Page 304 - ARM Based Microcontroller Projects Using MBED

290 10. USING LIQUID CRYSTAL DISPLAYS (LCDs)

10.4 PROJECT 3—ULTRASONIC HEIGHT MEASUREMENT

10.4.1 Description
Having the correct height is very important especially during the child development ages.
Human height is usually measured using a stadiometer. A stadiometer can be either mechan-
ical or electronic. Most stadiometers are portable, although they can also be wall mounted. A
mechanical stadiometer is commonly used in schools, clinics, hospitals, or doctors’ offices.
This project is about designing a microcontroller-based device to measure the human height
using ultrasonic techniques.
As shown in Fig. 10.9 a mechanical stadiometer consists of a long ruler, preferably
mounted vertically on a wall, with a movable horizontal piece that rests on the head of the
person whose height is being measured. The height is then read on the ruler corresponding
to the point of the horizontal piece. Using such devices the height can be measured from about
14–200cm with graduations of 0.1cm.
In this project we will see how to design of an electronic stadiometer based on the principle
of ultrasonic waves.

10.4.2 Aim

The aim of this project is to show how an ultrasonic height measurement device can be
designed using Mbed and the Nucleo-F411RE development board.

FIG. 10.9 Mechanical stadiometer.