Electronics > Beginners

Want to control 12 LEDs but there is not enough pins on Arduino?

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Dabbot:

--- Quote from: james_s on July 22, 2019, 12:56:45 am ---With only 12 LEDs I'd be tempted to just multiplex or charlieplex them directly. If you wanted to drive a larger number of LEDs the MAX7219 can handle 64 of them from just a few IO pins.

--- End quote ---

What is with the pricing for these chips?
Digikey / Mouser / element14: $15
Jaycar: $5 :o

TLC5916 is approaching something more reasonable.

mariush:
You can still buy LED171596ARSLR (96 channel led driver) for 8$ : https://www.digikey.com/product-detail/en/texas-instruments/LED171596ARSLR/296-51223-1-ND/9745587

48 channel drivers are cheap at 4$ each or ~2.5$ each in 1000pcs, see for example TLC5954 : https://www.digikey.com/product-detail/en/texas-instruments/TLC5954RTQR/296-40587-1-ND/5178464

You can chain these or give each one unique i2c address ... no problem.

The Jaycar chips are most likely very old stock or they're clones/fakes.

Nusa:

--- Quote from: Kjelt on July 22, 2019, 05:19:58 am ---
--- Quote from: Nusa on July 21, 2019, 09:34:40 pm ---A decoder doesn't work so well if you want more than one LED lit at a time, although you can likely cycle it so several appear lit. All of them at once is probably out of the question.

--- End quote ---
The hef4000 were sturdy, IIRC  25mA per output max total 250mA or so, with modern he leds @4 to 6mA it is more then enough, so wouldn't be a problem at all.

--- End quote ---

I think you missed the point. If a decoder has more than one output enabled at a time, it would not be working properly, so there will never be more than one output pin drawing current.

My point was that trying to make them all appear lit at 1/16th (or 1/12th) duty cycle per LED is just asking for unsatisfactory results.

Dabbot:
Go to Banggood and get a WS2812B strip.
Cheap? Yes.
Overkill? Yes.
MCU pins: 1
Interface libs: Written.

NivagSwerdna:
https://playground.arduino.cc/Main/MAX72XXHardware/ provides easy control of up to 64 LEDs.... or go with the NeoPixels if you want colour!  :)

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