The Detector:
Radio Shack 276-137 or 276-137B:
Infrared Receiver/Demodulator
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The Radio Shack documentation is sparse. It appears that most of your troubles reading the signal will be stripped out by the device. It appeared to be a metal cube the size of a dice with three signals exiting the bottom: VCC GND VOUT.

The circuit already demodulates the IR carrier frequency so what you get out is the basic logical waveform. That means that while the IR Remote is transmitting 40Khz, your decoder holds its output high for logic level 1. When the IR Remote is not transmitting at 40Khz or if no IR Remote is transmitting at all, the VOUT signal from your decode is low for logic state 0.

This reduces your speed problems though I can't say for sure that Basic 52 will be fast enough.

By the way, you might be able to how the output directly to the micro though it would be wise to run it through a Schmitt triggered buffer to protect the micro. It never hurts to be safe and Radio Shacks specification left a lot of details excluded. Take a look at a 74HCT14 - its a hex Schmitt inverter. Just run the VOUT signal into pin 1, tie pin 2 and 3 together and then run pin 4 to the micro. Apply +5V power to pin 14 and Ground to pin 7.

That op-amp you said you put in between the circuit and the micro probably would be better removed. All signal conditioning is really taken care of inside the detector and my Schmitt buffer suggestion is probably unnecessary.

After you get reasonable results, you'll need to look more closely into what it takes to interpret the logic signal coming from an IR Remote. It will be quite similar to a software uart routine; not a uart driver. This is a routine that follows the logical 1 and 0 signal and times it to figure out where the real bit boundaries are. There are no real dependable shortcuts to this.

Next time, tell us what baud rate you are writing out to the terminal and if you a collecting data and then sending the buffer to the terminal after the buffer is filled, tell us how big the buffer is.

aka j