GM5 Specifics

Design Concepts
1

I’m using the GM5 to simply input some monophonic, MIDI data (no ‘MIDI out’) from a microprocessor. Is it really necessary to opto-isolate this stream into the chip? I’m using the MidiBox schematic as a reference.

Also, the jumpers shown on the midi-box schematic have me a little baffled for my purpose. ‘1,0,0’ (1 I/Os)? Or ‘1,1,0’ (‘I only’) for J1,2,3.

J6 I can’t see a reference for.

J8 not sure about.

Thanks for any help.-Keith

2

Okay, figured out J6.

Still unsure about J1,2,3 configuration for my purpose.

And not still not sure what the distinction is between midibox.org configuration and polytec.com configuration (jumper 8)

To opto-isolate or not.

I’m using the GM5 to simply input some monophonic, MIDI data (no ‘MIDI out’) from a microprocessor. Is it really necessary to opto-isolate this stream into the chip? I’m using the MidiBox schematic as a reference.

Also, the jumpers shown on the midi-box schematic have me a little baffled for my purpose. ‘1,0,0’ (1 I/Os)? Or ‘1,1,0’ (‘I only’) for J1,2,3.

J6 I can’t see a reference for.

J8 not sure about.

Thanks for any help.-Keith

3

  1. Opto: Yes, always.

  2. config: Mainly the name under which the device shows up on your PC

  3. Jumpers: You probably want 110 (one input), won’t hurt to have the option of adding an output.

4

Thanks niLS. So even though the micro that is spitting out the MIDI dat is on the same board as the GM5, I still need to opto-isolte, yes? I thought the ground loop type problem was just because of a MIDI cable.

My device will be using the legacy MIDI on a Mac. So once I plug it in, I suppose I can just fiddle with the J8 jumper and see which setting responds.

Before your response, I was going to go with ‘110’ and let the output ‘hang’. So you coming up with the same idea just confirms that. Thanks again, Keith

5

One more question: since I’m not using a lot of the I/O (just one input) and not using the eeprom, do I need to ground the I/Os not used or are there pull-ups enabled on them? Thanks,Keith

6

If you jumper them accordingly the pins will be disabled on the gm5. So you can just let them float (also, as a general rule, you do not want to ground output pins, only inputs).