[PICgnosis]

We're using Ping))) ultrasonic range finders, a PIC18F4585, and MCP4921 D/A converters. For each sensor, the PIC generates the 2 - 5 us start pulse, times the echo pulse, and sends the timer value to a D/A converter, which is pluggged into analog input on the robot controller. The robot can operate with two sensors, but it's more robust with three (to get a second opinion on the end of the wall).