Department of ECE, SSCET: December 2014

EMBEDDED BASIC: CONCEPT

An embedded system is a computer or processor based system that has been designed for a specific purpose.

The system gains its name from the fact that the software is embedded into it for a particular application. The embedded system is not like a PC or other computer that can run a variety of programmes and fulfil a whole host of tasks.

The item using an embedded system is designed for a specific task and has its software preloaded, although updates may be undertaken from time to time.

Embedded systems basics

It may be asked what is an embedded system. With many processor based systems and computers it is useful to define what an embedded system is. A convenient definition for an embedded system is: An embedded system is any computer system contained within a product that is not described as a computer.

Using this embedded system definition it is possible to understand the various basic characteristics one. Typically they are:

GSM Module

GSM/GPRS module is used to establish communication between a computer and a GSM-GPRS system. Global System for Mobile communication (GSM) is an architecture used for mobile communication in most of the countries. Global Packet Radio Service (GPRS) is an extension of GSM that enables higher data transmission rate. GSM/GPRS module consists of a GSM/GPRS modem assembled together with power supply circuit and communication interfaces (like RS-232, USB, etc) for computer. The MODEM is the soul of such modules.

GPS Module

Global Positioning System was developed by the United States' Department of Defense. It uses between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals. This enables GPS receivers to determine their current location, time and velocity. The GPS satellites are maintained by the United States Air Force.

GPS is often used by civilians as a navigation system. On the ground, any GPS receiver contains a computer that "triangulates" its own position by getting bearings from at least three satellites. The result is provided in the form of a geographic position - longitude and latitude - to, for most receivers, within an accuracy of 10 to 100 meters. Software applications can then use those coordinates to provide driving or walking instructions.

Getting a lock on by the GPS receivers on the ground usually takes some time especially where the receiver is in a moving vehicle or in dense urban areas. The initial time needed for a GPS lock is usually dependent on how the GPS receiver starts. There are three types of start - hot, warm and cold.

Capacitor

Why Are Capacitors Important?

The capacitor is a widely used electrical component. It has several features that make it useful and important:

A capacitor can store energy, so capacitors are often found in power supplies.
A capacitor has a voltage that is proportional to the charge (the integral of the current) that is stored in the capacitor, so a capacitor can be used to perform interesting computations in op-amp circuits, for example.
Circuits with capacitors exhibit frequency-dependent behavior so that circuits that amplify certain frequencies selectively can be built.

What Is A Capacitor?

PCB Design

WHAT IS PCB?

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate.

Types of PCB

· Single sided

· Double sided (PTH) Printed Through Hole

· Multi Layer.

DETAIL ABOUT THE PCB:

Tracks

There is no recommended standard for track sizes. What size track you use will depend upon (in order of important) the electrical requirements of the design, the routing space and clearance you have available, and your own personal preference. Every design will have a different set of electrical requirements which can vary between tracks on the board. All but basic non-critical designs will require a mixture of track sizes. As a general rule though, the bigger the track width, the better. Bigger tracks have lower DC resistance, lower inductance, can be easier and cheaper for the manufacturer to etch, and are easier to inspect and rework.

Micro Controller

Microcontrollers give you a fantastic way of creating projects. A PIC microcontroller is a processor with built in memory and RAM and you can use it to control your projects (or build projects around it). So it saves you building a circuit that has separate external RAM, ROM and peripheral chips.

What this really means for you is that you have a very powerful device that has many useful built in modules e.g.

EEPROM.
Timers.
Analogue comparators.
UART.

Even with just these four modules (note these are just example modules - there are more) you can make up many projects e.g.:

Sensor Types

OXYEGEN SENSOR:

An oxygen sensor (or lambda sensor) is an electronic device that measures the proportion of oxygen (O₂) in the gas or liquid being analysed.The most common application is to measure the exhaust gas concentration of oxygen for internal combustion engines in automobiles and other vehicles. Divers also use a similar device to measure the partial pressure of oxygen in their breathing gas.

IR DISTANCE SENSOR:
This SHARP distance sensor bounces IR off objects to determine how far away they are. It returns an analog voltage that can be used to determine how close the nearest object is. Comes with 12" long 3-JST interface wire. These sensors are good for short-range detection. For over 1 m distance, we suggest using sonar sensors

To use, connect black wire to ground, red wire to 5V and white wire to analog input. The analog voltage out will range from 3V when an object is only 4" (10 cm) away and 0.4V when the object is 32" (80 cm) away

PIR SENSOR:

PIR sensors allow you to sense motion, almost always used to detect whether a human has moved in or out of the sensors range. They are small, inexpensive, low-power, easy to use and don't wear out. For that reason they are commonly found in appliances and gadgets used in homes or businesses. They are often referred to as PIR, "Passive Infrared", "Pyroelectric", or "IR motion" sensors.

MORE DETAIL.

ALCOHOL SENSOR:

Alcohol Gas Sensor - MQ-3

SEN-08880

Description: This alcohol sensor is suitable for detecting alcohol concentration on your breath, just like your common breathalyzer. It has a high sensitivity and fast response time. Sensor provides an analog resistive output based on alcohol concentration. The drive circuit is very simple, all it needs is one resistor. A simple interface could be a 0-3.3V ADC.

Features:

5V DC or AC circuit
Requires heater voltage
Operation Temperature: -10 to 70 degrees C
Heater consumption: less than 750mW

Dimensions:

16.8mm diameter
9.3 mm height without the pins

TEMPERATURE SENSOR:

Description: This is the same temperature sensor that is included in our SparkFun Inventor’s Kit. The TMP36 is a low voltage, precision centigrade temperature sensor. It provides a voltage output that is linearly proportional to the Celsius temperature. It also doesn’t require any external calibration to provide typical accuracies of ±1°C at +25°C and ±2°C over the −40°C to +125°C temperature range. We like it because it’s so easy to use: Just give the device a ground and 2.7 to 5.5 VDC and read the voltage on the Vout pin. The output voltage can be converted to temperature easily using the scale factor of 10 mV/°C.