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voronin75

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Posts posted by voronin75

  1. So the problem is generally solved by RC filter (with 100 ohm+100pF in serial to gnd)  at the end of the SC line. (does not work with the second filter on the RC line)
    But there are two questions - the SHIFT button does not display BPM (led is ok), and the exta buttons column  work only as a track selection, but mute / unmute does not work (although leds displayed if mute / unmute on SEQ)

    I will search, but maybe there are any ideas?

     

  2. 1 hour ago, latigid on said:

    The observations suggest interference on this clock line such as antenna effects (EMI) from sub-optimal trace routing/cabling, or transmission line reflections. Hence a suggestion of an RC (resistor + capacitor) shunt termination (forum search will turn up more info). 

    Grounding to the "chassis" seems an odd choice and means there is relatively high resistance between the chassis and system 0V. Otherwise the clock that is wired in parallel to all circuits would be shorted out, no?

    Grounding on the chassis I meant the direct connection of the last SC output to the ground of the power supply. Without RC shunt termination. Everything works well  with one exception. when you turn it on, you must reconnect the SC-> GND bus) Otherwise  the device does not start correctly. I am an amateur))) I will try.

     

  3. The problem is solved by connecting the last output in the SC chain to the ground (to the main chassis ground, not the last board gnd) It works correctly and stably. I still do not understand why. Can someone explain? Or i missed something?

    I found the answers here. I think this is what latig on said.

    On 17.08.2010 at 0:58 AM, TK. said:

    After I read the blog and want to thank you for starting this report! It makes the signal integrity issue better understandable and will help us to give newbies some arguments, why SRIO chains are usually limited to 16 shift registers (longer chains could require expert knowledge and technical equipment to get stable transfers)

     

    There are two points I would like to add:

     

    • we get a more difficult situation once a DIN chain is clocked by the SCLK signal in parallel to the DOUT chain: parallel chains can result into two "ringings" (one from the DOUT, one from the DIN chain - if they have different lengths resp. impedances.
      The situation will become even more difficult if DIN/DOUT registers are connected to SCLK in mixed order, in this case it can happen that the serial data won't be shifted correctly anymore due to setup/hold time violations caused by unbalanced clocks (with different delays) at SR inputs.
      This results into the effect that bits could be missed or added in the DIN and/or DOUT chain at random moments and positions (-> flickering LEDs, random button events) - this effect could vanish if you put your finger on the SCLK line (see also next point)
    • by probing a signal with your scope you will add a capacitance to ground of ca. 10..100 pF (so far I remember, the value could be wrong or different for your scope). This has to be considered while comparing waveforms with theoretical calculations.
      This means in other words: currently your waveform looks nice, but once you remove the probe the "untouched signal" could be bad again. You won't see it (as you removed the probe ;))
      Seppoman recommented AC termination to solve this - it works! E.g., at the end of the chain add a 100R +100 pF to ground (so far I remember, meanwhile he even prefers higher capacitances)

     

     

    Best Regards, Thorsten.

     

     

     

     

  4. 22 hours ago, latigid on said:

    Inrush current issue? Though the LEDs seem to be driven with 1k, so not terribly high. Grounding issue between power supplies? Check all 0V are common. SRIO integrity? Try buffering the J8/9 signal and/or terminating the chain with an RC shunt.

     

    latig on thanks for your answer! The grounding of the blm power supply is connected directly to the seq ground.

    Can you explain  buffering the J8/9 signal and/or terminating the chain with an RC shunt.? 74HC125 chip  on minicore is buffer, right?

    Works fine only two scalar in different combination CS setions. How check SRIO integrity?

    Here short video of trouble

     
  5. Hi all midiboxer) Need your help!

    I built blm 16x16+X  on PCBs.
    CS consists of two printed circuit boards: the first contains 16+Xx8, 2 scalar modules are installed under it, the second 16+Xx8+X contains 3 SCALAR modules
    The device connects to midibox seq v4 normally on port IN3
    Firmware PIC4620 blm_scalar_v1_1,
    Power from 5V 3A power supply
    Test of the first section 16x4 with SCALAR module -ok
    The next section test is 16x8 with two SCALAR modules -ok
    Test of the next section 16x12 with three SCALAR modules - all the LEDs blink, the buttons transmit the midi event to the midi monitor if you click
    Section test 16x16 + extra - the device goes crazy, all the LEDs are lit randomly, the buttons transmit the midi event to the midi monitor

    All the same if you change the scalar modules in any configurations, the same if you connect the modules arbitrarily on the board i.e. e.g. starting at line 5, etc.)
    Those. Errors on the PCB seem to be eliminated, on the scalar, it seems, too. Remains Core (voltage drop in the last scenario to 4.9V)

    Connection length between SCALAR modules about 100mm

    jumpers on Core J5 are not installed as stated in the description of the firmware  project_without_ain.hex  (the same result with jamper)

    Has anyone come across? Please tell me where to look?

    Regards

     

     

    ??????????_viber_2020-02-24_23-18-55.jpg

     

     

     

    ??????????_viber_2020-02-24_23-18-50.jpgModules are installed under CS and connected by a ribbon cable about 10 cm

    ??????????_viber_2020-02-24_23-58-29.jpg

    ??????????_viber_2020-02-24_23-19-05.jpg

  6. I have seq v4 with wilba CS working fine.
    I add the line driver + aout ng modules connected by scheme for seq users from www.ucapps.de/mbhp_line_driver.html (j8/9 of core to j1 cs; j2 to j2 transmiter; j19 of core to j19 transmiter etc.)
    and in result have crazy seq.(screenshot) and MC3486, MC3487 seems warm.
    Check for shorts on line driver pcbs- all fine. Pinout seems normal. Some result without any connection fron transmiter. AOUT seems work fine.
    Tell me please where to look for error. Thank you.

    ScreenShot_20180514081621.jpeg

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