Correct connection of the Level switch on the RPI4

    i don't want to interfere but the schematics isn't quite that good after looking at it closer.


    connect PIN1 3.3volts to LV
    connect from barrel connector/PSU 5 volts to ledstrip 5v and to HV ( if the PI has is own PSU then leave it out, otherwise conect it also to the PSU used for ledstrip/levelshifter)


    use a common ground from PSU to raspi/ledstrip/levelshifter Connect al ground together also inbound and outbound on levelshifter.


    then use Channel A

    Thanks jeroen, that basically sounds like the first setup I had (that TPmodding posted above and reattached here). Would you say this is what I need? It seem to work. However, under Librec Kodi it shows the lightning symbol in top right corner which indicates the board does not get enough power. I have a 5V, 18A PSU so this is why i was inquiring here above alternative wiring. Any idea what causes this? I am using common breadboard jumper cables which i thought should be sufficient to power the Pi4? When plugging in an USB C power adapter in addition the lightning symbol disappears but ideally I like to run both LED's and the board from my 18A PSU. ANy help is much appreciated as I am quiet a novice when it comes to this things.


    Zitat von Dan1984

    Any idea what causes this? I am using common breadboard jumper cables which i thought should be sufficient to power the Pi4?


    The PI4 has USB-C connector, this is power in jack. After this it goes into a circuit that protects the PI against shortage and high currents.
    after this circuit the power is spreaded on the PINs 5volts and GND of the PI.


    the underpower warning is just a ( in most cases) software/hardware bug in the PI, as soon as the Pi is booting OS /running Hyperion then you know its doing his thing.
    i have this warning also from day 1 >> i am using 35Amps 5 volts line from a ATX PSU >> its impossible to get underpower with this ..... still when booting you see that lightningbolt on the screen.
    so i wouldn't be really nervous about that :LOL:


    you see my code in my signature? >> avoid_warnings=1 this is to prevent that lightningbolt warning.



    so in short, test the PI if it runs the OS and Hyperion and you are fine, if you want the undervoltage warning to go then put the above line into config.txt without the #

    Zitat von Dan1984

    When plugging in an USB C power adapter in addition the lightning symbol disappears but ideally I like to run both LED's and the board from my 18A PSU. ANy help is much appreciated as I am quiet a novice when it comes to this things.


    thats the problem with the PI4 > because of USB-C (needs more current then PI3/Pi2) they used this port, the problem is that you mostly can only use the original PSU/powersocketadapter that provides this high current.
    this is because USB-C is smart and "detects" data info of the charger/PSU when the charging amends and knows how much current to draw If there is no data then the current is really low > for instance when you directly stripe a USB-C cable and connect it to a PSU thats not a smartcharging device.



    so i would use that USB-C PSU to power the PI separately, i read a lot of problems with trying to get the PI4 on the same PSU than the rest of the setup.
    I don't have a PI4, however i am wel known with different DC voltages/ common grounds and a lot of stuff because its in my line of profession.
    Use the common ground from your second PSU ( 18 Amps) to at least 2 separate GND pins on the PI4


    Don't use the 5volts PIN on the PI but power everything else from your second PSU, then connect everything on the schematics that you had and it should work.

    I agree with @jeroen warmerdam as he mentioned the USB thing previously an it got stuck in my head as i power mine that way. So i had to do some checks just to make sure I was not victim to that, It just kept niggling away at me so the meter came out.


    Official specs:
    Micro USB / Adapter limits the Pi supply down to 2.4 - 2.5A instead of the official 3A if using the proper type C connector, This is to allow you to use your older pi charges on it. So its semi intelligent, you either get 3A or standard Pi current.


    I ran tests on that earlier and with 2x usb2 devices running and the GPIO in use it pulled a max of 1.6A with both in use, I didn't try charging a smart device I will later to see where it maxes out at.


    In theory you could also run it that way as long as you are not heavily dependant on usb3 devices being used on the pi that would take the total current draw to around the 3A mark.


    All you would need is a spare micro USB cable to sacrifice and a micro to USB-C adapter

    at addition to this this story @davieboy :D


    i had a measurement of my PI3b, powerusage is with only running almost 1 Amps. Then it only boots and runs Hyperion and thats it.
    So if the Pi4 uses more current then its obvious why they decided to go with USB-C port



    i have to say with boosted PI and overclocking ARM on PI3b

    Zitat von Dan1984

    Thanks jeroen, that basically sounds like the first setup I had (that TPmodding posted above and reattached here). Would you say this is what I need? It seem to work. However, under Librec Kodi it shows the lightning symbol in top right corner which indicates the board does not get enough power. I have a 5V, 18A PSU so this is why i was inquiring here above alternative wiring. Any idea what causes this? I am using common breadboard jumper cables which i thought should be sufficient to power the Pi4? When plugging in an USB C power adapter in addition the lightning symbol disappears but ideally I like to run both LED's and the board from my 18A PSU. ANy help is much appreciated as I am quiet a novice when it comes to this things.



    Thanks guys for all the good answers. I must admit though I'm a bit overwhelmed with guidance in written form as how to best wire my pi4 with the level shifter and apa102 strip. Adding to the confusion is that they are so many different wiring diagrams on this forum. Now it also sounds like I should not run LED and board from my 18 A PSu but use the separate USBC charger for the board (even though tpmodding draw a diagram extra for that purpose-it still is my preferred setup unless the common recommendation is not to). Would it be too much to ask if one of you could draw me a final diagram in how to best connect the pi4 to levelshifter and apa102 strip? As said I don't have much experience when it comes to electrical engineering and I don't want to break anything. Any help is much appreciated.


    Totally man, Just thought you'd of appreciated some Pi4 figures, Id imagine you'd need to be running 2x USB3 hard drives or smart charging as you mentioned to pull anywhere near the 3A, mine was peaking at the 1.6 with video grabber.


    I will vacate now :) just thought it was worth a mention.

    Zitat von Dan1984

    Thanks guys for all the good answers. I must admit though I'm a bit overwhelmed with guidance in written form as how to best wire my pi4 with the level shifter and apa102 strip.



    okay, in short.


    1. use the ledstrip WITHOUT levelshifter, connect PIN 19 to Data and 23 to CLK on the ledstrip ( works most of the times.)
    if not follow 2....




    2. use the ledstrip WITH levelshifter schematics from TPmodding, connect everything the same and
    use the PI4 own PSU with USB-C connector.

    Thanks Jeroen. I thought I Def need a level shifter for the data wires.?


    If I use the raspberries own USBC PSU in addition can I not loose any wires in tpmoddings diagram since his wiring setup also has the pi4 powered from the same source? I do not want any unnecessary wires.


    Zitat von Dan1984

    I thought I Def need a level shifter for the data wires.?


    no, you only need this when the ledstrip doesn't want to fire up :)


    It has to do with a dataline that is to low sometimes from GPIO to the ledstrip to recognize,
    mostly you can correct this/undermine this problem with a good/clean and steady DC PSU.
    APA102 normally don't really need a levelshifter so if possible and you don't need it in your setup then leave it out i would say.


    it can't do harm if you use it or don't use it, just a precaution making sure dataflo is coming from GPIO to the ledstrip. thats all :classy::bigsmile:

    Zitat von Dan1984

    If I use the raspberries own USBC PSU in addition can I not loose any wires in tpmoddings diagram since his wiring setup also has the pi4 powered from the same source? I do not want any unnecessary wires.


    only leave out the 5volts PIN 2 and PIN 4 from the PI to PSU and logic shifter HV, you dont need that wires



    instead, then connect HV solderpoint to your big PSU 18Amps +5volts


    connect;


    PIN1 3.3volts to LV
    PSU +5volt to HV
    2 ground PINs from PI to low voltage side of GND logic converter
    1 GND high voltage side to ledstrip and PSU
    HV to +5volts VCC ledstrip



    data and clock according schematics of TPmodding, so PIN 19 and 23 in and out of logic level shifter.
    LV to HV direction and you should be fine

    Thanks so much Jeroen, much obliged. This works!! If you allow me some follow up questions so i just "understand" better why I did this:


    (1) For a basic functionality and given that the Pi is now powered by its own charger I would have assumed that I only need two wires from the Pi to the LED's, namely the clocking and data wire. The LED strip would then just need a GND and +5V from the second PSU (18A). In principal I would have thought this is enough for it work. So (a) What is the reason for additionally having the LEDs connected with the ground pins on the pi board and (b) what is the reason to have the 18A PSU 5V+ connected to the 3.3V of the Pi board (i thought the Pi is now being powered by its own charger)?


    (2) What is the reason people here do not recommend to have the Pi powered by the same PSU as the LED's. Ideally I would still like to work with just the one PSU. What Pins on the Pi would i need to hook up with a positive and negative wire from the PSU to power the Pi without the USBC charger (just for my own understanding)?


    Many thanks for all the help, i really do appreciate it a lot!


    Zitat von jeroen warmerdam

    can you make it with this?


    let us know if the thing works :thumbup:

    Zitat von Dan1984

    What is the reason for additionally having the LEDs connected with the ground pins on the pi board and (b) what is the reason to have the 18A PSU 5V+ connected to the 3.3V of the Pi board (i thought the Pi is now being powered by its own charger)?


    the reason is that you never can have to much grounds, the more the better.


    The PI is not being powered on PIN1 but it powers up the logic level shifter on LV input.
    the converter then "knows" what it has to do with the channels you can say. Between LV and HV the converter sets his output on the channel.
    A level converter you can also use to increase instead of decrease data lines, just connect the device at the other end. Its called bi-directional.


    Zitat von Dan1984

    What is the reason people here do not recommend to have the Pi powered by the same PSU as the LED's. Ideally I would still like to work with just the one PSU. What Pins on the Pi would i need to hook up with a positive and negative wire from the PSU to power the Pi without the USBC charger (just for my own understanding)?


    I doesn't really matter that much and its more a preference to power individually or everything together.
    Most important thing is this; especially when used more then one PSU then grounding becomes life important between the devices and the PSU's.
    ledstrips are really sensitive for bad grounding or bad PSU's and connections


    your last question is a good one, yes you can power the PI directly on the powerPIN 5volt and GND on the PI, u can use PIN 2/4 for 5volts and 6/9/20/25 and so on for GND. Should u power the PI like this? thats a good question because in this way you evade the electronical circuit that protects the PI for shortage/mallfunctioning and and such. Do i think this is a good way to go? yes and no, first i would try with original USB power port of the PI>> if that would all fail then yes then i would use directly the power PIN.


    I have it connected with only one really powerfull PSU of 35 Amps on 5volts, using the original USB port of the PI3b on that same PSU.
    the only problem is now that with the PI4 the USB port expects' a high current it can draw, so when thats not possible because of using bad PSU or whatever then you get undervoltage warnings and a PI4 that wouldn't run good.
    For this i make an exception and say then yes, power the PI4 on USB-C with a SEPARATE PSU :rolleyes:

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