Embedded C Programming with Real Time Linux (i86) — A 5 day course

Synopsis

This C course is extensive and contains many advanced concepts.

The range of modules covers a full introduction to C, real-time and embedded systems concepts through to the design and implementation of real time embedded or standalone systems based on real-time operating systems and their device drivers. Real time Linux (RTLinux) is used as an example of such a system. The modules include an introduction to the development of Linux device drivers.

Predominantly intended to be taught to development teams at customer sites it is not expected that any one course would cover the full range of modules in a typical five day period.

For teams without experience of C and high-end real time operating sytems it would typically require eight to ten days of intensive training to give full coverage to the topics included here. The course covers all of the important features of the C language as well as a good grounding in the principles and practices of real-time systems development including the POSIX threads (pthreads) specification.

The design of the modules is intended to provide an excellent working knowledge of the C language and its application to serious real time or embedded systems. Those wanting in-depth training specifically on RTLinux or Linux kernel internals should contact us to discuss their requirements; this set of modules is geared more towards providing the groundwork for approaching those domains rather than as in-depth training on a specific approach.

The course contains essential information for anyone developing embedded systems such as microcontrollers, real-time control systems, mobile device, PDAs and similar applications.

This C course is based on many years experience of teaching C, extensive industrial programming experience and also participation in the ANSI X3J11 and BSI standards bodies that produced the standard for C. We focus on the needs of day-to-day users of the language with the emphasis being on practical use and delivery of reliable software.

Each section of the material covered by the tutor is followed by hands-on practical exercises for which worked examples of the solutions are typically provided.

An Introduction to C

Overview
The C Programming Language
The C Standards
The Importance of Standards
A Simple C Program
Comments
Preprocessor Directives
Functions main stdio
Libraries printf
Strings
Return Values
Statements
Review

Introduction to Embedded C Programming

Overview
Embedded C and Standard C
Simple Embedded C Program
Practical — Compiling the Program
Differences Between the Standard and Embedded Versions
Benefits of Using C for Embedded Systems
C in the Embedded Environment
C in the Real Time Linux Environment
Learning Standard C

Variable Types and Constants

Overview
Variables
Basic Variable Types
Other Variable Types
Sizes of Data Types
Declaring Variables
Declaring Multiple Variables
Variable Names
Initialising Variables at Declaration
Character Constants
Named Constants
Boolean Type — Truth Values
Casting — Type Conversion
Decimal, Octal, and Hexadecimal Notations

Operators

Overview
Operators
Expressions
Assignment Operator
Chaining Assignments
Arithmetic Operators
Arithmetic Operators: Division and Remainder
Example of Remainder
Increment and Decrement Operators
Postfix Increment and Decrement
Relational Operators
Logical Negation
Logical Operators
Short-Circuiting
Compound Assignment Operators

Flow Control

Overview
The if Statement
Assignment and Equality
Nested if Statements
Multi-Way if Statements
The for Loop for Loop Syntax
The while Loop
The do-while Loop
Infinite Loops break Statement continue Statement
Conditional Operator switch Statement switch Caveats
Shortened Statements if Statement Trap goto Statement

Functions

Overview
The Rôle of Functions
Function Libraries
Functions — Syntax
Return Values
Function Arguments
Local Variables
Scope and Lifetime
Functions Calling Functions
Call-by-Value
Definition and Declaration
Definition After Use
Prototypes and Old-Style Declarations
Variadic Functions

Arrays

Overview
Array Basics
Array Example
Looping Over an Array
Array Sizes
Copying Arrays
Initialising Arrays
Strings
Array Caveats

Evaluating Expressions

Truth Values
Precedence
Associativity
Operand Evaluation
Casting - Type Conversion
Operator Precedence Table
Operator Precedence Table Continued

Bit Manipulation

Objectives
Introduction
Bit Twiddling Operators
Bit Shifting
Portable Bit Manipulation
Print Bit Representations
Example — Bit Manipulation
Summary

Pointers

Overview
What is a Pointer?
Creating a Pointer
Pointer Types
Uninitialised Pointers
Null Pointers
Pointers as Function Arguments
Pointers and Arrays
Pointer Arithmetic
Using sizeof
Array/Pointer Equivalence
Passing Arrays to Functions
Pointers to Constant Data
Passing Pointers-to-Const
Converting Pointers-to-Const

Other Data Types: Structures, Unions, and Enums

Overview
Defining Structures
Using Structures
Initialising Structure Variables
Problems with Initialising Structures
Initialising Arrays of Structures
Pointers to Structures
Passing Structures to Functions
Passing Structure Pointers
Structures as Data Types
Enumerations
Unions
Discriminating a Union

The Preprocessor and Multiple-File Programs

Overview
Standard Headers
The Preprocessor
The #define Directive
Large Programs
Deciding How to Split a Program
Sharing Declarations
Using Header Files
Writing a Header File
Conditional Compilation
Module-Private Functions
Module-Private Variables
Function-Private Variables
Public Module Variables
When to Use Global Variables

String Handling

Passing Strings to Functions
String Handling
Standard String Functions
Character Classes
Available Character Classes
Letter Case
Converting a String to a Number
Converting a Number to a String
String Input

Real-Time - C Techniques for Dealing with Time

What is Real-Time?
Characteristics of Real-Time Applications
Synchronising I/O with CPU Via Polling
Synchronising I/O with CPU Via Interrupts
Interrupts Capabilities of the 16f877 Pic
Handling Interrupts with C2C
Interrupts in Real Time Linux
Generating Delays Via Software
C Delay Loops
Generating Delays Via Hardware
Generating Delays in RTOS
Example Flash Led Using Timer with Interrupt
Introducing Multi-Tasking
Real-Time Operating Systems
RTLinux Kernel
Scheduling Algorithms

Tasks, Threads, POSIX Pthreads

Basics
Why Tasks?
Multitasking Example
Our Terminology
Processes and Threads Analogy
Synchronisation, Scheduling and Races
Thread Basics
Creating Posix Pthreads
Creating Threads Example
Example of Multiple Threads
Shared Data Problems
Race Conditions
Dealing with Critical Sections
Example of Unprotected Critical Section
Protecting Critical Sections
Drawbacks to Mutexes
Using Condition Variables
Operations on Condition Variables
Semaphores
Spinlocks
Debugging Multithreaded Programs
Thread-Safe Functions
Deadlocks
Priority Inversion

Self-Referential and Dynamic Data Structures

Objectives
Common Data Structures
Circular Buffers
Race Conditions
Singly Linked List
Data Allocation
Using malloc and free Heap allocation example
Details of malloc and free
Supporting Functions
Doubly Linked Lists

Developing on Real Time Linux

Real Time Linux Environment
Typical RTOS Features
Core RTOS Facilities
RTLinux
Architecture of RTLinux Application
Linux Module Example
Compiling and Running Modules
Tiers of Services
Creating a RTLinux Thread
Simple Parallel Port Manipulation
Requesting IO Ports
Measuring Time
Elapsed Time in RTLinux

Interprocess Communication in Real Time Linux

Basics of IPC
FIFOs
Shared Memory in RTLinux
Allocating Shared Memory
User-Level Shared Memory
Shared Memory Thread
Shared Memory Module
IPC Practical
Servo Control Example
Servo Controlled Via IPC
Software Interrupts
Software Interrupt API
Real (Hard) Interrupts
Hard Interrupt Example

Linux Device Drivers

Linux Device Drivers
Driver Types
Device Number
Driver Initialisation
Module Load/Unload
Providing Module Parameters
Open and Release Functions
Read and Write
Write
Reading from Device
Read Code
Tasklet and Bottom Half Code
Interrupt and Tasklet Code

Further Pointers

Pointers to Pointers
Using Pointers to Pointers to Structures
Pointers to Constant Values
Constant Pointers
Increment Operators and Pointers
Pointers to Functions
Initialising Function Pointer Values
Calling Functions Through Pointers
Call-Back Functions
Arrays of Pointers to Functions
Function Pointers for State Machines
State Machine Example: a Toaster

Building Software with Make

Introduction
Different Versions of Make
A Simple Project
Software Building Concepts
Targets and Prerequisites in Make
Building an Object File with Make
Pattern Rule Variables
Building an Executable with Make
Rebuilding When Prerequisites Change
Default Rules
Substitution References
Implicit Rules
Configuring Implicit Rules
Adding More Rules
Advanced Features

Advanced Use of the Preprocessor

Parametric Macros
Problems with Macros
Macros and Scope
Macros and Precedence
Testing Assertions
Stringification
Assertions with Side Effects
Token Pasting
When to Use Parametric Macros

Efficient C Programming

Basics
Principal Causes of Inefficiency
Architecture Issues
Efficient Algorithms
Coding Tactics and Compilers
Difficulties with Code Optimisation
Common Tricks - Subexpressions
Using register Variables
Loop Unrolling
Space-Time Tradeoffs
Floating-Point Arithmetic
Compiler Optimisation
Avoid Pass-by-Value of Large Objects

MISRA C — Designing Safer C Programs

In This Module Will Will Cover:
MISRA C — for Safety-Related Programming
MISRA C - Rules
Environment Rules
Character Sets and Comments
Identifiers and Types
Constants
Declarations and Definitions
Initialisation
Operators
Expressions
Control Flow
Functions
Pre-Processor Directives
Pointers and Arrays
Structures and Unions
Standard Libraries
MISRA C Tools
References for MISRA C and Safer C

Suitable For

Programmers and engineers who already have some understanding of programming and who now wish to gain a solid understanding of the use of C for embedded and real-time systems software development.

Prerequisites

Programming experience

A good understanding of real-time programming issues