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Prof. Sari Kulthm.MICROPROCESSORS – CET2123C

Lecture 2 – HCS History and Features

Compare and contrast microprocessors and microcontrollers.

Describe the advantages of microcontrollers for some applications.

Explain the concept of embedded systems.Discuss criteria for considering a

microcontroller.Explain the variations of speed, packaging,

memory.Understand cost per unit and how these affect

choosing a microcontroller.

OBJECTIVESthis chapter enables the student to:

Explain the evolution of 68xx microcontrollers.Compare and contrast the various members

of the HCS12 family.Give the history and features of HCS12/9S12

microcontrollers.

OBJECTIVESthis chapter enables the student to:

(cont)

By microprocessor we mean the general-purpose microprocessors such as Intel’s x86 family. 8086, 80286, 80386, 80486, Pentium or Motorola’s PowerPC family

These microprocessors contain no RAM, no ROM, and no I/O ports on the chip itself.

For this reason, they are commonly referred to as general-purpose microprocessors. see fig 1-1

1.1 Microcontrollers and Embedded Processors - descriptions/differences

A microcontroller has a CPU, a fixed amount of RAM & ROM, I/O ports & timer all on a single chip.

1.1 Microcontrollers and Embedded Processors - descriptions/differences

Figure 1-1 Microprocessor System Contrasted with Microcontroller System

• The design makes them ideal for applications in which cost and space are critical.

An embedded product is controlled by its own internal microprocessor (or microcontroller) as opposed to an external controller. typically the microcontroller’s ROM is burned with a

purpose for specific functions needed for the system

A printer is an embedded system because the processor inside performs one task only. namely, getting the data and printing it

Contrast this with any x86 IBM-compatible PC, which can be used for any number of applications.

1.1 Microcontrollers and Embedded Processors - embedded systems

Table 1-1 lists some embedded products.

1.1 Microcontrollers and Embedded Processors - embedded systems

Sometimes a microcontroller is inadequate for the task.

Manufacturers such as Intel, Freescale Semiconductor, and AMD have targeted their microprocessor for the high end of the embedded market.

These processors are often called high-end embedded processors.

Very often the terms embedded processor and microcontroller are used interchangeably.

1.1 Microcontrollers and Embedded Processors - embedded applications

A critical need of an embedded system is to decrease power consumption and space. trend is to integrate more & more functions on the

CPU and let designers decide which features to use

Many companies have a chip that contains the entire CPU and all the supporting logic and memory, except for DRAM. the entire computer on a single chip

Due to Linux, MS-DOS & Windows standardization, many embedded systems use x86 PCs.

1.1 Microcontrollers and Embedded Processors - embedded applications

There are five major 8-bit microcontrollers. Freescale Semiconductor (formerly Motorola)

68HC08/68HC11/12Intel 8051Atmel AVRZilog Z8PIC from Microchip Technology. Each has a unique instruction set and register

set. therefore, they are not compatible with each other

1.1 Microcontrollers and Embedded Processors - choosing microcontrollers

Three criteria for choosing microcontrollers:Meeting the computing needs of the task at

hand. efficiently and cost effectively

8-, 16-, 32-bit? Other considerations… highest speed the microcontroller supports? chip packaging; power consumption amount of RAM and ROM on the chip number of I/O pins and the timer on the chip ease of upgrade to higher-performance versions cost per unit

1.1 Microcontrollers and Embedded Processors - criteria for choosing

Availability of software/hardware development tools. assembler, debugger, a code-efficient C language

compiler, emulator, tools, technical support, andboth in-house and outside expertise

Third-party vendor support for a chip can be as good as, if not better than, support from the chip manufacturer.

1.1 Microcontrollers and Embedded Processors - criteria for choosing

For some designers, ready availability in needed quantities both now and in the future is even more important than the first two criteria.

The 8051 family has the largest number of diversified (multiple source) suppliers. over fifty companies currently produce the 8051

Freescale, Atmel, Zilog, and Microchip Technology have all dedicated massive resources to ensure their products are stable, mature, and single sourced.

1.1 Microcontrollers and Embedded Processors - criteria for choosing

The microcontroller is playing a major role in an emerging field called mechatronics.

Mechatronic systems involves finding an optimal balance between the basic mechanical structure, sensor and actuator implementation, automatic digital information processing and overall control.

Requires multi disciplinary expertise across a range of disciplines, such as: mechanical engineering, electronics, information technology, and decision making theories.

1.1 Microcontrollers and Embedded Processors - mechatronics

In 1974, Motorola introduced the 8-bit 6800 microprocessor. 3 years after Intel had introduced the 4004

In the 80s, the Intel 8085 and 68xx from Motorola dominated the 8-bit microprocessor market. eventually both companies introduced microcontrollers

Intel used a whole new architecture called 8051. not based on 8085

1.2 Overview of the CPU12 and CPU08brief history of the 68xx microprocessor

80’s microcontrollers had small amounts of RAM,a few Kbytes of ROM for the program, a couple of timers, and many pins for I/O ports. on a single 40-pin chip

1.2 Overview of the CPU12 and CPU08brief history of the 68xx microprocessor

Figure 1-2 Simplified View of a Microcontroller

• This changed inthe 90s with PIC microcontrollersfrom Microchip.

To increase performance of 68HC11, Motorola introduced the 16-bit 68HC12 in 1996. the term CPU12 refers to the 16-bit architecture of the

68HC12

CPU12 instructions are a superset of the 68HC11 instruction set code written for 68HC11 can be run on a CPU12

For those who have mastered one family, understanding the other family is easy. since the CPU08 is a subset of the CPU12

1.2 Overview of the CPU12 and CPU08brief history of the 68xx microprocessor

In 2004, the semiconductor division of Motorola became a separate and independent entity called Freescale Semiconductor. put massive efforts and resources into revamping the

microcontroller products

The goal is “easy migration between Freescale's8-bit family and 32-bit ColdFire devices.

Designers can develop new applications using the same software and hardware development toolsfor both 8-bit and 32-bit MCUs.

1.2 Overview of the CPU12 and CPU08Motorola to Freescale

HCS and RS chips - advances in chip design ledto more power-efficient CMOS technology. HC (high-density CMOS) in the Freescale products

The HCS08/HCS12 and RS08/S12 series increase performance and the features of microcontrollers while keeping the power consumption low.

The HCS08/HCS12 and RS08/S12 series have been the answers to these challenges.

See the Freescale website for more information. http://www.freescale.com

1.2 Overview of the CPU12 and CPU08

CPU08 and CPU12 features - on-chip program (code) ROM, data RAM, timers, ADC, and USART (Universal Synchronous Asynchronous Receiver Transmitter) and I/O ports. all have peripherals such as timers, ADC (analog-to-

digital converter), and USART

Microcontroller program ROM type - program ROM size can vary from a few kilobytes to several megabytes, depending on the family member. available in Flash, OTP, and masked

1.2 Overview of the CPU12 and CPU08

Microcontroller with UV-EPROM - some of the microcontrollers used UV-EPROM for on-chip program ROM. requires a PROM burner and a UV-EPROM eraser

Microcontrollers with Flash - is ideal for fast development and used in place of the UV-EPROM. a separate eraser is not needed

OTP version of the microcontroller - one-time-programmable versions of the microcontroller are also available from manufacturers.

1.2 Overview of the CPU12 and CPU08

Masked version of microcontroller - send in your program, a chipmaker will burn the program into the chip during the fabrication process of the chip. cheapest of all types, if unit numbers are high enough there is a minimum order for the masked version

of the microcontrollers

Microcontroller peripherals - ADC (analog-to-digital converter), timers, and USART are standard peripherals. including the CPU08 and CPU12 family members

1.2 Overview of the CPU12 and CPU08

1.2 Overview of the CPU12 and CPU08Freescale chip identification

Figure 1-6 Freescale Chip Identification Scheme

Microcontroller data RAM and EEPROM - RAM space from a few hundred bytes to several kilobytes. EEPROM is optional, mainly for storage of critical data

Microcontroller I/O pins - 8 to 100 pins dedicated for I/O. depends on number of pins in the package, varies widely

BDM (background debug mode) - allows us to examine contents of the CPU such as RAM, ROM, and registers as we trace and debug the program.

1.2 Overview of the CPU12 and CPU08

Other microcontrollers - include the 8051, PIC18, AVR, and Z8.

1.2 Overview of the CPU12 and CPU08other companies and controllers

• AVR is made by Atmel Corp.• Microchip makes the PIC18F/PIC16F.• Zilog produces the Z8 microcontroller.

END ;Chapter One

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The HCS12/9S12 Microcontroller:History and Features