OBJECTIVE We will build a passive infrared motion detector that can detect movement from distances that are between 3m and 7m. THE SCIENCE All objects that have a temperature above absolute zero (0 ° Kelvin/-273.15 ° C/-459.67 ° F) emit heat in the form of infrared radiation. The hotter the object is, the more radiation…
THE PROBLEM It is not possible to directly control a motor with an Arduino because of the low of the signal from the Arduino and because the current consumption of the motor will be too high for the Arduino. THE SOLUTION What is needed is a circuit to interface the motor and Arduino. Such a…
OBJECTIVE A range finder is a device that is used to find the distance between two points, using a technique known as ranging. In this project we will design and build a range finder that can measure how far away an object is, from 2 cm to 4 m (0.79 in to 13.12 ft). The…
OBJECTIVE The objective here is to build an ohmmeter, which is a device for measuring resistance. The approach that we will use is to make a voltage divider circuit. This will consist of two different resistances. One will be fixed and the other will be the one which we wish to test. Because the two…
OBJECTIVE For this project we will build a single traffic light that follows the correct sequence (in the UK) of RED, RED and AMBER, GREEN, AMBER, RED. THE HARDWARE We will need a red, orange (or yellow) and green LED; 3 220Ω resistors and your Arduino. THE CIRCUIT THE CODE The first thing that we…
THE PROBLEM Switch bounce can be problematic in some circuits if no action is taken to address it. We live in an analogue world but often want to provide a digital input to circuits, switch bounce is one of the issues that arise from this. Essentially the job of a switch is to transition between…
INTRODUCTION Interrupts are very important processes that occur in many circuits. Many circuits have a process that monitors what is going on and if the correct parameter(s) are met then an interrupt will kick in – it interrupts what was happening! We can split interrupts into hardware and software. Hardware interrupts These occur when an…
Serial Peripheral Interface (SPI) is a data protocol that is used by microcontrollers for communicating with one or move peripheral devices, quickly and over short distances. SPI can also be used to communicate between two microcontrollers but whatever the situation, there is always one device that is designated as the master device. It is the…
The inter-integrated (I²C) protocol allows communication between devices, with some designated as master devices and others as slave devices. As with SPI, it is designed for communication over short distances. However, unlike SPI, it is asynchronous. This means that only two wires are needed to exchange data. A further advantage is that it supports a…
It is very important that the correct resistor value is chosen for your LED. The correct value is dependent on four factors: Supply voltage Current flowing through the LED LED forward voltage (dependent on colour) To calculate resistance we use Ohm’s law. This states that the current through a conductor is directly proportional to the…