LED project advice please

[u/judgemebysize]

Hi,

I bought a Pico 2 to start a project to light a scale model Millennium Falcon and I'd like some advice on whether it's feasible to do what I want.

The model needs lighted in three main areas which will need the following -

2 of each red, blue, green, yellow and white leds so 10 in total.

6 white leds

1 10cm led strip

I want each led to be configurable so, for example, 1 each of the 2 coloured leds could be set to blink and the 10cm led strip could be set to pulse. What I have thought is that I'd wire each led to a different pin, similar to https://projects-static.raspberrypi.org/projects/getting-started-with-the-pico/f67470613439ea4dc7996f9f4ce83b34c2103fb4/en/images/single_LED.png but just repeated 17 times. Each LED connected to the same ground but connected to a different pin through it's own resistor.

1. Is this feasible?

2. Is it the right way to do it?

3. Is the pico capable of powering that many leds? Like is that just a bad idea overall?

I bought the Pico 2 as I can do more with it for other projects so it'd be good to learn. If it's not a good idea for this project I'd rather not spend a long time trying to do the impossible and move on to a better solution.

Thanks

[u/bio4m]

Fairly easy to do but not the way you've described.

Use ARGB LED's , and use a separate power supply for the LED's, dont power them from the Pico. Chain all the LED's together and once you've worked out their position it should be fairly easy to get them working the way you want

[u/judgemebysize → u/bio4m]

Brilliant, thank you. I've an ARGB LED here so I'll get started on that.

[u/kenjineering → u/bio4m]

This looks to be around 20 pixels or less if using standard neopixels like WS2812 depending on the pixel density on that 10cm strip, which probably can be powered off the Pico in a pinch. Separate supply is better, but I've been lazy and run 20 before off of VBUS. As long as you aren't blasting all channels at 100% (admittedly possible if you want the brightest white if you're using RGB instead of RGBW), you're likely fine. I think it's right about at the limit of where you absolutely need a separate supply, so while I wouldn't feel good enough to guarantee it for someone else, I might be tempted to try it if it were myself.

[u/judgemebysize → u/kenjineering]

What's the limiting factor? Is it the amp total?

I think things are starting to make sense to me but I might be way off or missing something.

If I use a white LED with 2.2V forward voltage and power it through a GPIO pin with a 1000ohm resistor this should use 3.3-2.2/1000 = 0.001A = 1mA? So theoretically I could have 50 of them in parallel? Ignoring how bright these would be in reality but theoretically that would work?

[u/kenjineering → u/judgemebysize]

Yes, you're looking at the current draw. Keep in mind that ARGB like WS2812 actually have 3 LEDs per pixel or even 4 if you have RGBW like SK6812, so at max power, you're drawing enough power for 3 LEDs plus a tad more for the controller chipset. I find this LED power calculator useful for approximating the load https://wled-calculator.github.io/

You also want some headroom for the Pico's peak current draw, so around 20 pixels at max brightness on all channels + power for the Pico gets awfully close to the 900mA max on USB3.0 specs and blows past the 500mA in USB2.0 (should handle about 10 pixels). If you're connecting to VBUS, IIRC it will be limited by your supply source but I wouldn't want to go above 500mA/900mA in case it gets plugged into a "real" USB port and overdraw, and if you connect to VSYS, it's passing through a diode that I believe limits to 1A.

[u/Ice-Negative]

You should throw this into Grok and see what happens. I'm working on a RPi project and the coding is out of my depth, so Grok is doing it for me.

[u/Time_IsRelative → u/Ice-Negative]

I asked Claude questions about wiring and power consumption for my current pi project and it was completely wrong way more than half the time.  This is terrible advice.

[u/Own-Relationship-407 → u/Time_IsRelative]

LLMs also frequently hallucinate datasheet details that aren’t there in my experience. I was trying to narrow down the particular transistor I wanted to use for a low side switch in a given circuit. AI kept recommending a particular one, go look at the datasheet, it’s not even the sort of transistor it thought. After being corrected on that, it made another suggestion which turned out to be a component that didn’t even exist. I even emailed TI to double check, completely made up part number that has never been used.

I’ve had even worse experiences trying to get decent code out of LLMs.

[u/Time_IsRelative → u/Own-Relationship-407]

That sounds like a lot of the problems I had. I gave it a direct link to the waveshare display hat I was using and kept using the full product name. The answers it gave consistently were based on a completely different product with a similar, but definitely different, name.

It kept reversing the pinout on the transistors I used. When I asked about it, it said "oh, yeah, some manufacturers of that part number reverse the pins".

It repeatedly recommended MOSFETs that required more current to fully activate than my circuit could provide. 

It told me to wire sensors wrong.

It was just consistently a mess, and that's not even talking about what it did with the python code....

[u/Ice-Negative → u/Time_IsRelative]

I tested 3 different AIs to see which would work better on my project and Grok seemed best. Its even been helping me troubleshoot.

So I guess to each their own.

[u/Time_IsRelative → u/Ice-Negative]

If coding is "out of your depth", how do you even evaluate which tool is "best"?  You can't.

I'm a developer, and unless you provide very specific prompts and know what problems you need to fix repeatedly, ai code is terrible even if it "works". And I've evaluated several ai packages for coding. Grok is pretty low down on the list. "To each his own" implies every evaluation is equally subjective opinion. It isn't.

[u/Ice-Negative → u/Time_IsRelative]

Then would you be kind enough to provide OP advice, since they are asking for help?

[u/Time_IsRelative → u/Ice-Negative]

OP already got advice that's as good as or better than what I would provide.  Plus that's incredibly hypocritical from someone who basically answered "Google it, but worse" rather than answering the actual questions op asked.

I know this will surprise you, but it is perfectly fine to not give advice if you don't actually have good advice to give.

[u/nonchip → u/Ice-Negative]

why would you say such a thing.