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latigid on

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Posts posted by latigid on

  1. Here is the reference:

    http://ucapps.de/midibox_ng_manual_ngl.html

    Quote
    • %d: will output the value (minus specified offset) in decimal format
    • %u: same like %d, but value always in unsigned format
    • %x: will output the value (minus specified offset) in hexadecimal format
    • %X: same like %x, but with capital letters
    • %c: will output the value as character
    • %s: will output an empty string. In conjunction with padding values it could save some memory, e.g. "%20s" will output 20 spaces
    • %i: the ID of the EVENT
    • %p: for EVENT_BUTTON_MATRIX only: the pin number of the matrix
    • %e: the MIDI event of the EVENT (up to 3 hexadecimal values, always 6 characters)
    • %m: the minimum value of the EVENT which has been specified with range
    • %M: the maximum value of the EVENT which has been specified with range
    • %b: a binary digit: * if value >= (range/2), o if value < (range/2)
    • %B: a vertical bar which works like a meter.
      In conjunction with various fonts (selected with &<font>) alternative icons will be output instead.
    • %q: current selected bank (q is a rotated b - do you see it? ;-)
    • %C: clear all LCDs
    • %%: outputs the % character

    It's possible to format the output by adding following specifiers after the percent (%) character. In following example the %d (decimal value) is used, but this works with any format type:

    • %3d: the value will be padded with spaces to 3 characters, and it will be output right-aligned, e.g. " 1", " 10", "100"
    • %-3d: the value will be padded with spaces to 3 characters, and it will be output left-aligned, e.g. "1 ", "10 ", "100"
    • %03d: the value will be padded with zeroes to 3 characters, and it will be output right-aligned, e.g. "001", "010", "100"

     

  2. Is there a specific problem you are trying to solve? 

    My gut feeling is that we should minimise the length of high-speed digital signals (lower impedance/inductance causing signal-integrity loss; less EMI) and buffer them to take load off the MCU, also minimising the number of interconnections. Things that interface to the shift registers (LEDs, switches) are much slower and could run over longer traces or cables.

    In practice I'm not sure if it really matters. Try for logical layouts and see how the performance is.

  3. Thanks for the follow up! You're certainly not to blame for this, so I'll ask the fab what happened. Looks like the copper substrate was scratched from the beginning or some of the mask rubbed off before etching.

    Let us know privately with any subsequent order and we can spare you some $$ for the trouble.

    • Like 1
  4. Hi Adam,

    I don't fully get it: are you able to illuminate both superflux LEDs (red) in this column? Also, is it the _L or _R board and what is the version number?

    You can see the board trace should connect all "red" LEDs in this row, but the SJ part will not be connected to the LED until the resistor is placed. This sets the output for the MEC LED but you were talking about superflux?

    2019-11-05.thumb.GIF.f51f2d893806912b51c

     

    I can see a scratch on the board in your picture, is it related? If you're feeling masochistic you could sand back the solder mask and see where the copper stops (if it does).

    If the trace I marked with a "?" really doesn't connect, I would suggest to use a 1k THT resistor as indicated with the red mark. It would also be possible to use one of the 2/3 positions, but the matrix addressing will need changing in the HWCFG file.

     

  5. Just now, TK. said:

    This isn't correct, see also the SN74HC595DR datasheet: http://www.ti.com/lit/ds/symlink/sn74hc595.pdf

    Output drive current is 6 mA, which means in other words: you've to add an internal resistance of ca. 800 Ohm to the calculation.

    This could be doublechecked by clamping an output to ground, and measuring the current draw while the pin is set to logic-1.

    Best Regards, Thorsten.

    True as far as I understand the structure of the chips, though I think the maximum current drawn could be 150mA per chip IIRC? Normally if they are overloaded the supply voltage begins to sag.

    In this case it's academic though, as we use bipolar driver transistors for both sides of the matrix. So the actual current could be somewhere near the ohmic value.

  6. Four hours of stress testing just done. In MIOS Studio "set dout x 1" where 0<x<7 inclusive sets the sink sides active and  "set dout y 0" where 8<y<15 inclusive sets the source sides active. I tested a mixture of red, green and mixed LED colours.

    No burn out or overheating of any parts. Colour and brightness after the test are identical to those of a non-stressed board (running in normal multiplexed mode for both).

    This doesn't mean that you should run your matrix like this (and if you did you would lose control over LED and switch registration), but it shows that a "failure" with the LED drawing the full theoretical current will not instantly damage the LED. At least there will be enough time for you to notice and reset the unit :-).

     

  7. No worries!

    I know Peter and a few others ran a mixed colour scheme and it seemed to work out well, though the current drive through the LEDs might get a bit non-linear I think.

    Stress test is currently running with the "worst-case" matrix fully on, so no multiplexing. Half an hour in and nothings burned out yet. What do you think is a fair test time?

  8. If you're concerned with the LED lifetime then simply increase the values of the RJ resistors to a current you are comfortable with. I would consider the probability of an LED matrix "freezing" in the way you describe as a low risk though.

     

  9. Not sure if this is a grumbling post about schematics not being supplied? You bought the PCBs, so you are welcome to the schematics if you send an email in reply to your order confirmation. Snippets of the schematics are supplied in part throughout the troubleshooting thread. This is generally a better way to provide targeted help to builders and I'm very responsive in that regard.

    So, rant over! :-) If that wasn't your intention, then I'm sorry.

    The LEDs are indeed multiplexed as is typical for MIDIbox projects and driven through bipolar transistors. The key datum is actually the peak forward current per chip, listed as 100mA. True, our multiplexing speed and fraction is slower and larger than the given conditions. All of the LEDs have been put through a burn-in test using the same circuit as the one in the SEQ, so we know that they are good. Also, these are superflux LEDs with much higher current-carrying capacity than your typical LEDs.

    Have fun building!

  10. Hi,

    We currently use this one from Reichelt:

    https://www.reichelt.de/d-sub-kabel-1-1-25-pol-stecker-stecker-1-8-m-2-0-m-ak-4010-p3997.html?&trstct=pos_0

    TK. suggests up to five metres would work.

    So I guess that means 16 feet in Freedom Units. Unfortunately I couldn't find a decent one from Mouser but if you need to get all of your parts there,  571-1658613-2 plus 26-way ribbon could do the job (and would be less bulky than a cable). Another famous sequencer does it that way :).

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