Devantech SRF01 Sonar Rangefinder
The Devantech SRF01 is the world’s smallest single transducer ultrasonic rangefinder. It’s got a single pin serial interface connection. The SRF01 can measure in cm or Inches. In standard mode the SRF01 measures from approx 18cm (7in) to 600cm (19ft). In Advanced mode it is possible for the SRF01 to measure range all the way down to zero.