AVR-Chat

I can't figure this out simply. I'm sure there is a simple solution 
tho'. Chip is the Mega-168 that I want to add an extra function to.

Assume I have either a two or three pin bi-colour LED (ie. either back 
to back LEDs with two pins, or two LEDs with a common pin).

I have a single pin on an AVR processor that can either be LOW, HIGH, 
or Tri-state.

I want to drive the LEDs either both OFF, one on, or the other on, but 
NOT both on.

SO, I have three states the pin can be in, and three states for the 
LED to be in.

I can't figure out a simple circuit to drive the LEDs with just one 
processor pin. Does anyone have any ideas how to do it using no more 
than two transistors? I'm using Vcc=5 Volts and I have a free 2 Volt 
(low current) reference point I can use.

I'd be most appreciative of a solution. BTW, the solution cannot use 
PWM or anything processor intensive. The spare pin is either and ADC 
input or an I/O pin.



Alternative solution: can anyone suggest how I can use the RESET pin 
as an output and still retain ISP capability (this is a QFP part that 
is programmed after assembly).

Peter






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