(Dr. B. Ram, Patna, India)

When a single IC contains all essential components of a microcomputer, it is called single-chip microcomputer. Single – chip microcomputers are mostly used for dedicated applications such as industrial control, instrumentation and control of computer peripherals. Some examples of computer peripherals. Which are controlled by single-chip microcomputers are: keyboard, printer, MFDs (Multifunction Devices), As a single-chip microcomputer is embedded in the system which it controls, it is called embedded processors are also designed microcomputers are generally used for control applications, they are also called microcontrollers.

There are two distinct areas of embedded control application; event control (real-time) and data control. The controllers needed for real-time control, are usually dedicated to single function applications which includes the control of a motor, an engine, an indicator, temperature control of a furnace etc. Data control application includes data processing, data formatting, I/O control etc. The controllers or processors which are used for data control application must perform many different functions while handling large programs using large amount of data. Examples of high-and data control are: image processing, graphics, networking sophisticated industrial control etc.

A single microcomputer contains a CPU, RAM, ROM or EPROM or Flash Memory; I/O lines, programmable timer/counter, etc. Some single-chip microcomputers also contain A/D converter, D/A convert, DMA controller, serial port, pulse-width modulator, etc. In case of a signal-chip microcomputer, programs are fixed and need not be changed s they are used for dedicated applications. They are stored in a ROM, PROM, EPROM or Flash Memory. Therefore, these memories are called program memory. The data are held in RAM and hence, it is called data memory.

Intel Corporation introduced 8048 series of 8-bit single-chip microcomputers in the year 1976. This series is also known as MCS-48. Its family members are: 8048, 8748, 8050AH, 8748AH, 8741, 8039AH etc. The 8048 series of micro controllers were the first – generation of micro controllers. They were widely used in instrumentation etc. It had only add arithmetic instructions, no multiplication and division instructions.

In the year 1980, Intel introduced 8051 (MCs-51) series of micro controllers. These micro controllers were the second-generation of 8-bit micro controllers. Theses micro controllers are sill popular and widely used for industrial control, instrumentation, appliances control etc. The have enhanced instruction set including instructions for multiplication and division, large memory capacity full duplex serial port, Boolean processor and power saving modes of operation. In power-seving mode, the components which are not in use are switched off. Some versions have functions like A/D converter, D/A converter, DMA channels, pulse-width modulator, watch dog timer etc.

The function of a watch dog timer is to reset the system if the software does not operate properly. The family members of 8051 are: 80c51, 87c52, 87c52, 87c54, 87c58, 83c51 etc. Its different versions are designed for different types of applications. Memory capacity, operating frequency hardware supports etc. differ from version to version but all versions have same instruction set and architecture. Different application set and architecture, different applications require different memory capacity, different hardware and so on. Keeping all these factors in mind deferent versions of a microcomputer family are designed.

In the year 1983, Intel Introduced 16-bit micro controllers, 8096 series. This series is more powerful than 8051 series. Its family members are: 8096, 8798, 80196, 80396, and 80796 etc.

Intel also developed more powerful 8-bit micro-controllers MCS-151 and MCS-251 series. The MCS-251 series was introduced in the ear 1995. It gives 5 times increased performance as compared to MCS-51.

Microcontrollers are also manufactured by many other companies: - Motorola, IBM, National semiconductors, Texas Instruments, NEC, Hitachi etc. 8-bit microcontroller of Motorola is MC68 HC11; its 32-bit microcontrollers are MPC 505 and 68300. Microcontroller of IBM is 403GA. 32-bit microcontrollers are used for sophisticated applications.

4-bit microcontrollers have also been developed. They are used for appliances and toys. Some examples of 4-bit microcontrollers are Texas Instruments TMS 1000, Hitachi’s HMCS40, National’s COP420, OKI’S MSM6411, and Toshiba’s TLC47 etc.

Embedded Processors

Embedded processors are used for data control applications where large amount of data is to be processed, for example, image processing, laser printing graphics, networking, and sophisticated industrial control etc. Designers select embedded processor and add supporting chips, I/O, memory required for a particular application and develop a suitable embedded controller for it.

Intel developed 8090 series of 32-bit embedded processors for complex industrial control applications. Its family members are 80960SA, 80960SB, 80960KA, 80960KB, 80960CA etc. The 80960CA the second generation member of 80960 family. This superscalar embedded processor. The 80960KB contains a built-in floating-point unit. Its applications included machine control, robotics, process control, avionics, wide-area telecommunication, etc.

Motorola has developed 68060, a 32-bitembedded processor. It is a 32-bit CLSC processor where as its MPC 505 a microcontroller is RISC microcontroller. IBM’s 403GA is also a RISC microcontroller. Motorola has also developed a series of processor components and small computers configurations, called Cold Fire Family for embedded applications. These are based on 68060 processor core. Motorola’s Power PCs also used for embedded applications.

National semiconductors has developed Geode SC1400, chip for embedded applications. Processors of ARM and MIPS are also used in embedded applications.

Programs for embedded system for a particular application are developed in a laboratory using a large powerful computer. The codes of the program are written into ROM, EPROM or flash memory the microcontroller/embedded systems. Interfacing for the application is developed and tested in the laboratory. Then an embedded controller or an embedded is developed and tested in the laboratory. Then an embedded controller or an embedded based system is used in industry is used in industry, instrument, in process control etc.

Contributor: Prof. B. Ram is in NIT, Patna. He wrote many books on microprocessor and Micro controller. This article is on compiled from of his inaugural Center, at workshop on Embedded System on Feb 06, 2006 at Dept of Physics Patna Science College, Patna.

 

View Index

FeedBack