Dual output 555 circuit

[raitl]

Hello.

I am making an IR obstacle detection circuit based on a 555 timer. I need to add a second IR LED to the schematic but with the option to turn the two LED's on and off independently, via a single I/O from my uC.

I was thinking of using an inverter chip, but I wish to keep the size of my board to absolutely minimum.

I have attatched my current schematic for a single LED circuit.

 

[user_88]

Independent control of two IR LEDs suggests that there are 4 possible states that you require .... using the single controller output line.
Consider using a binary counter ... of the sort given here:
**broken link removed**
.... using only two flip-flops to construct A and B responses for a count pulse up to 3.

Does this achieve your objective? .... You would have to cycle through the states to get to a desired LED selection ... but that shouldn't be a major problem.

Using only an inverter would not give you a complete selection of LED states.

If this doesn't meet your requirements ... please elaborate.