I've developed a smart proximity detector for robotics. A PICAXE-08M flashes two IR LEDs at 40 kHz (one at a time). The 40 kHz IR detector between the IREDs determines if there is a reflection from the IREDs. The PICAXE monitors the output from the detector. Since it knows when it flashed each of the IREDs, it knows which of the IREDs caused the reflection. The IREDs are mounted on the extreme left and right sides of thePCB giving the smart proximity detector the ability to determine if a wall is located on the left side, right side, or across the front of the detector.
Eventually I'll flash the IREDs at different frequencies to determine if the wall is located farther away or closer.
but first, I have to set my wait period between left and right flashes. I don't know how long the detector "remembers" that it saw a reflection.