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.