Is anyone aware of a situation where a addressable smd led will light up green with pos and neg connected, cant seem to get these to change colour. Tried a few libraries with arduino nano and no joy.
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Hi Terry,
It sounds like you’ve run into a tricky situation. To better assist, could you share:
- The wiring diagram you’ve followed.
- The libraries and versions you’ve tried.
- Any error messages you’ve encountered.
- Photos of your setup might also be helpful.
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coinslot_2023-10-27.pdf (62.0 KB)
Ive tried the fastled library and the adafruit neopixel both have same results. Datasheet
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It lights up green when spun 180 degrees to what is stated in the data sheet. But the data line does nothing.
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Hi Terry
Don’t quite get what you mean here, particularly the “spun 180º” bit.
You should have Power Positive (+), Power negative (-) and Data in and out. Self explanatory. The Data line is direction sensitive, that is it means what it says, in and out. If external power (recommended) used the ground connection (negative) should be common between external power source and data source (Arduino, RPi etc).
Cheers Bob
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I aware of how they are supposed to be powered, when spun 180 i meant when soldering the led on the board I accidentally spin it 180 degrees meaning the champher was at the top left and it lit green.
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Then it has likely been destroyed. The chamfer is next to pin 3, DIN. What voltage did you apply when you had it reversed?
What wiring are you using when you test it? You have shown a diagram of what might be a module of some sort, but there’s no indication of how you are connecting power or the MCU. What example sketch are you using?
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Its 5v powered from arduino nano using the fastled library with the strand test sketch. What i showed was a pcb where the led is soldered to. If the led is destroyed why would it light up? On the pcb there are 3 header pins which connect to the nano.
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The device is actually 3 LEDS - you might have destroyed only one or two of them, or perhaps the control logic. You should not try to power the module from the Nano 5V - it doesn’t have the capacity. Find a separate power source, but be sure to connect all the grounds together. How is the module data connected to the Nano and how does that connection relate to the code from the sketch? Is this only one LED in that module that’s not working, or do they all only show the green?
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Ive only soldered 1 single led. Thats why i was using the nano 5v output.
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Hi Terry
Just EXACTLY what have you got. That link you provided shows a strip of 6 LEDs. you can’t only solder 1 as they are all connected together and in fact each “LED” is made up of 3 individual units, 1xRed, 1xGreen and 1xBlue as Jeff pointed out which are illuminated to varying degrees to give you all the colours. Your eye does the mixing.
If you managed to only solder one you may have picked the green one all though I don’t think you can possibly do this. But I don’t know as I don’t know the actual construction and I don’t have one to look at. Also don’t know what your soldering is like so what you actually have is a bit of a mystery at the moment.
Cheers Bob
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What was sent to me was labeled as sk6812 addressable leds. I believe i can solder just 1 if i only declare 1 led in the code. The pcb i have is 6 rows of 3 daisy chained with dout connected to din on the next led. My soldering is not bad if i do say so, using solder paste and a heater to reflow the paste.
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Hi Terry
Still have to guess at what you have got.
Like pulling teeth sometimes
Sounds like you have a stock of addressable less and some PC boards and you have to solder the LEDs in place. If that is the case and you reversed one then as Jeff suggested you might just as well chuck it as it is now an unknown quantity which is something you don’t need if you are experimenting.
If the above is correct you certainly can solder 1 unit on its own (without reversing it) but as Jeff explained this 1 unit is actually 3 LEDs and the built in smarts decode the data to drive the 3 LEDs to make up the required colour.
And you should be able to nominate 1 LED and drive it as a single LED string but it might have to be the first LED in the physical strings I think the data is not connected through and the other LEDs have to be there so the smart bits can pass the data on to the next LED. Like if you install the LED in the third position then there has to be LEDs in position 1 and 2 to pass the data to LED 3 and I think you would have to nominate the string as starting and finishing with LED 3. Be aware that the LEDs might start at zero for the first one, I forget now.
Cheers Bob
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Bob you are correct that the led count in the code starts with 0, but ive used plent of apa106 and ws2812 leds in the same mannor. I havnt used the sk6812 before and unsure if i was given the correct datasheet for the pin labeling.
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Do you mean soldering the LED to the module? That’s only half the story - you haven’t shown how you connected the module to the Nano Perhaps green is the default if there is no data being sent. Without knowing exactly how you have everything connected and the code you are using everything is just guesswork. Also, what happens when you test other examples of the same device?
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The board is connected to the nano with dupont cables. No other sketch examples do anything the leds dont light at all. I suspect i have been given the wrong datasheet from the seller
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If you suspect the supplier has provided the wrong datasheet then the best advice would be to contact the supplier and request the correct datasheet.
If you suspect that the problem might be elsewhere then you need to supply proper responses to the questions that have been asked.
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Hi Jeff
How very true.
Like I have often said. Getting the correct information is like pulling teeth sometimes (nearly always).
I’m out of here.
Cheers Bob
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Ok so it turns out the seller from ebay has confirmed by soldering wires to these pins that this is the correct configuration, which is strange because ive never seen them like this. Anyhow ill order a new pcb and be on my way. Thanks for all the help from everyone.
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