Future Button and LED software spec

[Werner Almesberger]

I wrote:
> Fortunately, these power-draining LEDs

By the way, since there's been some confusion about what this really
means: the LED circuit only drains power when LEDs are lit.

The bug is that the base resistors were forgotten on the NPN
transistors controlling power to the LEDs. (Yeah, stupid mistake, and
even more stupid of all of us overlooking it for some 9-10 months.)

So when a LED is lit, the transistor effectively shorts the GPIO to
ground, drawing excessive current. When the LEDs are off, nothing
untoward happens.

- Werner