Best posts made by Neil Manuel

@crispyoz is there a specific reason you have calculated 15mA drive for the LEDs?
A lot of first timers look at the 20mA current ratings for a LED, calculate the resistance for it, power it up and wonder why its lighting the whole room!
The reason I ask is because I have found, in practice, with currently efficient LEDs you can get an appreciable light output with a mere 5mA or even less. If you reduced the current to each LED to, say, 4mA I'm sure that an 8mA draw from each GPIO pin is then quite do-able without releasing the magic blue smoke.
If you experiment with a 3.3v supply and some resistors you can find a point at which the LED is bright enough whilst drawing minimal current.