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Check LPD8806 strip for correct function

Discussion in 'Hardware Support' started by ph0x, 16 April 2020.

  1. ph0x

    ph0x 1337 h4xx0r

    Messages:
    8
    Hardware:
    RPi1/Zero
    Hello!
    I produced an ambilight setup a few years ago with a Pi1, a Fushicai USB007, a Chinese LPD8806 strip and ambi-tv from gkaindl. Everything went quite fine until (after a move) the setup stopped working. I blamed the SDcard and decided to check as soon as I find the time.
    Now that Corona has us at home, I installed a new Raspbian and Hyperion (still on the Pi1) but the led strip still showed no action. So I dug into the SPI and GPIO stuff and found out, that the two pins needed for the strip (CLK and MOSI) are faulty, which is usually the case when they received 5 volts, which I think they didn't, but hey ...
    So before I buy a new raspberry and fry the next set of SPI pins I wanted to test that the led strip works as expected.
    I noticed that a few of the smaller parts on the strip (labelled C104) have broken off, but I'm not sure if that affects the function at all. I also found out that after every even segment (where you can cut the strip) there is a 5 volts potential between CLK and DI, and none after the odd segments. Is this normal although there is absolutely no input to these pins?
    Is there a way to tell if the strip is fine?

    Best regards
    Marco
     
  2. TPmodding

    TPmodding Administrator Staff Member Administrator

    Messages:
    1,886
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +nodeMCU/ESP8266
    1. you could try it with an arduino
    2. skip a few leds and input the data to another DI and CLK
     
  3. ph0x

    ph0x 1337 h4xx0r

    Messages:
    8
    Hardware:
    RPi1/Zero
    I hooked some scrap strip parts from then to the power source and it showed the same behaviour, but they might be damaged as well, don't know.
    What's different with the arduino? Is that capable of 5V?
     
  4. TPmodding

    TPmodding Administrator Staff Member Administrator

    Messages:
    1,886
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +nodeMCU/ESP8266
  5. ph0x

    ph0x 1337 h4xx0r

    Messages:
    8
    Hardware:
    RPi1/Zero
    As I already mentioned, i dug into that stuff and, of course, also ran that loopback test. There were only zeros coming back, plus wiringPi's pintest and another tool reported the SPI pins to be damaged. So there's really no doubt about that.
     
  6. TPmodding

    TPmodding Administrator Staff Member Administrator

    Messages:
    1,886
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +nodeMCU/ESP8266
    how did you test the scrap stripe parts? with an arduino you can test if the stripe works
     
  7. ph0x

    ph0x 1337 h4xx0r

    Messages:
    8
    Hardware:
    RPi1/Zero
    The scrap parts brought me on the track that something might be broken, but I did not actually test them, that's right.
    So the Arduino will not break if there is a shortage in the stripe that gives 5 volts to the data input? It works with 5V rather than 3,3V, right?
    Or do you have any hints how to check the stripe aside from trying to make it work? An oscilloscope maybe?
     
  8. ph0x

    ph0x 1337 h4xx0r

    Messages:
    8
    Hardware:
    RPi1/Zero
    Well, with the arduino the stripe worked like a charm, also no overvolts between CLK and DI.
    Maybe I'm lucky and will have a working setup in a few days with the new Pi zero I ordered yesterday.
    Thanks for the input!
     
  9. eMd

    eMd New Member

    Messages:
    27
    You use hyperion.ng or classic hyperion? Hyperion..g alpha6 will not work with lpd8806....
     
  10. Lord-Grey

    Lord-Grey Moderator Staff Member Developer

    Messages:
    247
    Hardware:
    RPi3, 32/64bit
    ... but a fix will be in place with the next release...
     
    • Like Like x 2
  11. eMd

    eMd New Member

    Messages:
    27
    yeah i see your commit from 11.06.2020...i hope this fix will work ;)
     
  12. ph0x

    ph0x 1337 h4xx0r

    Messages:
    8
    Hardware:
    RPi1/Zero
    I use the classic version so I guess there's another problem here. After all of my tests I came to the conclusion that the video grabber is broken since I'm not able to get a signal under any operating system that I use.