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SOLVED Level shifter

Discussion in 'Hardware Support' started by thommy86, 18 January 2017.

  1. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    What is the correct way to connect a 74hct125?
    I also post this in the Dutch forum, but in English there is a larger public.

    I use a PI3 and apa102 LEDs. I see a lot of different ways, but no concrete answer for me.
    Everything is now connected as discribed on the adafruit forum. But I would still like confirmation before I connect the powersupply.

    Adafruit Forum
    [​IMG]
    Showcase @paddy here on the forum.
    [​IMG]

    I want to separate power for the pi because I use a mausberry. Therefore, the lower figure did not seem right for my application.
    But I am not sure what the difference is between these versions. If someone can confirm these steps, I will edit the wiki so this will be clear to all.

    Almost finished! Work in progress!
    [​IMG]
     
    Last edited: 19 January 2017
  2. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    The top breadboard picture is mostly correct. It should work but the unused inputs should be connected to high or low and not left floating.

    The orange one is totally wrong for you.
    1) it looks like it's for an hct08
    2) it's a pcb artwork so is up side down
     
    • Agree Agree x 1
  3. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    Thank you for your reply!

    I'm not sure what you are saying now. Should I connect the unused input(A4 and A3) pins to ground or to C or Y?

    [​IMG]
     
  4. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    C3, a3, c4 and a4 are all inputs and should be connected to vcc or gnd.

    It doesn't matter which pins go to bcc or ground - just use whatever is closest on your circuit board
     
    • Like Like x 1
  5. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    Thank you very much for your help!
     
  6. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    I don't want to open other threat as I am not sure if my problem is hardware or software. At first all the leds worked if I set a color with the remote. Then made the gap in the bottom a little bit bigger, as this looks nicer for my setup.

    Now there are always 3 leds burning and only the half of the strip works. I also tried another Pi, another IC and checkt all the solder connections (this strip was cut for a smaller tv, so I had to connect in the middle). Still the same effect. There are a few leds in the part that also don't light up. I don't understand the behavior.

    Can someone help me to pin point my problem? Below some pictures to clarify.
    Apa102

    WhatsApp Image 2017-01-30 at 22.45.23.jpeg WhatsApp Image 2017-01-30 at 22.49.46.jpeg
     

    Attached Files:

    Last edited: 30 January 2017
  7. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    Double post
     
  8. TPmodding

    TPmodding Administrator Staff Member Administrator

    Messages:
    1,339
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +nodeMCU/ESP8266
    do you have more leds then you use in your config? (example: 100 leds, but only 95 used in the config)
     
  9. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    No, I updated the config when I cut the strip. I also tried to play with the config file, but still no luck
     
  10. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    I hooked up an Arduino to test the leds and it seems to be a hardware issue. But where to look? I already replaced a "broken" led en then another one will break. I saw some resistors on the strip, why are these? As I cut the strip, I am not sure these are still all in.. And I also don't know how many led there are between them.
     
    Last edited: 1 February 2017
  11. TPmodding

    TPmodding Administrator Staff Member Administrator

    Messages:
    1,339
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +nodeMCU/ESP8266
    if you cut the stripe at the marked area it should be no problem...but where exactly is your hardware issue, at the pi?
     
  12. thommy86

    thommy86 Member

    Messages:
    61
    Hardware:
    RPi1/Zero, RPi2, RPi3, +Arduino, +PhilipsHue
    No not at the Pi. I got the same effect with the Arduino. So the led must be faulty. I am now replacing all the broken leds and check every time I add a part.

    Edit:

    Just to follow up on the issue. After replacing the broken leds, everything is working fine. Not sure how the led got broken, but I'm glad it is fixed now.
     
    Last edited: 5 February 2017