INTRODUCTION TO THE MICROPROCESSOR AND DEVELOPMENT OF MICROCONTROLLERS

Transcription

1 INTRODUCTION TO THE MICROPROCESSOR AND DEVELOPMENT OF MICROCONTROLLERS ABSTRACT This chapter provides a brief review on the evolution of microprocessors (pps) and development of microcontrollers (pcs). The use of microcontrollers in embedded systems and their applications are explained briefly.

2 2 1.1 EVOLUTION OF THE MICROPROCESSOR Intel Corporation, USA introduced the first pp, the 4004, in This 4004 has evolved from a development effort while designing a calculator chip set. Soon after the 4004 appeared in the commercial market, three other microprocessors were introduced. These were the Rockwell International PPS-4, the Intel 8-bit 8008, and National semiconductor 16-bit IMP 16. The microprocessors introduced between 1971 and 1973 were the first generation systems They were designed using the PMOS technology. This technology provided low cost, low speed, and low output currents and was not compatible with TTL. After 1973, second-generation microprocessors such as Motorola 6800 and 6809, Intel 8085 and Zilog Z80 were evolved. These processors were fabricated using the NMOS technology. The NMOS process offers faster speed and higher density than PMOS and is TTL-compatible. After 1978, the third generation microprocessors were introduced. These processors were 16 bits wide and include typical processors such as Intel 8086/80186/80286 and Motorola 68000/ These microprocessors were designed using the HMOS (high-density performance MOS) technology. Intel utilized the HMOS technology to fabricate the 8085A. Thus, Intel offered a high-speed version of the 8085A called 8085AH. In 1980, fourth generation microprocessors evolved. Intel introduced the first commercial 32-bit microprocessor, the problematic Intel 432. This processor was eventually discontinued by Intel. Since 1985, more 32-bit microprocessors have been introduced. These include Motorola s MC and and Intel Some

3 3 other 32-bit microprocessors are Intel s 80486, Pentium, Pentium pro, Pentium II, Pentium III, Pentium IV etc. These processors were fabricated using the low-power version of the HMOS technology called the HCMOS. The performance offered by the 32-bit microprocessor was more comparable to that of Super Minicomputers such as Digital Equipment Corporation s VAX11/750 and VAX11/780. Motorola has introduced a 32-bit RISC Microprocessor with simplified instruction set called the MC Examples for 64-bit Microprocessors include SUN s ULTRASPARC, Power PC620, MIPS R5000, R10000 and 12000; Intel PA8000 etc. Intel s i860 (1989) was a 64-bit RISC microprocessor, but it did not become popular for general purpose computers. It was used for industrial control applications [1, 2, 3], 1.2 DEVELOPMENT OF SINGLE CHIP MICROCOMPUTER/ MICROCONTROLLER A digital computer built on a single chip (single IC) is called single-chip miciocomputer (or microcontroller). A single-chip microcomputer contains a CPU, RAM, ROM or EPROM, I/O lines, programmable timer/counter. Some single-chip microcomputer also contains Analog to Digital (A/D) converter, DMA channels, serial port, etc. As microcontrollers are embedded in the system which they control, they are called embedded controllers. Intel introduced the 8048 series of single-chip microcomputers in the year The 8048 contained an 8-bit CPU, 1K/2K/4K bytes ROM, 64/128/256 bytes

4 4 RAM, three 8-bit I/O ports, a timer/counter and are interrupt line The summary of 8048 series (MCS-48) of microcontrollers is shown in Table 1.1. Intel introduced the 8051 (MCS-51) series of micro- controllers (1980) which are more powerful than Intel 8048 series. The 8051 series of micro- controllers are the second generation of microcontrollers. They are faster, have enhanced instruction set including instructions for multiplication and division, larger memory capacity, full duplex serial port, Boolean processor and p.ower saving modes of operation. Some selected versions have functions like A/D converter, DMA channels, pulse-width modulator, watch dog timer etc Table 1.2 shows the details of MCS-51 series. Dallas semiconductor (DS) was the first company which has changed the 805 l s microcoded processor core with hardwired one. This change has resulted in instructions taking 4, 8, 12 or 16 clock cycles per instruction. Further, there was an improvement of 2.5 fold in the DSHSM as compared to the basic 805IS. The difficulty in using DSHSM and the normal 8051 can be reduced if one is working with timers having a divisor of 12. Dallas HSM has an additional timer called Timer 2. Timer 2 can work in two modes. Capture mode Auto-reload mode Further, a watch dog timer (WDT) is used to protect an application in case the microcontroller begins to run and execute randomly. Dallas semiconductors HMS s has a second serial port. The second serial port can only be driven by timer 1 overflow.

5 TABLE 1.1 Device ROM/EPROM RAM 8050AH 4 KB ROM 256 bytes 8049AH 2 KB ROM 128 bytes 8048AH 1 KB ROM 64 bytes KB ROM 64 bytes 8040AHL None 256 bytes 8039AHL None 128 bytes 8035AHL None 64 bytes 8749H 2 KB EPROM 128 bytes 8748H 1 KB EPROM 64 bytes KB EPROM 64 bytes

6 TABLE 1.2 s. No. Product Technology On-chip program memory CLK On-chip data memory (Bytes) 1 80C51BH CHMOS 4 KB ROM 24 MHz 128 bytes 2 80C31BH CHMOS None 24 MHz 128 bytes 3 87C51 CHMOS 4KB EPROM 24 MHz 128 bytes 4 8XC52/54/58 CHMOS 8/16/32 KB 12/24/33 MHz 256 bytes 5 8XL52/54/58 CHMOS 8/16/32 KB 20/16 MHz 256 bytes 6 8XC51FA/FB/FC CHMOS 8/16/32 JCB 12/24/33 MHz 256 bytes 7 8XL51FA/FB/FC CHMOS 8/16/32 KB 20/16 MHz 256 bytes 8 8XC51RA/RB/RC CHMOS 8/16/32 KB 24 MHz 512 bytes 9 8XC51GB CHMOS 8KB 3.5 to 12/16 MHz 10 8XC51SL CHMOS 16 KB 2 to 16 MHz 256 bytes 256 bytes 11 8XC152JA/JB/ JC/JD CHMOS 8KB 16.5 MHz 256 bytes

7 5 Intel s MCS 151 and 251 microcontrollers are an enhancement to the original 8051 with number of changes and improvements. ATMEL introduced a series of microcontrollers: AT S9C51/C52/LV51/LV52/C1051/C2051 microcontrollers. They include on-chip flash memory. Microchip introduced a series of microcontrollers: PIC 12C5xx, PIC16C5x, PIC16F84, PIC16F83, PIC16C etc. Table 1 3 shows the other series of microcontrollers (8-bit) designed by different manufacturers, such as Dallas, ATMEL, National and Hitachi series [4], In the present work, Atmel s 89C51 microcontroller is used. 1.3 CONCEPT OF EMBEDDED SYSTEM AND USE OF MICROCONTROLLERS IN EMBEDDED SYSTEMS Embedded means hidden or buried. The embedded information is truly hidden inside the device/product that is in use. This is possible by programming security bit/code in a microcontroller program. In the commonly used appliances such as washing machine, the embedded software adjusts the water level basing on the load and adjusts the washing cycle basing on the dirtiness of the water. The use of simple microprocessors in embedded intelligence has gradually decreased and the use of microcontrollers in such an environment has not only increased but also brought in a revolutionary change. This is indeed due to the integration of microprocessor and certain peripherals (including memory) on a single chip known microcontroller. Thus it can be thought of as gp++. The embedded information processing revolution is happening all around us. Electronics intelligence is hidden inside the products that we use in daily lives. As the

8 TABLE 1.3 Manufacturer: Model Pins: I/O Counters RAM (bytes) ROM (bytes) National: COP820 28: IK Motorola: : IK Motorola: 68HC11 52: K Rockwell: 6500/1 40: K Philips: 87C552 68: K Zilog: Z8 40: K Zilog: Z86C83 28: K TI: Tms : K TI: Tms 370C050 68: K Microchip: PIC 16C56 18/ IK DS K

9 6 cost of ICs that provides this intelligence has dropped over the years, the number of manufacturers using these devices and diverse applications have increased. Competitive pressures require manufacturers to expand their product functionality and provide differentiation while maintaining or reducing the cost. To address these requirements, manufacturers use IC based embedded control systems that provide an integrated solution for applications specific control (ASC) requirements. Embedded control systems enable manufacturers to differentiate their product, replace less efficient electromechanical control devices, add product functionality, and significantly reduce product costs. In addition, embedded control system facilitates the emergence of complete new classes of products. Embedded control system typically incorporate microcontroller for the principle activity, and some times or the sole component. A microcontroller itself contains computer on a chip, which includes CPU, non-volatile program memory, RAM for data storage and various I/O capabilities. In addition to the microcontroller, a complete embedded control system incorporates applications specific software and may include specialized peripheral controllers and external non-volatile memory components, such as E2PROM to store additional program software. Embedded control solutions have been incorporated into thousands of products and sub-assemblies in a wide variety of markets, world-wise. Some of these applications include > Automotive air bag systems

10 7 > Remote control devices > Hand held tools applications > Portable computers > Cordless and cellular telephones > Motor controls > Security systems The increasing demand for embedded control has made the market for microcontrollers as the largest segments of the semiconductor market. Currently available microcontroller architectures range from 4-bit through 32-bit. 1.4 APPLICATIONS OF EMBEDDED MICROCONTROLLERS There are two distinct areas of embedded control applications: event control (real-time control) and data control. The controllers required for real-time control are usually dedicated to single function applications, which include the control of a motor, an engine, an indicator, etc. Data control applications include data processing, data formatting, I/O control, etc. For such applications, the embedded controller is often found in a subsystem which performs multiple functions repeatedly and supports programs that move vast quantities of data. Such applications require a combination of processing power, DMA and I/O bus bandwidth. The controllers which are used in data control applications must perform many different functions while handling large programs using large amounts of data. A typical example of a high-end data control application is the control of a laser printer. Other examples of high-end data control are: image processing, graphics, networking, sophisticated

11 8 industrial control, digital switching networks, medical instrumentations and LAN controllers, etc. The embedded applications include industrial automation, avionics, image processing, graphics, etc [5,6], This type of environment is depicted in Figure 1 1 [7], Some of the other examples for embedded system are: Printer, modem disk controller, sound card CD-ROM driver mouse, Toaster, small ASCII data terminal, Chess player and House thermostat, etc. The above review indicates that the microcontrollers are widely used in different applications, especially in embedded systems. This dissertation is an approach to develop an embedded system to improve the low cost web camera. The proposed system not only replaces the costly web camera used in video conferences, shopping complex etc., but has more functionality compared to the commercially available web cameras.

12 Fig Embedded system in common environments

13 9 REFERENCES 1. Mohamed Rafiq Zzaman, Microprocessors and Microcomputer based system design, USB Pub. (1999). 2. Badri Ram, Advanced Microprocessors and Interfacing, Tata Mc-Graw Hill Publishing Company (2002). 3. Ramesh S. Gaonkar, Microprocessor Architecture, Programming and Applications with the 8Q85/8G80A, Wiley eastern Limited. 4. Kenneth J. Ayala, the 8051 Microcontroller Architecture, Programming of Applications, Penram International Publication (Second Edition). 5. Mohammad Ali Mazidi, Janice Gillispie Mazidi The 8051 Microcontroller and Embedded Systems, Pearson Edu. (2002). 6. MYKE PREDKO Programming and customizing the 8051 Microcontroller, Tata Mc-Graw Hill Publishing Company (2001). 7. Frank Vahid, Tony Givragis Embedded system design. A unified hardware/software introduction, John Wiley and Sons, Inc )