I am planning to build a custom keyboard, using a pro micro and QMK firmware, and on my plan there would be an excess of 3 PWM pin. So I thought I can maybe put RGB leds on it on parallel. But the problem is how, it is just possible that I will just wired them on parallel, then it will work or I need to put some resistor or diodes on it? Also IF I want to control its brightness what should i need?

I will appreciate any advice will come, thanks.

BTW I don't have the parts for now so I cant test it. I am on the process of sourcing the part on where to buy for it.

I hope this is the right place to ask about this, please forgive I am very new in electronic, I just need some guidance.


Pro Micro Link to Aliexpress.

I am planning to put 7 individual LEDs or if possible I will put 15 or 25 LEDs so all the keys has LEDs

  • \$\begingroup\$ There is some essential data missing: A "pro micro" what? How many RGB LEDs, strip or individual LEDs? \$\endgroup\$
    – MatsK
    Sep 10, 2017 at 3:24
  • \$\begingroup\$ @MatsK I added link to the "pro mico" basically it was a clone from Sparkfun, for arduino controllers, but most of the custom and cheap keyboard use this cloned microcontroller. Thanks. \$\endgroup\$
    – zer09
    Sep 10, 2017 at 4:40

1 Answer 1


You would want to add the resistors for a single typical 20mA rgb led on a 5v or 3.3v microcontroller. Resistors are cheap.

For multiple leds or led strips, you need a more complicated circuit.

  • \$\begingroup\$ Hello I want it for multiple individual LED, about the resistors what kind of resistors should use?"sorry I am not so familiar with them, basically I am just learning by now", do you have a sample schematics for arranging the multiple LEDs? Thanks. \$\endgroup\$
    – zer09
    Sep 10, 2017 at 4:43
  • \$\begingroup\$ Example if I want to use this LEDs from Aliexpress. \$\endgroup\$
    – zer09
    Sep 10, 2017 at 4:46
  • \$\begingroup\$ It also ok to me without controlling the LEDs brightness, as long its lights up. \$\endgroup\$
    – zer09
    Sep 10, 2017 at 6:09
  • \$\begingroup\$ @zer09 common anode or common cathode means you have to wire them all up in parallel, with a resistor for each color. Easiest is common anode, and a transistor or mosfet for each color. \$\endgroup\$
    – Passerby
    Sep 10, 2017 at 6:16
  • \$\begingroup\$ @zer09 see this question for example schematic and setup electronics.stackexchange.com/questions/65996/… \$\endgroup\$
    – Passerby
    Sep 10, 2017 at 6:17

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