SRF05 Ultrasonic Sensor

Materials list
1) Microcontroller and a way to program it - I used a PIC18F6722 dev board.
2) Way to wire the circuit - I used jumper wires and a solderless breadboard.
3) Way to display the distance measured by the sensor - First I used the RS-232 port to my PC then I used a dual 7 segment display to increase my mobility.
4) The SRF05 Sensor.

Design details

Overall I was immensely impressed with the SRF05 ultrasonic sensor in both its ease of use and accuracy.

The instructions that I got describing its operation made it extremely easy to interface it with my PIC micro controller. Once I had it up and working I was ecstatic with how accurate it was at detecting objects. It seemed to have a range of over 200 inches which is way more than I needed so I did most of my testing at less than 100 inches. At less than 100 inches it seemed to be accurate with 2-3 inches and under 30 inches it seemed to be accurate within an inch or so. I was afraid that it would keep detecting collisions with the floor or a parallel wall, but that didn’t seem to happen. It seems to detect an object you need to make at least a 20 to 30 degree angle with that object in order for the ultrasonic sensors to get a reflection. This could be viewed as a bad thing by some since you could still hit a wall at a low angle, but I like it that I won’t be getting false collision readings. I can always avoid slowly running into a nearly parallel wall by either adding another sensor or adding a movable servo turret for the SRF05 sensor.

You will notice in my circuit diagram below that I hooked up a dual 7 segment display so I could output the distance during testing. This worked fairly well only up to 100 inches since I only had 2 digits, but it took a lot of time to wire up and write the code to run it since it uses so many ports off the micro controller. Next time I do something like this I will probably either use a RS232 port on a laptop or use something like the Parallax 2x16 Serial LCD.

Here is the souce code: source code
Here is the circuit diagrams: SDF05, 7 Segment Display
Here are some pictures: Pic 0, Pic 1

Please email any questions/comments/errors to robots@glacialwanderer.com.