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RPi + OpenELEC APA102 5 meters length

Discussion in 'Hardware Support' started by Katak, 30 November 2018.

  1. Katak

    Katak New Member

    Messages:
    5
    Hardware:
    RPi1/Zero
    Hello,

    I ordered a 5m led for my 70" TV, I was wondering if I could supply the whole stuff or if I needed to add supply wires in the middle to ensure all the leds are correctly supplied ?

    Do you have any topic dealing with power supply VS LED length ? :)

    Thanks,

    Katak
     
  2. Lethargik

    Lethargik New Member

    Messages:
    14
    Hardware:
    RPi1/Zero, RPi2, +Arduino, +PhilipsHue
    Hi Katak,

    There is lots of information out there but a couple things I can tell you (apologies in advance, I'm pretty longwinded in my responses):

    A strip this long will need power from more than one end. Typically, people will cut the strip into four pieces (one for each side of the TV) and connect power to each piece - this is what I did for my build.

    Also, a very important distinction is that length doesn't determine your power needs, the number of LEDs does. LED strips typically come in either 30, 60 or 144 LEDs per meter; meaning you'll end up with very different (and potentially unsafe) power requirements if considering only length.

    The general rule is that one RGB LED requires 60mA at full brightness/white, so using 0.06 x # of LEDs you can determine the amperage needed:

    If your 5 meter strip is 60 LEDs per meter, 0.06 x 300 LEDs = 18 Amps (keep in mind you'll need to factor in the power needs of any other components you plan to power from the same power supply).

    It is also important to consider some "overhead" when buying a power supply; for example, if you need 19A, buy a 25A or 30A power supply to leave some breathing room. Your load (devices being powered) will only draw the amount of Amps they need, and your power supply won't have to work as hard if it's capable of 25A or 30A but only has to supply 19A.

    In terms of Voltage, make sure your power supply Voltage matches that of your LEDs and other components. This should be 5V, but you'll want to check all your components to be sure.

    Hopefully this is helpful! Beyond that, just double check your values and keep doing your research (in addition to this site, the adafruit and arduino sites/forums have great info). If you have other questions, I'm happy to answer them if I can - good luck!
     
    • Like Like x 1
  3. Katak

    Katak New Member

    Messages:
    5
    Hardware:
    RPi1/Zero
    Hello Lethargik,

    I assume you do not bear your surname... Wow great feedback, cystal clear and professional, thanks a lot !

    I have been too much synthetic... sorry I was working when I posted this topic.

    Below some information of what I have forecasted / done / bought:
    - TV 70" => 5 meters needed
    - 5 meters LED APA102 5V bought, 60 LEDS per meter => I have hesitated with 144/m but looking at consumption and "over-specification" I did not
    - I made an estimation of 20 A for the whole setup
    - As per the PC PSU I was targeting the area 60% of load hence I bought a 30A DC 5V PS
    - I bought this: https://www.amazon.com/L-Shape-Connector-Connectors-Solderless-Adapter/dp/B0762H4FT1
    - Just for information I bought an amazon IR remote with a relay module to shutdown the whole thing if I don't like it... ^_^ (never tried)

    I am now wondering how I can plug my wires on each angle... I mean you do need the SPI feature so you can't avoid the angle connectors...
    => How do you connect the supply on each ? you solder wires directly on the belt / tape just before or after the connector ?

    If you going through south of France I'll pay you a beer for sure ! :)

    Have a great day / evening
     
  4. Lethargik

    Lethargik New Member

    Messages:
    14
    Hardware:
    RPi1/Zero, RPi2, +Arduino, +PhilipsHue
    Thank you Katak, happy to help!

    I also used APA102 60/M LEDs. APA102 is generally considered the better choice for ease of use and 60 LED per meter seems to be considered the "sweet spot"; better lighting than 30/m but without the large power requirements of 144/m as you mentioned.

    Based on your new information it sounds like you have a pretty good idea of what you're doing:
    - It might be close, but 5 meters of LED should work for a 70" TV. I have mine on a 65" TV and it used 256 out of 300 LEDs.
    - I made the same estimate and also purchased a 5V DC 30A PSU (power for LEDs and RPi Zero W)

    In terms of the solderless connections, they will work, but they can be unreliable as they tend to come loose over time and create a poor connection. Soldering, done properly of course, will always be a better connection than this. Since you'll need to solder additional wires for power anyway, you might consider just soldering all connections, though that is obviously your decision based on what you're comfortable with - you can certainly use the corner clips you've bought and just solder on power wires a few points along the strips if you prefer.

    In terms of how to add power and connect clock and data for SPI:

    I just moved, so my build is in pieces and I was able to take a few photos of what I did with my setup that I hope will help you. I've also drawn a quick sketch, just to give you a general idea of the overall layout of how I connected things - for the record I am clearly NOT an artist, haha.






    - You may already be familiar, but if not the orange and grey splitter/connectors I've used for my wiring are called "Wago Clips" or "lever nuts" and I highly recommend them.
    - For the wire itself, make sure to choose a gauge of wire rated for your amperage.
    - keep clock and data wires as short as possible if connecting RPi to LEDs without a level shifter (shorter is always better here, under 30cm if possible - I learned this the hard way).

    I'm not sure how clear these photos will be, so if anything is confusing, please ask and I'll try to clarify.

    Cheers!
     
  5. Katak

    Katak New Member

    Messages:
    5
    Hardware:
    RPi1/Zero
    Hey Lethargik !

    Thnaks again for this great support, all my questions have been totally answered and now I'll take time to prepare the whole thing.
    I'll try to find these wago connectors, look really useful ! :)

    I bought this device with UTV007 chipset, I hope it will be compliant with raspberry.
    https://www.ebay.com/itm/282995512012

    How did you learn the hard way that short wires were mandatory ? :-/

    Kind regards,

    Katak

    PS: btw I'm using a RPI 1 with video grabber, an AVR will allow me to avoid a splitter.
     
    Last edited: 1 December 2018
  6. Lethargik

    Lethargik New Member

    Messages:
    14
    Hardware:
    RPi1/Zero, RPi2, +Arduino, +PhilipsHue
    Hi Katak,

    UTV007 is the correct chipset for the grabber so that should be fine.

    As for the RPi 1, you may consider moving up to a RPi 2, 3 or Zero W if you have trouble with it. I can't say that you will, but I feel like I read some information when researching my build that RPi 1 was often problematic for these ambilight setups. It's just a gut feeling I have, so I could certainly be wrong but wanted to mention it just in case.

    As for the short wires... haha. I setup my build with clock and data wires about 120cm long and my lights would flicker like crazy. The reason is a combination of voltage drop and that the RPi (all of them) put out clock and data signals at 3.3v but the 5v LED strips expect a 5v signal (this is why people use level shifters; to convert the 3.3v signal up to 5v from the pi to the LED). On a very short wire, the 3.3v is generally strong enough to work properly, but longer wires have more voltage drop (and the data and clock wires from the pi are very small) so the already low voltage gets further reduced and causes sporadic behavior with the LEDs. As a general rule with your build, the shorter any and all wires can be, the better.

    Good luck!:)
     
  7. Katak

    Katak New Member

    Messages:
    5
    Hardware:
    RPi1/Zero
    thanks for your feedback, I bought the RPI zero WH since the price is quite low. I do the issue, it concerns VIH as per electronic understanding; do we have a solution compliant and easy with RPI ?

    I'm saying that because I bought the grabber and converter a week ago and I've discovered yesterday an App the may be run on Android system that can provide data to hyperion... Great idea :)

    One question, what is your feedback on ambilight ? may you watch a movie without the system ? ^^

    Have a good afternoon,

    Katak
     
  8. Katak

    Katak New Member

    Messages:
    5
    Hardware:
    RPi1/Zero