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Other APA102 leds not working, some questions

Discussion in 'LED Devices Support' started by David Hequet, 15 January 2020.

  1. David Hequet

    David Hequet New Member

    Messages:
    6
    Hardware:
    RPi3
    Hi,

    First, sorry for bad english, i'm french :)

    I started my hyperion project some month ago and it didn't work. Forgot it, and now i'm retrying to make it work.

    I followed this basic tutorial with a small led stripe (54 leds) : https://hyperion-project.org/threads/raspberry-pi-3-mediacenter-hyperion-ambilight-no-soldering.77/

    Some leds light up when i plug the AC adaptor, with or without raspeberry..

    I tested the SPI (loopback), tried another raspberry (tried with pi 3b and pi 0W)
    I tested a HCT125 level shifter..

    So i decided to go back to the basic and installed a fresh rasbian, this library https://github.com/tinue/apa102-pi and same results: some led light up, but no control.

    With a friend we decided to measure tension in the led stripe and i don't know if this is normal:

    Without wiring CI and DI to the PI (only power) we measured approx 4.2V on the CI band, one every two. and 0V on the other one. Does anyone know if it is this the normal way the led stripe work?
    upload_2020-1-15_17-15-26.png

    Do you have another idea i can test?

    Thank you
     
  2. Akriss

    Akriss Active Member

    Messages:
    537
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Hi,
    Just checking if you have enabled the SPI bus on the Rpi? You did not mention enabling it.

    Reference: https://www.raspberrypi.org/documentation/hardware/raspberrypi/spi/README.md

    excerpt:
    "
    Code:
    The SPI master driver is disabled by default on Raspbian. 
    To enable it, use raspi-config, or ensure the line dtparam=spi=on isn't commented out in /boot/config.txt, and reboot.
    If the SPI driver was loaded, you should see the device /dev/spidev0.0.
    "

    Hope it's of help.
     
  3. David Hequet

    David Hequet New Member

    Messages:
    6
    Hardware:
    RPi3
  4. Akriss

    Akriss Active Member

    Messages:
    537
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Some things I do to test.

    Shorten the wire for DI and CI that attach to pin 19 and 23, respectfully. 20cm -/+. Just for testing. Very long wires should use a level shifter.

    Cut the first led on the strip off. It's possible that it's damaged. However I would keep it and use it to test a short wire scenario with it first. And it's easier to work with a small setup at first, till thing work. Or if you know your setup is not using the entire strip. You can cut off 3-4 led's for test purposes.

    Any more pictures of you setup/wiring?
    Someone once said "A picture is worth many words."

    Hope it's helpful.
     
  5. David Hequet

    David Hequet New Member

    Messages:
    6
    Hardware:
    RPi3
    Since it doesnt work i didn't make photo of my setup and didn't use if for my tests.

    I used the rest of my led stripe (54 leds, uncut stripe). The dupont wires measure approx 20-302cm.
    Cutting the first led is a good idea, i will test.

    I tried to a solded somes dupont wires to a level shifter, it's very uggly :)

    Last week i ordered for test a bunch of level shifters, a breadboard and a 1meter APA102 led stripe. Next try when i receive my order.