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old schematic required


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hi there you mad mad Midiboxers.


This is a rather silly request, but I need the schematic of the old  non-mios Midibox64 core module.


It used the old PIC16F877.


I cannot locate my copy and it is no longer published by uCApps.


Does anyone have a copy? Does anyone know of where it might be archived?


Thanks in advance for any help in this matter.

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Thanks for the interest digineural.


I must have been thinking of the Midibox64 V1, which was based on the PIC16F877, but I now recall V3 was far better to work with.


I have some PIC16F877's burned with Midibox64_v101b_mbhp.hex firmware, so I thought I would knock some MIDI stuff together.


regards to you

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Hi Janis and thanks for the input and effort, I appreciate it.


It seems that you have found the page I have been searching for. I used to have all the original info

when Midibox was quite new, but things easily go adrift in the sea of info.

It seems certain that the schematic for V3 is pin compatable with my old chips, so

I had better get my old burner out and try remembering it all again.


Thanks again, and to anyone else who looked in.


This topic is satisfied.

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Thanks to TK.


Yes, I built the thing last night (20 Mhz crystal) and I even threw an LCD display in, then I unzipped the firmware (midibox64_v101b_mbhp.hex) and tried to burn it into a virgin PIC16F877, but alas, the software I am using (Piklab on Linux) - although perfectly good when it comes to its assember- refuses to write hex files. So I wondered if anyone knows of a simple (Linux) method of stuffing the chip with hex?


The last time I did all this I used MPlab under Windows, and to be honest, I had no problems - the obvious solution I suppose is to revert to Windows etc.

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Just had another look: I never set the config bits! Forgot that they are not part of the hex file (or so it seems).


Anyway, programmed pic ok, stuck it in circuit but display (although lit up) was blank. Hmm.

Tacked two wires to a piezo sounder, and placed across MIDI out pin of chip: lots of activity heard: seems ok.


My newly soldered contrast pot (both contrast pot and brightness are both soldered to the actual display - not the core module) needed setting. The only decent 10K pot was a little square multiturn - wasteful but it works. Now I have lift off.


Next thing: if I connect my MIDI keyboard to core module, do I need to tell the program to merge it with the main stream?. . or is it done auto?

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I guess that the MIDI merger is disabled by default to avoid unwanted loopbacks.


The MIDI OUT should send a lot of "random" CC values when J5 pins are open (neither connected to pots, nor to ground)


If this doesn't happen, then the PIC very likely doesn't run.

Yes, this could be a problem with the config bits.


Here is the expected configuration (which was manually selected):



Best Regards, Thorsten.

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Thanks again TK.


I had clamped all 8 analog inputs to the wiper of a 10K pot (the other ends to +5V and 0V of course) so no pick-up problems there. The trouble was indeed in the configuration. In fact, although the config is held in the HEX file, my programmer still requires it to be manually entered, without this, the programmer sets the config as external RC oscillator, therefore no go Joe. (Thanks also for that link).


I suspected that the MIDI merge has to be switched on, but is it achieved via the panel buttons, or by sysex? I do hope it's a simple matter

of menu selecting, and not sysex.


Anyway, I have the whole thing up and running, and having found some old chips so am now knocking up a board to read 32 pots and 16 buttons.


As a matter of interest > this seems not to affect the controller's functions, as it sends MIDI CC messages fine < but I noticed that when the thing is first switched on, the display says 'MIDI TIMEOUT' . I wonder is this something to do with Sysex?



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Both options are available: the MIDI merger can be enabled via the menu interface (you need a LCD for this) or optionally via SysEx

See also this tutorial: http://www.ucapps.de/midibox64_tutorial.html


MIDI Timeout: could happen if there is a problem with the optocoupler circuit - it could be, that your MIDI IN isn't working yet?


Best Regards, Thorsten.

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Thanks TK, your interest is truly appreciated.


That link is excellent, as it answers all my questions re MIDI.


You said " MIDI Timeout: could happen if there is a problem with the optocoupler circuit - it could be, that your MIDI IN isn't working yet?"


I think you are correct. I have not yet fitted an Optocoupler circuit, and I imagine the Midibox is looking for a reply to some code. I will get that sorted out very soon. But I need a few buttons for Menu and perhaps a few triggers, so I am just in the middle of stuffing some strip board with a couple of chips. Soon as that's done and tested I shall connect the MIDI I/O correctly, and see what happens. The Midibox output drives the MIDI in of my old Soundblaster card, and all tests are good in that direction.


Best regards

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