/sliders you should group your groundlines in a "star" manner. (AIN = analog!)

The +5V you can connect from/to where you like.

4.) The analog sliders are supposed to have 10kOhm. However, when connecting several sliders to the AIN boards, we connect them parallely, so that the overall resistance of a group of sliders/pots etc. is not 10kOhm but much lower than that. Does the MIDI box circuitry take this into account somehow?

Wrong!

Each middle pin (each slieder) goes to a dedicated Input of an AIN chip.

Remember: You don't control resistance with the pots - you control voltage!

The AIN gets an input voltage from the pot/slider between 0V and +5V and the PIC interprets this as a value between 0 ... 127.

Hope this helps

Greets

DOC

[Crypto71]

Hi,

OK, here is my conversion project:

I have an old electric organ that already has MIDI output installed for the black and white keys of the keyboards and pedal.

Now I want to MIDI the drawbars and buttons and also install foot switch connectors.

There are 122 digital inputs (switches, no push buttons) to MIDIfy and 42 analog inputs. As far as I can see, this can be done with a single core module and MIOS, if I use a different system program for it. I have already built the AIN modules and the DIN modules, and the core module is also ready to go. I have also built an LCD panel

into the organ that seems to work (was first thing I checked after all the circuit boards were done).

So please tell me now that my plans can actually work ;)

Crypto.

[ranger930]

Hi,

switches are working !

mfg

ranger930

[nILS]

Crypto - sounds reasonable and should work ;-)