Embedded Systems Introduction

Microprocessor building blocks 1. ALU (Arithmetic Logic Unit): The ALU is a sequential logic circuitry that is intended to perform arithmetic and logical operations, such as ADD, SUBTRACT, AND, OR, SHIFT. Example of a primitive ALU (Input, Output, address input or control input) n-bit ALU and n-bit µP 2. Registers: A register is a temporary (internal) storage element

Microprocessor building blocks (contd.) 3. BUSES: The registers and ALU are not permanently connected together, but are joined by a DATA BUS. This bus allows data to be passed from a register to the ALU at one instant and from the ALU to a register at another instant. The bus is, in fact, a parallel set of wires (conductive silicon internal to a chip or tracks on a printed circuit board), which carries information, and which connect all elements together. data bus, address bus and control bus

Microcontrollers vs. Microprocessors Micro controllers are ‘microcomputers on a chip’. optimized to control electronic devices. Usually microcontrollers are used for controlling industrial equipment and machinery and have therefore special instructions as for example bit manipulation instructions. What are the differences between a μC and a μP? Nonvolatile Program and Data MemoriesInternal SRAM A/DAnalog Comparator Internal Calibrated RC OscillatorTimers/Counters External and Internal Interrupt SourcesSleep Modes Serial Peripheral Interface (SPI), USART, Two- wire Serial Interface Watchdog

Microcontrollers and Embedded Systems In control tasks the μC is usually embedded in the system. Embedded systems have minimal requirements for memory and program size and need to communicate with simple inputs and outputs. Keyboards, screens, disks, printers are seldomly needed by an embedded system. Microcontrollers are usually dedicated to one task and run one specific program.

High Level Languages (contd.) High LevelLow Level 1One instruction = many machine code instructions. One instruction = one machine code instruction. 2Portable, task-orientedMachine specific, machine-oriented 3More English-likeLess easy to write and debug.

Machines and appliances that use μC… Television, Satellite Receiver, Monitor, Modem, Router, Printer, Microwave oven, Sound System, Digital Camera, Car (most all of them), Car stereo, Dishwasher, Dryer, Washing Machine, Ovens, Air Conditioner, Cell phone, Digital Multi-Meter, Calculator, Medical Equipment (e.g. Heart Monitors), Traffic Lights, Fax Machines, Copy Machine, Security Systems, Fire Alarms, And MUCH more…. A typical mid range car has as many as 50 or more microcontrollers (e.g. in anti-lock brakes and in cruise control).

Course Contents: Introduction - Microcontrollers and Embedded Systems Memories I_O Ports External Interrupts Timers Clock Options Sleep Modes Reset Sources Reset and Interrupt Vectors Watchdog Timer Communicating Dealing with Analog Signals + Code Vision AVR: C-language Compiler