One of the labs for my Microprocessor Based System Design class involved making an electric cane for the blind. The cane worked by first taking measurements from an HC-SR04 sonar sensor. The range of the nearest object could be found by measuring the time from an initial pulse to a returning pulse.

Feedback was then sent to the user depending on the distance of the object. The device had two methods for creating feedback: a small vibrating motor and a small speaker. The closer the object was then the faster the feedback provided.