Applications of an Embedded System

To understand the various applications of embedded systems, the applications are divided into the following market segments, each of which is covered in the following sections:

·         Consumer electronics

·         Control system and industrial automation

·         Biomedical systems

·         Field instrumentation

·         Handheld computers

·         Data communication

·         Telecommunication

·         Wireless

Consumer Electronics

Consumer electronics items such as toy, air conditions, refrigerators, microwave ovens, CD player, MP3 players, television sets, Web-enabled TV sets, and so on are embedded systems with varying processing power and memory requirements. However, each of these systems must be highly reliable and of low cost. Another important feature of these items is that each uses different processors; therefore, different software needs to be written for each type of item by each manufacturer. This was once a major problem, but in recent years, with the advent of Java, things are changing. The write once run anywhere slogan of Sun Microsystems will be applicable to these appliances once Java’s use becomes prevalent for embedded software development in the future. However, note that most reliable and efficient extant embedded systems existing as of now are not built using Java technologies.

Control systems and industrial automation

Using embedded systems in industrial control and automation has been pervasive ever since microprocessors came into vogue.

·         The embedded system takes electrical signal as input. Generally, sensors or transducers are used to convert the physical entity into an electrical signal. For instance, thermostat Integrated Circuit (IC) is used to sense the temperature and convert it into an electrical signal, the amplitude of the signal being proportional to the temperature. In applications such as those using voice or video, a transducer converts the voice or video signal into an equivalent electrical signal. An embedded security system that transmits video uses a video camera, which is the transducer that converts the image into an equivalent analog video signal.

·         However, because the processor can process only digital signals, the ADC (Analog-to-Digital Converter) converts the analog signal into its equivalent digital signals, which is an electrical representation of a bit stream of 1s and 0s.

·         The processor processes these signals using the software that resides on the memory chip (Read-Only Memory).

·         RAM is used to store the volatile data. If the embedded system has to control another system or if it has to directly control another appliance, a DAC (Digital-to-Analog Converter) is used to convert the output digital signal to analog format.

·         The processor board also includes input/output interfaces such as a serial interface, a USB port, and an Ethernet port for connectivity to external systems. For user interaction, LCD (Liquid Crystal Display), LEDs (Light Emitting Diodes), and a keypad are provided.

·         The LCD size can also vary – some applications may require only a 2 x 8 display (2 lines with 8 characters on each line), whereas other applications may demand a 6.4 inch display.

·         To display status information, LEDs of different colors may be used, such as red, green, and so on.

Choice of components plays an important role for such systems. Most components work well in the temperature range of 0-50 degree Celsius. If the system has to operate at lower temperatures, military-grade components need to be chosen. If an LCD display is to be used, note that it will work beyond -5 degree Celsius, as the liquid in the LCD becomes solid.

Biomedical systems

Much of the progress made in the health-care industry is due to development in the electronics industry. Hospitals are full of embedded systems, including X-ray control units, EEG and ECG units, and other equipment used for diagnostic testing, such as colonoscopy and endoscopy.

Biometric systems for fingerprint and face recognition are gaining wide use in agencies concerned with security. As you might guess, these are complex systems with high memory requirements. The input fingerprint must be processed and compared with the available database using pattern-recognition algorithms, which require intensive processing. The biometric systems use a Digital Signal Processor (DSP) for signal processing, such as filtering and edge enhancement of the image; and a general-purpose processor for implementing pattern-matching algorithms.

Field Instrumentation

Testing and measuring instruments represent some of the oldest embedded systems. Instruments that measure parameters such as temperature, humidity, voltage, current, power, frequency, spectrum, and other signal characteristics need to perform a lot of processing. Response time is not important for some instruments, whereas for others it is a critical factor. Instruments that monitor real-time signals must display their output with very little delay.

Handheld computers

Handheld computers are becoming increasingly powerful. The original Personal Digital Assistants (PDAs) were used mainly to store data. Now, with low-cost 32-bit processors, the computing power on the handheld has increased multifold. Such a device runs a powerful operating system such as Windows CE, Palm OS, Symbian OS, and so on; and provides applications for numerous service, including e-mail, a calendar and an address book.

In addition to computing power, it offers a lot of communication power as well. Using interfaces such as USB, IrDA (Infra-red Data Association’s standards-based communication using Infrared links), the RS 232 serial communication interface, or Ethernet, it can connect to the desktop PC or communicate through a built-in modem directly to the Internet Service Provider. The handheld computer can receive input via full-fledged keyboard or via a form of handwriting recognition, such as used in Palm OS.

The memory, dynamic RAM and flash memory, capacities are also very high, although still not approaching as much as we have on desktops. To provide audio and video capability to the handheld computer, peripherals such as microphone a speaker and a video camera are provided.

Data communication

The Internet has acted as the catalyst for embedded systems. The modem that connects two computers – yours with one owned by your ISP – is an embedded system. With users demanding ever-increasing speeds to access the Internet, advanced modems providing speeds up to 8 Mbps are now becoming available.

Telecommunications

Telecommunications infrastructure elements include networking components such as telephone switches, loop carriers, ISDN network terminators, terminal adapters, ATM switches, frame relays and paging base stations. Mobile communications components encompasses base stations, mobile switching centers, and satellite communication equipment such as earth station controllers, onboard processing elements, telemetry and telecommand systems, and cable TV infrastructure network elements. Some representative embedded systems for telecommunications are listed:

·         Audio codecs

·         Interactive Voice Response (IVR)

·         Video codecs

·         Global Positioning System (GPS) receivers

Wireless communication

Wireless communications has been in use since the 1960s, but only since the last decade of the twentieth century has there been tremendous progress in digital wireless networks. The 2G (second-generation) wireless networks are capable of supporting voice services and data services up to 14.4 kbps. With the advent of 2.5G and 3G wireless network, data rates in the range 64 kbps to 2 Mbps are supported, paving the way for multimedia communication over the wireless networks.