Processors in Embedded Systems

Processors in Embedded Systems

A Processor in an Embedded Systems contains two essential parts

* Control Unit – Which fetches the instruction from the system memory

* Execution unit

Arithmetic and Logic Unit is also the part of Execution Unit

It performs Data Transfer and data conversion operations

Types of processors

General Purpose Processors (GPP)

  • Microprocessor

  • Microcontroller

  • Digital Signal Processors (DSPs)

  • Media Processors

    • useful for sound and image processing applications

Application Specific System Processors

The processors which are relevant to a particular application like

  • Digital TV

  • HDTV decoders

  • Set Top Boxes

  • DVD Player

Important considerations while selecting a processor

  • Instruction Set

  • Maximum bits in an operand like (8 or 16 or 32 bit)

  • Clock frequency in MHz and processing speed in MIPS (Millions of Instructions per second)

  • ability to solve the complex algorithms used in meeting the deadline for their processing

Microprocessors

It is a VLSI Chip which has a Central Processing Unit (CPU), which may have some optional components like Cache memory, Floating Point Unit (FPU),etc.

Microcontrollers

Microcontroller contains functional circuits and application specific circuits

Functional Circuits are

  • Microprocessor

  • Memory (RAM, ROM, Flash)

  • Timer (Also Watch Dog Timer)

  • Interrupt Controller

  • I/O Ports (Parallel Ports )

  • UART for Serial Communication.

Application Specific Circuits

  • LAN Controllers

  • DMA Controller (Direct Memory Access)

  • Printer Controller

  • Analog to Digital Converter (ADC)

  • Digital to Analog Converter (DAC)

  • Modem

but now a days, lot of embedded systems comes with ADC, DAC,Modem and DMA Controllers.



Digital Signal Processors

  • They are useful in developing applications like Video, audio signal processing,
  • Analog signals like ECG, EEG, Seismic Signals, etc are all processed using Digital Signal Processors.
  • Most of the DSPs are inbuilt with MAC Units (Multiply and Accumulate Units)
  • Texas instruments TM series are some of the example of DSPs

Introduction to Embedded Systems

Definition:
The Combination of Software and Hardware in which the software controls the entire hardware for a dedicated application.

Components of an Embedded Systems
* Power Supply and Reset circuit
* Timer
* Watch Dog Timer or WDT
* Processor
* Memory
RAM Which stores the data (data Memory)
ROM Which stores the Program (Program Memory)
* Interrupt controllers
* IO Ports
* UART for Serial communication
* Parallel ports

Classification of Embedded Systems

Small Scale Embedded Systems
* Uses 8 or 16 bit microcontrollers
* Software and harware complexity is very less
* uses C as a programming language
* The codes are cross compiled and stored in the system memory.
* They sometimes may be battery operated.
Example processors : Intel 8051, Microchip PIC16f8X, Motorola 68HC05,08

Medium Scale Embedded Systems
* Uses 16 or 32 bit controllers or sometime uses DSPs(Digital Signal Processors) or RISC (Reduced Instruction Set Processors)
* They have great complexity.
* They use a Real Time Operating Systems (RTOS), SImulators, Debuggers, emulators, and IDE to develop all these functionalities.
Example: Intel 8051, 80251,80196 Motorola 68HCX11,12

Large Scale Embedded Systems
* They use 32 bit processors.
* They use CPLDs or FPGAs or ASICs
* They are System on Chip Controllers
* They go from initial design like co design and co analysis and co verification
* The Processing speeds are very high in these systems.
* They sometime may be proprietary systems in which the development tools may not be available at all.
Example: ARM7, IBM Power PC

Syllabus – 05BCE403-Embedded Systems

L T P C

3 0 0 3

Aim: The subject aims to cover the concepts of embedded systems, their design and applications, programming models and Interprocess communication.

Objectives: The student would be able to understand and use in embedded systems, device drivers, software engineering practices in embedded systems development and Inter process communication.

Introduction to Embedded Systems: Processor in the System – Software Embedded into a system – Exemplary Embedded Systems – Embedded System-On-chip and in VLSI Circuit Processor and Memory Organization – Structural Units in a Processor – Processor Selection for an Embedded System – Memory Devices – Memory Selection for an Embedded System – Allocation of Memory to Program Segments and Blocks and Memory Map of a System – Direct Memory Access – Interfacing Processor, Memories and I/O Devices.

Devices and Buses for Device Networks: I/O Devices – Timer and Counting Devices – Serial Communication Using the I2 C, ‘CAN’ and Advanced I/O Buses between the Networked Multiple Devices – Host System or Computer Parallel Communication between the Networked I/O Multiple Devices Using the ISA, PCI, PCI – X and Advanced Buses

Device Drivers and Interrupts Servicing Mechanism: Device Drivers – Parallel Port Device Drivers in a System – Serial Port Device Drivers in a System – Device Drivers for Internal Programmable Timing Devices – Interrupt Servicing (Handling) Mechanism – Context and the periods for Context – Switching, Deadline and Interrupt Latency

Program Modeling Concepts: Single and Multiprocessor Systems Software – Development Process- Modeling Processes for Software Analysis Before Software Implementation – Programming Models for Event Controlled or Response Time Constrained Real Time Programs – Modeling of Multiprocessor Systems

Software Engineering Practices: Embedded Software Development Process-Software Algorithm Complexity – Software Development Process Life Cycle and its Models – Software Analysis – Software Design – Software Implementation – Software Testing, Validating and Debugging – Real Time Programming Issues During the Software Development Process – Software Project Management – Software Maintenance –Unified Markup Language (UML) – Interprocess Communication & Synchronization of processes, Task & Threads – Multiple processes in an Application – Problems of Sharing Data by Multiple Tasks & Routines – Interprocess Communication.

TEXTBOOK:
1. Rajkamal, “Embedded Systems-Application, Practice & Design”, Tata McGraw Hill, 2003

REFERENCE BOOKS:

1. Arnold S. Berger, “Embedded Systems Design”, CMP Books, 1997