Fundamental of Microcontrollers

Waghmare Rahul G.

Purpose◦ Provides an introduction to microcontrollers including

usage and selection Objectives:

◦ Describes the functions of a microcontroller◦ Briefly explains the history of microcontrollers◦ Describes the main components of microcontroller◦ Talk about trends seen in the microcontroller industry◦ Describe the current microcontroller offerings◦ Describe the some of the steps in first using a

microcontroller◦ Show usage of an Evaluation kit◦ Provide insight into how to choose a microcontroller for

your application

Introduction

Microcontroller◦ Single chip device◦ System decision based on external

signals◦ Controls the behavior of a system

Always Contains:◦ Processor Core◦ Memory (RAM, ROM)◦ Input/output (I/O) Capability

Serial I/O interface◦ Various On-Chip Peripherals such as:

Timers Analog to digital converters Pulse width Modulators Many others

What is Microcontroller

MemoryI/O Peri

perals

Processor Core (CPU)

Everywhere◦ Any application that has real world inputs and

outputs Examples:

◦ Washing Machine◦ ECG Machine◦ Networking equipments◦ PCOs◦ etc..

Where are Microcontrollers?

What is difference between a Microcontroller and a Microprocessor?

CPU core with memory and peripherals integrated on chip

CPU core connects to external memory and peripherals

What is difference between a Microcontroller and a DSP?

History of the Microcontrollers

History of the Microcontroller:Early Time

General Instruments:◦ The famous PIC◦ Spun out chip Division - Microchip

Hitachi◦ 6300 line◦ Combined with Mitshibushi Electric to form

Renesas Zilog

◦ First the Z – 80 processor, then Z – 8 MCU

History of the Microcontroller:Other Early Entries

Architecture

CPU◦ Reads and Stores

data◦ Performs Basic Math

Operations◦ Performs Logical

functions (OR, AND etc)

◦ Controls flow of program execution

Processor Core

Microcontroller bit definition

CISC V/S RISC

Complex Instruction Set Computer

Reduced Instruction Set Computer

Harvard V/S von Neumann

Hardware to handle interrupt signals Important in real time system Interrupt latency in important to consider

◦ Hardware and software (OS) determine interrupt latency

◦ Interrupt service routine (ISR) is the part of OS

Interrupt controller

ROM – Read-only Memory – for program storage◦ Masked ROM

Programmed during manufacture◦ PROM

Programmed by blowing fuse after manufacture◦ EPROM – Erasable ROM

Electrically programmed – Erased by UV light◦ OTP – One Time Programmable

PROM EPROM that is encapsulated

◦ EEPROM – Electrically Erasable ROM Electrically programmed – Erased with higher voltages

◦ FLASH Similar to EEPROM Write/Read/Erase in large blocks

System Memory: ROM

RAM – Random Access Memory◦ Volatile or Non-permanent memory◦ Can be written to many times◦ Stores Temporary or changeable data◦ “Embedded” in MCUs

Types of RAM◦ SRAM

Static RAM Fast Access times / More Silicon area Common in MCUs

◦ DRAM Dynamic RAM Slower access time / Lesser Silicon area Less common in MCUs

System Memory: RAM

Allow Communication with other devices◦ USB (Universal Serial Bus)◦ CAN (Controller Area Network)◦ SPI (Serial Peripheral Interface)◦ I2C (Inter Integrated Circuit)◦ UART (Universal Asynchronous

Receiver/Transmitter)◦ LIN (Local Interconnect Network)◦ Ethernet◦ Also Wireless Interfaces

ZigBee Bluetooth

I/O: Serial Interface

Timers LCD Controllers Touch screen

Controllers Keypad Controllers GPIO pins A/D Converter D/A Converter Analog Comparator Pulse Width Modulator

On chip Peripherals

Trends andCurrent Offerings

Low Power◦ Dynamic Power◦ Static Power◦ Low Power Modes◦ Lower Supply Voltage

Higher Integration◦ More Feature Incorporated

Microcontroller Trends

32 bits◦ More Processing power

Flash Memory◦ May replace the traditional ROM

DSP Functionality◦ DSP or Microcontroller

Multi-core◦ Not just for PCs

Microcontroller Trends

8051◦ NXP, Atmel, Silicon Labs, Dallas/Maxim, ST,

Rabbit and others ARM

◦ NXP, ST, Free-scale, Atmel, Samsung, Texas Instruments, OKI, Energy Micro and others

MIPS◦ Microchips

Sampling of Microcontroller offerings:Licensed cores

NXP Renesas Microchip Free scale Atmel Infineon

Texas Instruments Samsung & ST

Microelectronics NEC Toshiba

Sampling of Microcontroller offerings:Broad range Vendors

Analog Devices Cyan Maxim / Dallas Zilog Silicon Labs Cypress Energy Micro Rabbit

Sampling of Microcontroller offerings:Broad range Vendors (more..)

Designing with Microcontrollers

Editor◦ Text based window for editing high-level language

Compiler◦ Converts source code to object code

Assembler◦ Converts assembly code to binary code

Linker◦ Joins separate object code files for download

Simulator◦ Run linker output on a simulation of the MCU on host PC

Debugger◦ Allows engineer to monitor and halt program execution

Microcontroller Development Tools

Integrated Development Environment (IDE)◦ Software package that contains all software tools integrated

In-Circuit Emulator◦ Replaces MCU with tool to allow viewing and control of

program as seen within the chip JTAG

◦ Interface for test and debug Evaluation / Development Kits

◦ Low cost Easy-to-use Evaluation and development tool 3rd Party tools

◦ Various tools by Non-MCU vendor that help in all aspects of development including development including kits and JTAG Debugging

Microcontroller Development Tools

A software platform which manages task created by user◦ Design team may write their own OS

Drivers handle details of using I/O and peripherals◦ Makes programming easier; just call on drivers for I/O◦ Makes program reusable; MCU hidden from designer◦ Drivers control peripherals; simply pass data to them

Real time Operating System (RTOS)◦ Designed to execute multiple tasks with definite time

constraints and priorities

Operating System

Programming code Compiler Memory Highly Integrated Microcontrollers make circuit design

easy but…◦ Must be programmed in order to perform a function◦ Code development is more than half the product development

A program is a sequence of instructions using the microcontroller’s unique instruction set◦ Families of MCUs may have a common instruction set◦ Typical Instruction includes:

Adding two numbers, and saving the result Comparing two numbers and branching to different subroutines if

equal or not equal Reading the value of an external pins

Code Development

Compiler

Evaluation Kit◦ Low cast kits◦ Evaluating the microcontroller

Development Kit◦ More comprehensive◦ For developing the system around the

microcontroller Reference design kits

◦ Application specific reference designs already complete

Evaluation/Development/Reference design kits

Choosing a Microcontroller

Marketing analyzes market needs, Drivers & develops new product specification

Environment sensors, motors, LCD Display, Keypad, etc

Engineering determines what functions of microcontrollers are required to meet specifications

Engineering team searches for MCU & other system components that will deliver end system to specification

Basics of Designing a System

Up Front Design System◦ Spreadsheets◦ Feature Requirements◦ Tool Requirements◦ Evaluation boards

Hardware V/S Software◦ Complexity of MCU

Choosing a microcontroller:General Tips

Features / On chip Peripherals◦ ADC◦ DAC◦ Analog Comparator◦ PWM◦ LCD Control◦ Timers◦ JTAG◦ I/Os

Communication Interface◦ USB◦ CAN◦ UART◦ SPI◦ Others…

Packages◦ Size◦ Pins

Choosing a microcontroller:Parametric aspects

Power◦ Sleep Mode◦ Voltage◦ Current

Speed◦ Clock frequency◦ Critical Instruments◦ Interrupt latency

Reliability◦ Application demand

Memory◦ Size◦ Type

Familiarity◦ Personal experience◦ Senior Engineer

Choosing a microcontroller:Parametric aspects

Price◦ Device◦ Volume◦ Software tools

IDEs Debug Compiler OS

Available Kits◦ Evaluation Kit◦ Development Kit◦ Reference design kits

Support◦ Documentation

White Papers Reference design Example code User Guide Errata

◦ Application Engineers Response time

◦ Community Portability

◦ Roadmap◦ Large Family◦ Abstraction Layer

Choosing a microcontroller:Parametric aspects

Thank You