There are quite a few distant meters made with Arduino, but this is a special one.Two reasons why this is special: First because it's made with a 328P chip with boot loader; Second because it has a push button that allows to give you in real time the delta distance of a measure.

Let me explain how it works:

• When switched on, the meter measures the centimeters distance from the meeter to the front obstacle.
• At that point, pressing the push button, the meter does a reset to zero and moving it from the obstacle it measures the delta distance.
• The distance can be positive or negative depending if you move the meeter closer of farer to the obstacle.
• The push button can be pressed at any time to reset the delta measure.

This function is handy for several applications. One of them is the measure of your height. I've applied to the device an old swipe card to the bottom that can be used to fix the device to the door frame. Look at the video for an example.

?