Eltec 442-3 to Handy Board Example

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Product image for Pyroelectric sensor package

Introduction
Circuit Schematic
Source Code
Comments

Image of Eltec wired to a Handyboard controller.

Introduction

In this example, the Eltec 442-3 sensor package provides human motion information. It is interfaced to the commonly used Handy Board micro-controller. The controller continually polls the detector and displays text indicating the current movement in the field of view of the detector.

Contents

Circuit Schematic

This circuit is extremely simple. The power (Vcc) and ground lines are taken from the Handy Board's analog port and the output of the detector is fed directly to the analog input. This example uses input number 0 but any will do.

Contents

Source Code

This code is written in Interactive C. This code is not meant to be elegant. It is meant only to demonstrate a simple example. Note, the routine name below is "eltec1" not "eltec-1" which is not acceptable to the Interactive C compiler.

void eltec1(void) { int value; while (1) { /* delay to stop the display from flickering */ sleep(0.05); /* the analog port may change, check which one */ /* you are plugged into */ value = analog(0); /* neutral values hover around 128 (~2.5V) */ if (value > 134) { printf("Moving Left\n"); } else { if (value < 122) { printf("Moving Right\n"); } else { printf("Neutral\n"); } } } }

Contents

Comments

This circuit demonstrates several things about the Eltec Pyroelectric detector package. The Sensor is very sensitive. Try this example out in a large room and notice that the detector can pickup a person's movement from quite a distance.

Notice that the detector's output is relative. You can either move in front of the detector or move the detector across and area (sweep it) to get a measurement.

Revision History:

1999-11-03: Example created.
2000-07-03: Fixed some problems in the code (invalid comments) to compile under IC.