Hi ciabio,You can definitely hookup two leds on one digital pin, don't forget to put a resistor in series with the led to prevent damaging them. So for section one you would need 16 digital pins. For section two, if you want to do what you are doing in the GIF , you would need a pin for every led (so 16).A teensy 3.2 has 34 digital pins (some shared with analog) so you should be fine. Hope that helps
so for section one use one resistor per two LED's
The reason you need a resistor is that the LED usually can't handle the power (voltage X current) the digital pins provides to it.
The value of the resistor depends on the LED you are using, you can easily calculate it by looking up the max power of the LED and the current and voltage output of the digital pins.
No No No.No apostrophe needed in LEDs but more importantly you need one resistor on each LED because LEDs in parallel do not share current equally.No it is the current not the power, LEDs are a non linear device and do not obey ohms law.That is not a quality answer.The total current from one Arduino output pin should not exceed 30mA, anything over 40mA damages the processor. So you can't run two LEDs from one pin @ 20mA each. Anyway that would probably be too bright to look at directly so calculate the resistor for a 10mA current.However before you can calculate the resistor you need to know the forward voltage drop of the LED, if you don't have a data sheet you will have to measure it.
the current voltage from the white led are 2.8-3.6
its not an arduino but a teensy 3.6
But what about the maximum voltage of 3V3, a white led is not very bright at that voltage in my experience.
Ahhh, the Teensy 3.6 is ofcourse a 3.3volt processor.Not a good choice for white LEDs.Drive transistors and a 5volt supply then (post#7), or a 5volt Arduino.Leo..
the only solution is to add external hardware