Electronic Tape Measure

My Amazon recommendations recently listed an LCD screen for $10 and an ultrasonic range finder for $5. That was too cheap to pass up. The parts came in the mail this past week and I decided to whittle away my Saturday playing with them.

I started by looking at the amazon listing for the device to find instructions.


This was the first time I looked at the product reviews and most people were upset with the LCD because there were no instructions, and sainsmart.com, who sells it, has no docs. In fact, I couldn’t find this exact model even listed on their website. But one person did mention this was an HD44780 LCD screen, so I started researching that.

The sainsmart.com LCD screen turns out to be an industry standard HD44780 LCD screen. Set up instructions, an LCD library, and example code already exist at arduino.cc:


I had to solder a 16pin header onto the board first. Then I set up the LCD exactly as illustrated and put in the sample code. Worked like a charm. I had “Hello World” on the LCD almost immediately (forget to connect 1 wire). No reason to panic.

With the LCD screen running, I moved on to the sainsmart.com ultrasonic range finder:


I went straight to arduino.cc. There is information/code for the similar parallax model, but that device has only 3 pins. Looking at amazon reviews for the device someone mentioned to look at the NewPing library on arduino.cc:


That had information and code examples that work for the sainsmart device. I had it up and running within minutes, with it reporting the distance to an object via the arduino’s serial port.

Now that I had both devices running, why not combine them into something? Of course an electronic measuring device popped into my head immediately (this is hardly an original idea). However, it was simple and I could implement it using the existing code very quickly.

Within 15 minutes I had an eTape Measure up and running:


It is accurately measuring the little black case at 8″ away.

Pretty cool (and fun) for a mornings work.


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