5.4 Microcontrollers I:

Introduction

Dr. Tarek A. TutunjiMechatronics Engineering Department

Philadelphia University, Jordan

Microcontrollers: Introduction

Microprocessors were described in the last three sequences

In this presentation

• Microcontrollers will be introduced

• PIC microcontroller architecture will be highlighted

What is a microcontroller ?

A microcontroller (MCU) is a computer-on-a-chip IC fabricated using VLSI technology and used to control electronic devices.

Microcontrollers contain the following components:• Microprocessor - ranging from simple 8-bit to

sophisticated 64-bit processors

• Input/Output interface ports

• Timers and Interrupts

• RAM for data storage

• ROM, EEPROM or Flash memory for program storage

• Many include A/D converters and serial ports

Therefore, mcontrollers do not require much hardware support (compared to mprocessors) and are used for specific control applications

Microprocessor

I/OPorts

MemoryRAM / ROM

TimerInterrupts

Microcontroller as a computer

Microcontroller can provide all the main elements of a computer

For example, we can use 7-segment display (instead of a monitor) and keypad (instead of a keyboard) with a microcontroller to do simple word processing

MPU

1 2 34 5 67 8 9* 0 #

Clock

7-segment display

4x3Keypad

mcontroller

Select Control Select Control

Read Keys

Write character

Selection of Available

Microcontrollers Intel

• 8051 (8-bits)

• 8096 (16-bits)

• 80960 (32-bits)

Microchip • PIC 16Fxxx (8-bits)

Texas Instruments • TMS370

Motorola • 68HC11 (8-bits)

• 68HC16 (16-bits)

• MPC500 (32-bits)

Selecting a microcontroller

Different microcontrollers provide different combinations of features. The following features should be considered when choosing a microcontroller for your application:• Number of I/O pins• Type of Timers• Interrupt sources• Analog inputs• Maximum clock speed• Program memory size• Data bit size• Serial communication• Simulator• Emulator• Programmer• Price

Motorola 68HC11 Architecture

PIC microcontroller families 12Fxxx

8-pin package 6 I/O pins1 K word program memory 20 MHz clock8- and 16-bit timer Up to 4 analog inputs (10 bits)

16Fxxx14-40 pin packages 12-33 I/O pins1-8 K word program memory 20 MHz clock2x8- and 2x16-bit timers Up to 8 analog inputs (10 bits)Serial communication port 1/2 PWM output & compare in

18Fxxx18-80 pin package 13-68 I/O pins2-64 K word program memory 40 MHz clock2x8- and 3x16-bit timers Up to 16 analog inputs (10 bits)Serial communication port Up to 14 PWM out & compare in

Common Features of

PIC Architecture Harvard architecture

• Separate paths for the instructions and data

RISC instruction set• Small number of instructions

Flash program ROM• Easily re-programmed

Single Working register• Reduces the cumber of complexity of instructions

Multiple Interrupt sources• Variety of interrupts are available at one address

Hardware timers• 8- and 16-bit timers are available

Sleep mode• Power saving

Serial in-circuit programming• Common program downloading system

PIC Architecture

Programming Steps

Write Algorithm

Edit source code

Assemble program

Simulate code

Download code

Emulate in H/W

Stop

Start

Syntax error

Logical error

Functional error

Yes

Yes

Yes

PIC Development Board

After the PIC program is assembled and simulated, the hex code is downloaded on the PIC chip. This is done through serial (or parallel) connection between the computer and the development board

During the download, 14 Volts are applied to MCLR, the clock to RB6 and data to RB7

Summary

A microcontroller is a computer-on-a-chip IC fabricated using VLSI technology and used to control electronic devices

Microcontrollers contain microprocessors, memory, and I/O ports

When choosing which microcontroller to use, the following are to be considered: number of I/O pins, timers, interrupt sources, analog inputs, maximum clock speed, program memory size, and price

PIC microcontrollers made by Arizona microchip are very popular because of their special architecture that results in effective controllers with easy-to-use programs

Programming microcontrollers include assembling, simulating and emulating