Making Embedded Systems by White, Elecia -- Read -- Imperial Library of Trantor

Index

Making Embedded Systems

Preface

About This Book

About the Author Acknowledgments

Organization of This Book Conventions Used in This Book

Typography Terminology

Using Code Examples Safari® Books Online How to Contact Us

1. Introduction

Compilers, Languages, and Object-Oriented Programming Embedded System Development

Debugging More Challenges Principles to Confront Those Challenges

Further Reading

2. Creating a System Architecture

Creating System Diagrams

The Block Diagram Hierarchy of Control Layered View

From Diagram to Architecture

Encapsulate Modules Delegation of Tasks Driver Interface: Open, Close, Read, Write, IOCTL Adapter Pattern Getting Started with Other Interfaces Example: A Logging Interface

Typical calls needed for logging State of logging Pattern: Singleton Sharing private globals

A Sandbox to Play In Further Reading

3. Getting Your Hands on the Hardware

Hardware/Software Integration

Ideal Project Flow Board Bring-Up

Reading a Datasheet

Datasheet Sections You Need When Things Go Wrong Important Text for Software Developers Evaluating Components Using the Datasheet

Your Processor Is a Language Reading a Schematic Having a Debugging Toolbox (and a Fire Extinguisher)

Keep Your Board Safe Toolbox Digital Multimeter Oscilloscopes and Logic Analyzers

Setting up a scope

Testing the Hardware (and Software)

Building Tests Flash Test Example

Test 1: Read existing data Test 2: Byte access Test 3: Block access Test wrap-up

Command and Response

Creating a command Invoking a command

Command Pattern

Dealing with Errors

Consistent Methodology Error-Handling Library Debugging Timing Errors

Further Reading

4. Outputs, Inputs, and Timers

Toggling an Output

Starting with Registers Set the Pin to Be an Output Turn On the LED Blinking the LED Troubleshooting

Separating the Hardware from the Action

Board-Specific Header File I/O-Handling Code Main Loop Facade Pattern

The Input in I/O

A Simple Interface to a Button

Momentary Button Press

Interrupt on a Button Press Configuring the Interrupt Debouncing Switches

Runtime Uncertainty

Dependency Injection

Using a Timer

Timer Pieces Doing the Math A Long Wait Between Timer Ticks Using the Timer

Using Pulse-Width Modulation Shipping the Product Further Reading

5. Managing the Flow of Activity

Scheduling and Operating System Basics

Tasks Communication Between Tasks Avoiding Race Conditions Priority Inversion

State Machines

State Machine Example: Stoplight Controller State-Centric State Machine State-Centric State Machine with Hidden Transitions Event-Centric State Machine State Pattern Table-Driven State Machine Choosing a State Machine Implementation

Interrupts

An IRQ Happens

Multiple sources for one interrupt Interrupt priority Nested interrupts Nonmaskable interrupts

Save the Context

Calculating system latency Reentrant functions

Get the ISR from the Vector Table

Initializing the vector table Looking up the ISR

Calling the ISR

Disabling interrupts Critical sections

Restore the Context When to Use Interrupts

How Not to Use Interrupts

Polling System Tick Time-Based Events A Very Small Scheduler

Watchdog Further Reading

6. Communicating with Peripherals

The Wide Reach of Peripherals

External Memory Buttons and Key Matrices Sensors

Analog sensors Digital sensors

Actuators

Motors Position encoding PID control

Displays

Segmented displays Pixel displays

So Many Ways of Communicating

Serial

RS-232 and TTL SPI I2C 1-wire USB Miscellaneous other protocols

Parallel Ethernet and WiFi

Putting Peripherals and Communication Together

Data Handling

Circular buffers Hardware FIFOs Direct memory access Comparison of buffering schemes

Adding Robustness to the Communication

Version everything and then checksum it Authentication and encryption

Changing Data Changing Algorithms

Further Reading

7. Updating Code

Onboard Bootloader Build Your Own Updater

Modifying the Resident Updater

Brick Loader

Copy Loader to RAM Run the Loader Copy New Code to Scratch Dangerous Time: Erase and Program Reset to New Code

Security Linker Scripts Summary

8. Doing More with Less

Code Space

Reading a Map File (Part 1) Process of Elimination Libraries Functions and Macros Constants and Strings

RAM

Remove malloc Reading a Map File (Part 2) Registers and Local Variables

Function parameters Minimize scope Look at the assembly

Function Chains Pros and Cons of Globals Memory Overlays

Speed

Profiling

I/O lines and an O-scope Timer profiler 1 (function timer) Timer profiler 2 (response timer) Sampling profiler

Optimizing

Memory timing Variable size One last look at function chains Consider the instructions Reduce math in loops Loop unrolling Lookup tables Coding in assembly language

Summary Further Reading

9. Math

Identifying Fast and Slow Operations

Taking an Average

Use an Existing Algorithm Designing and Modifying Algorithms

Factor Polynomials Taylor Series Dividing by a Constant Scaling the Input Lookup Tables

Implicit input Linear interpolation Explicit input in the table

Fake Floating-Point Numbers

Rational Numbers Precision Addition (and Subtraction) Multiplication (and Division) Determining the Error

Further Reading

10. Reducing Power Consumption

Understanding Power Consumption Turn Off the Light When You Leave the Room

Turn Off Peripherals Turn Off Unused I/O devices Turn Off Processor Subsystems Slowing Down to Conserve Energy

Putting the Processor to Sleep

Interrupt-Based Code Flow Model A Closer Look at the Main Loop Processor Watchdog Avoid Frequent Wake-Ups Chained Processors

Further Reading

Index About the Author Colophon

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