I’m building a board with locations that have LED flashing lights that flash for a duration there is three different colors. I probably have 100 how can I control those and the duration of flash? Thanks for your help in advance
Easiest way would be to use addressable LEDs like ws2812.
If that's not an option, and you already have the LEDs installed, I think we need more information. Like a link to the specs of the LEDs, an upper estimate of how many there will be, and how many LEDs will be lit at the same time.
Assuming only one led flashes at a time and there are 120 of them, this could be done with a technique called charlieplexing, which would require 12 Arduino pins and 12 resistors.
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100 LEDs? how big is the board ?
Agree with @PaulRB - addressable LEDs like neopixels or APA102 or similar would make your life easier.
Would a strip of LEDs works for your needs or are the LEDs really scattered in many places ?
A picture of what you have in mind would help too.
Start with the blink sketch. Then just change that to change the flash duration. Now look at the BlinkWithotDelay under samples Digital. Now scale up.
Ok, you won't need those additional resistors I mentioned.
Presumably it's something appropriate for the LED's maximum current at the specified voltage. You don't need to worry about it.
with such LEDs indeed we can assume that the bump in the heat shrink black tube is where a suitable resistor is soldered.
but your arduino does not have 100 pins nor the power to drive 100 of those directly from the pins, so you will need some sort of control circuit .
You might be better off daisy chaining addressable leds.
see this example
Perhaps you can use a LED driver such as the TM1680 to do the charlieplexing for you?
It can drive 24x16 LEDs, so that means 8x16=128 RGB LEDs is doable. One advantage is that using such a chip could be cheaper than using addressable LEDs; disadvantage might be that the TM1680 only supports setting brightness for all LEDs, not for each individual LED.
Of course there are probably other similar chips, but I'm not familiar with them, so I can't suggest alternatives.
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