I want to build a keyboard from scratch which will be illuminated as well (one LED per key/switch). Due to the fact that I don't need some fancy stuff, just turn the LEDs on/off, can I connect entire columns of LEDs per I/O port of the MC, or I should control them intividually as several schematics suggest?

The reason being, I run out of ports sould I connect them individually. I understand that the answer depends on the amaunt of current the LEDs need and each port supports, yet I would like to know if someone has any experience on that.

To be specific, I want to connect at most seven LEDs per port on a Teensy board. I am not sure about the voltage because I haven't decided yet which exactly board to use.

By the way, are there any specific LEDs (color or type) which are brighter than others without consuming much current?

Any opinions would be appreciated.

  • \$\begingroup\$ why do you want to connect the LEDs to the teensy? \$\endgroup\$ Mar 25, 2020 at 2:03
  • \$\begingroup\$ Are there any alternatives? \$\endgroup\$ Mar 25, 2020 at 2:14
  • \$\begingroup\$ probably there are, what is your goal? \$\endgroup\$ Mar 25, 2020 at 2:37
  • \$\begingroup\$ My goal is to use the least possible ports in order to control the LEDs \$\endgroup\$ Mar 25, 2020 at 7:29

1 Answer 1


maybe just unse one GPIO on the teensy to control a transitor that controls all the LEDs.

  • \$\begingroup\$ This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review \$\endgroup\$
    – TonyM
    Mar 25, 2020 at 13:44
  • \$\begingroup\$ @TonyM would you care to elaborate? \$\endgroup\$ Mar 25, 2020 at 20:09

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