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SOLVED NodeMCU with Apa102 LEDs -> flicker

Discussion in 'Hardware Support' started by Kollektiv02, 9 June 2016.

  1. Kollektiv02

    Kollektiv02 New Member

    Messages:
    29
    Hardware:
    RPi1/Zero, +nodeMCU/ESP8266
    Hello,

    I have problems with flicker Apa102 LEDs with connected on a NodeMCU. The LEDs flicker not allways, but by different colours and brightness.

    But first my hardware on the TV:

    -Raspberry Pi 2
    -LPD8806 LEDs

    On the TV I have no problems. :)

    Now to the NodeMCU and Apa102 LEDs:

    I read this great tutorial to config my NodeMCU and Hyperion on the TV.

    http://www.forum-raspberrypi.de/Thr...esp8266-nodemcu-addon-wifi-led-controller-udp

    For the NodeMCU I use the software from tpmodding. You can find this in post 129 on page 9.

    What I have already tried:

    -reduced the lenghts of clock and data cable (80 mm)
    -used a shielded cable for clock and data (LAN CAT 7)
    -tested different baudrates ( 250000, 50000000 and 1000000)

    But all this get no improvement.

    Have you any ideas?

    Kind regards,

    Kollektiv
     
  2. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Is if a serial connection or wifi between the pi and the ESP ?

    Do you have level shifters between the ESP and the apa102 LEDs ?
    The datasheet for the apa102c says it need 0.7*vcc for a high input. This is 3,6v and the ESP is a 3.3v io
     
  3. Kollektiv02

    Kollektiv02 New Member

    Messages:
    29
    Hardware:
    RPi1/Zero, +nodeMCU/ESP8266
  4. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    • Like Like x 1
  5. Kollektiv02

    Kollektiv02 New Member

    Messages:
    29
    Hardware:
    RPi1/Zero, +nodeMCU/ESP8266
    Last edited: 10 June 2016
  6. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
  7. Kollektiv02

    Kollektiv02 New Member

    Messages:
    29
    Hardware:
    RPi1/Zero, +nodeMCU/ESP8266
    Hello,

    thanks for your proposal. Sadly the Octo28 is very big. The 74HCT245 is much smaller and cost only a fraction.

    I found this tutorial.

    https://learn.adafruit.com/neopixels-on-raspberry-pi/wiring

    In the tutorial is used a one wire LED strip. It occurred to me 3 questions .

    1.
    At my Apa102 ( two wire) I must only "shift" the Data signal or both (+Clock)?

    2.
    Must I flash the 74HCT245 with a sofware or is the chip ready to use?

    3.
    When I must "shift" the Data and the Clock signal, I can use one 74HCT245 or?

    I have the info from here:

    https://www.adafruit.com/products/1787

    Many thanks in advance.

    Kollektiv
     
    Last edited: 11 June 2016
  8. TPmodding

    TPmodding Administrator Staff Member Administrator

    Messages:
    1,280
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +nodeMCU/ESP8266
    you can shift both, you need no additional software. and the 74hct245 is a quad shiffter, you could shift 4 signals :)
     
  9. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    You need to shift both clock and data.

    The chip has 8 channels of which you only need to use 2
    You will have 6 spare inputs on the. 245 - these should be connected to ground rather than left unconnected.

    No software needed on the chip
     
  10. Kollektiv02

    Kollektiv02 New Member

    Messages:
    29
    Hardware:
    RPi1/Zero, +nodeMCU/ESP8266
    Hello everyone,

    today I installed the Levelshifter. Now it's work fantastic. :)

    I did not detect a flicker far. Thank you all. :thumbsup:

    Here is a link where you can buy it:

    https://www.conrad.de/de/logik-ic-puffer-treiber-texas-instruments-sn74ahct125n-pdip-14-1016253.html

    Now a few pictures:

    IMG_20160615_164716.jpg IMG_20160615_171858.jpg

    The Levelshifter is well protected.

    IMG_20160615_172010.jpg

    So I connected everything.

    IMG_20160615_172339.jpg

    @penfold42

    You written: You will have 6 spare inputs on the. 245 - these should be connected to ground rather than left unconnected.

    Please can you explain that with more details. I don't understand that. Is my connection to the Levelshifter O.K.?

    Sorry for my bad english.
     
  11. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    3OE, 3A, 4OE and 4A are input pins on the chip that you don't have a use for.

    74HCT devices like nearly all CMOS chips have very sensitive inputs.
    So sensitive that they pick up RF interference causing the chip outputs to oscillate wildly.

    The fix ? Just connect them to vcc or ground.
     
    • Like Like x 1
  12. darkside40

    darkside40 New Member

    Messages:
    23
    Hardware:
    RPi1/Zero, 32/64bit, +nodeMCU/ESP8266
  13. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Yes - well my own mosfet equivalent.

    They work but I found I needed a much lower pull-up on the 5v side.
    An open collector style driver will
    Never be as good as a push pull output like a 74hct has
     
  14. darkside40

    darkside40 New Member

    Messages:
    23
    Hardware:
    RPi1/Zero, 32/64bit, +nodeMCU/ESP8266
    Okay, thanks for the Info than i will source the 74HCT and bring everything together on some kind of DIY PCB.
    Btw the last picture that Kollektiv02 postet is the correct wiring? Is 1A and 2A connectec to the NodeMCU or to the LED Stripe?
     
  15. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    The "A" pins are inpits so go to the nodemcu.
    "Y" are outputs so go to the LEDs
     
    • Thank you Thank you x 1