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latigid on

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Posts posted by latigid on

  5. CV/Gate Breakout/Buffer Board 2.0

    in Design Concepts

    Posted

    Okay, I think I'm done now.

     

    I think that it looks okay but I'm not 100% sure on the regulator circuit. If somebody could check that would be great.

     

    Also: no answer as of yet on the MIDI IN/OUT 3 situation. In any case, I have brought out the 3.3 V and 5.0 V connections. 

     

     

     

    gallery_5453_5_81634.png

     

    gallery_5453_5_95973.png

     

  6. 11 Midi Out Ports on MidiBox Seqv4

    in MIDIbox SEQ

    Posted · Edited by latigid on

    It might involve specially programmed 16F88s. Note that the Quad IIC has a circuit-level implementation (EDIT pins 12 and 13 as shown on the schem.) for addressing the IICs (MIDI OUTs), so you might need a custom PCB for more outputs.

    • Like 1

  9. CV/Gate Breakout/Buffer Board 2.0

    in Design Concepts

    Posted

    If you can't beat 'em, join 'em.

     

    Following a discovery that the I am working on a revised design based on SN7407 level shifters.

     

    (If you want a board from the the buffers work as expected, please PM me for details.)

     

     

     

     

    Simple enough circuit but I have several questions.

     

    First off: any problem with cascading the buffers this way? The idea is to have a switchable output between +5 (also serving as Vdd for the ICs) and an adjustable voltage which is derived from a low-dropout regulator (say 12 V or higher). 

     

    It is more simple to route when the output of the first buffer connects to the input of the second, but would it be better to tie the inputs of both buffers together instead?

     

     

     

    What should the handling of MIDI IN 3 and MIDI OUT 3 be?

     

    Presumably MIDI IN 3 should go through an optocoupler with a 3.3 V pull-up on the Core side:

    http://ucapps.de/mbhp/mbhp_core_lpc17_midi3_midi4_extension.pdf

     

    Hence, no level shifting is necessary I think.

     

     

     

     

    But for MIDI OUT 3? 

    From the Quad-IIC schematic it is not clear whether the signal needs to be level-shifted. Will a 3.3 V output be compatible with the 8-bit core of the BLM?

     

    In this case, MIDI OUT 3 is level shifted:

    http://ucapps.de/mbhp/mbhp_core_lpc17_output_buffers.pdf

     

    For these two, it isn't:

    http://ucapps.de/mbhp/mbhp_core_stm32_midi3_extension.pdf

    http://ucapps.de/midibox_blm/blm_connector_mbseq.pdf

     

    There is a 3.3 V pull-up for the LPC core:

    http://ucapps.de/mbhp/mbhp_core_lpc17_midi3_midi4_extension.pdf

     

     

    Even though I will not use the LPC core, I plan to make it compatible with both for the greatest flexibility.

    Some clarification would be welcome.

     

     

    Cheers,

     

     

     

     

     

     
     

  10. Multiple MIDI OUT instead LTC Modules

    in MIDIbox SEQ

    Posted

    I'm not really familiar with the LTC module sorry, and I mis-spoke when I said MIDI thru before, of course you would be just duplicating the ports.

     

    It seems as if the serial functionality of the LTC module is not really useful any more. As far as I know you can use the buffer/level shifter IC to do this duplication.

     

    Hope that helps,

  16. CV/Gate Breakout/Buffer Board

    in Design Concepts

    Posted

    I think that we're over the 8 boards that I have available, but there's always the possibility that people back out etc. I am currently waiting on a bit of advice with regard to level-shifting the gates from the STM32 core, I'd rather not fry my pins :)
     
    I'm happy to organise another run if there is demand for one.

  17. Open drain mode for STM32 gates

    in MIDIbox SEQ

    Posted · Edited by latigid on

    My plan, unless anybody tells me otherwise (please do if this sounds stupid) is to solder 220 ohm resistor arrays to the core32 pcb in order to achieve the +5 V signals.

     

    Will this work with all outputs, including the 8 gates, MIDI I/O 3 and DIN sync start/clock? Or do these pins also require setting to open drain mode?

     

    Thanks,

     

    EDIT: or is 1k or 10k more appropriate? There is a +5 V rail running very close to J5A/B/C

  19. Open drain mode for STM32 gates

    in MIDIbox SEQ

    Posted · Edited by latigid on

    Just because I have things soldered already :smile:

     

    I was hoping for switchable gain between +5 V and something arbitrary like +12 V, but like you say I can just fiddle with the feedback resistors to tailor the gain level.

     

    Many thanks and greetings,

    Andy 

     
    Edit: the gates should be enabled, but not in open drain mode, correct?
     
    J5_ENABLED 1

     

     

     

  20. Open drain mode for STM32 gates

    in MIDIbox SEQ

    Posted

    Yes, this makes sense. Apologies, I did see this note but wanted to avoid the 74HC541 because I am already buffering the gates with my break out board:

     

     

    I wonder what is the best way to proceed while still using the board that I have. Do you think the buffers here would offer sufficient protection to simply use pull up resistors like I thought? Or would it be better to make use of a trimmer pot to have more control over the gain?

     
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