How do the Analog Inputs work?

What do the analog inputs measure? (voltage? resistance?) I’m assuming voltage, but I don’t know if I’m right. I am a newbie so I don’t know much about the brain, but that is my job. I’m trying to make IR sensors to detect which angle the beacon is in relation to the 'bot. Please help.

There are analog inputs on both the OI and the robot controler, I am assuming you are asking about the ones on the Robot controler.
They measure voltage, have 10 bit resoultion, and a 0 to 5 volt range, you can code to drop the resoultion to 8 bits. Full info on how to code and such can be found in the progamming instructions and by searching the fourms here.
Good luck Biff

Thanks, I wanted to confirm my suspicion.

There are two different questions here. Biff answered about analog inputs, however, that doesn’t help you get the IR beacons working.

The IR beacons emit IR pulses at a specified frequency. In essence, they turn on and off at a specific rate, a digital signal. When you see the beacon, you see that frequency, otherwise you don’t see the beacon. If you want to find the beacon, you must rotate your sensor until it detects the frequency. You can do this by connecting it to a servo or motor, or you can rotate your entire robot.

Kevin Watson has posted some example code for handling the IR sensors. If you want to see all of his neat programs, his main site is

His code uses 4 infrared sensors and 2 servos. If you don’t want to get that complicated, you should at least look at how he detects the signal.