Embedded programming Embedded programming (1).pptx

Embedded Systems
By Abebe B.
Embedded programming

Definition of Embedded Systems
Programming
• Embedded systems programming involves
designing and developing software for
embedded systems.
• This software is typically written in low-level
languages such as C and assembly
language and is optimized for the specific
hardware and application requirements of
the system.

Embedded Systems Programming
• Embedded systems programming refers to the
development of software for embedded
systems, which are computer systems that are
integrated into other devices or products.
• These systems are designed to perform specific
functions, and they often have limited
resources, including memory, processing
power, and energy.
• Embedded systems programming is essential
for developing systems that are reliable,
efficient, and cost-effective.

Embedded Languages
 Some of the most commonly used programming languages
for embedded systems programming include:
 C:
• C Programming is a widely used programming language for
embedded systems programming.
• It provides direct access to system resources and is well-suited for
systems with limited resources.
 Assembly language:
• Assembly language is a low-level programming language that
provides direct access to system resources.
• It is often used for systems with very limited resources or for
performance-critical applications.
 C++:
• C++ is a high-level programming language that is often used for
• It provides object-oriented programming features and can be used
to develop complex systems.

Embedded Languages
• More than any other, C has become the
language of embedded programmers.
• This has not always been the case, and it will
not continue to be so forever.
• However, at this time, C is the closest thing
there is to a standard in the embedded world.
– Explain why C ?

Embedded Languages
• It is surprising to find that one language has
proven itself appropriate for both 8-bit and
64-bit processors; in systems with bytes,
kilobytes, and megabytes of memory;
• Of course, C is not without advantages.

Embedded Languages
• C is
– small and fairly simple to learn,
– compilers are available for almost every processor in use today,
and
– there is a very large body of experienced C programmers.
• In addition, it has the benefit of processor-
independence, which allows programmers to
concentrate on algorithms and applications, rather than
on the details of a particular processor architecture.
• However, many of these advantages apply equally to
other high-level languages.
– So why has C succeeded where so many other languages
have largely failed?

Embedded Languages
• Perhaps the greatest strength of C-and the thing that
sets it apart from languages like Pascal and FORTRAN-
is that it is a very "low-level" high-level language.
• C gives embedded programmers an extraordinary
degree of direct hardware control without sacrificing
the benefits of high-level languages.
• The "low-level“ nature of C was a clear intention of the
language's creators.

Embedded Systems Programming
Tools
• Embedded systems programming requires specialized tools to
develop, test, and debug software for these systems.
• These tools include:
– Integrated development environments (IDEs):
• IDEs provide a comprehensive development environment for
• They typically include a code editor, compiler, debugger, and other
tools for developing and testing software.
– Cross-compilers:
• Cross-compilers are used to compile code for a different platform
than the one on which the compiler is running.
– Emulators and simulators:
• Emulators and simulators are used to test software on a virtual
environment that emulates the hardware and software of the target
system.
• They are often used for testing software before it is deployed to the
target system.

Embedded Systems Programming Best
Practices
• Embedded systems programming requires careful attention to
detail and a focus on writing efficient and reliable code.
• To develop software for embedded systems effectively,
developers should follow best practices, including:
– Writing Efficient Code
• Writing efficient code is critical for embedded systems, as these systems
often have limited resources.
• Developers should focus on writing code that is optimized for the specific
hardware and application requirements of the system and should avoid
using unnecessary resources.

Arduino UNO Board
• The Arduino UNO is a standard board of Arduino.
• Arduino UNO is based on an ATmega328P microcontroller. It is easy to use
compared to other boards, such as the Arduino Mega board, etc.
• The board consists of digital and analog Input/Output pins (I/O), shields,
and other circuits.
• The Arduino UNO includes 6 analog pin inputs, 14 digital pins, a USB
connector, a power jack, and an ICSP (In-Circuit Serial Programming)
header.
• The IDE is common to all available boards of Arduino.

Arduino UNO Board
• The Arduino board is shown below:

Arduino UNO Board
• The components of Arduino UNO board are shown below:

Arduino UNO Pinout
• The Arduino UNO Board, with the specification of pins, is shown below:

Your First Embedded Program
• Embedded programmers must be self-reliant. They
must always begin each new project with the
assumption that nothing works-that all they can rely
on is the basic syntax of their programming language.
• Even the standard library routines might not be
available to them. These are the auxiliary functions-
like printf and scanf -that most other programmers
take for granted.

“Hello, World”
• Every embedded system has at least one LED that
could be controlled by software.
• So my substitute for the "Hello, World!" program has
been one that blinks an LED at a rate of 1 Hz (one
complete on-off cycle per second).
• Typically, the code required to turn an LED on and off
is limited to a few lines of C or assembly, so there is
very little room for programming errors to occur.

setup()
• The setup() function is called when a sketch
starts. Use it to initialize variables, pin modes,
start using libraries, etc.
• The setup() function will only run once, after
each powerup or reset of the Arduino board.
Example Code
void setup()
{
// initialize digital pin LED_BUILTIN OR PIN13 as an output.
pinMode(LED_BUILTIN, OUTPUT);
}
void loop() {.......}

loop()
• After creating a setup() function, which
initializes and sets the initial values, the loop()
function does precisely what its name
suggests, and loops consecutively, allowing
your program to change and respond.
• Use it to actively control the Arduino board.
Example Code
void setup() {………..}
void loop() {
digitalWrite(LED_BUILTIN, HIGH);
delay(1000);
digitalWrite(LED_BUILTIN, LOW);
delay(1000); }

“turn an LED on and off”
// the setup function runs once when you press reset or power the board
void setup()
{
// initialize digital pin LED_BUILTIN as an output.
pinMode(LED_BUILTIN, OUTPUT);
}
// the loop function runs over and over again forever
void loop()
{
digitalWrite(LED_BUILTIN, HIGH); // turn the LED ON (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn LED OFF (LOW is the voltage level)
delay(1000); // wait for a second
}

The Role of the Infinite Loop
• One of the most fundamental differences between
programs developed for embedded systems and those
written for other computer platforms is that the
embedded programs almost always end with an
infinite loop.
• Typically, this loop surrounds a significant part of the
program’s functionality-as it does in the Blinking LED
program.
• The infinite loop is necessary because the embedded
software's job is never done. It is intended to be run
until either the world comes to an end or the board is
reset, whichever happens first.

Compiling, Linking, and Locating
The Build Process

The Build Process
• The process of converting the source code
representation of your embedded software into an
executable binary image involves three distinct steps.
– First, each of the source files must be compiled or
assembled into an object file.
– Second, all of the object files that result from the first step
must be linked together to produce a single object file,
called the relocatable program.
– Finally, physical memory addresses must be assigned to the
relative offsets within the relocatable program in a process
called relocation.
– The result of this third step is a file that contains an
executable binary image that is ready to be run on the
embedded system.

The embedded software development
process

process
• Object file:-
– It is a specially formatted binary file that contains the set
of instructions and data resulting from the language
translation process. Although parts of this file contain
executable code, the object file is not intended to be
executed directly.
– There is also usually a symbol table somewhere in the
object file that contains the names and locations of all the
variables and functions referenced within the source file.
– Parts of this table may be incomplete, however, because
not all of the variables and functions are always defined in
the same file.
– These are the symbols that refer to variables and functions
defined in other source files. And it is up to the linker to
resolve such unresolved references.

process
• Each of the steps of the embedded software build
process is a transformation performed by software
running on a general-purpose computer.
• The compiler, assembler, linker, and locator are all
pieces of software that run on a host computer, rather
than on the embedded system itself.
• Yet, despite the fact that they run on some other
computer platform, these tools combine their efforts
to produce an executable binary image that will
execute properly only on the target embedded
system.

The split between host and target

Compiling
• The job of a compiler is mainly to translate
programs written in some human-readable
language into an equivalent set of opcodes for
a particular processor.
• Of course, each processor has its own unique
machine language, so you need to choose a
compiler that is capable of producing
programs for your specific target processor.

Compiling
• In the embedded systems case, this compiler
almost always runs on the host computer. It simply
doesn't make sense to execute the compiler on
the embedded system itself.
• A compiler such as this-that runs on one computer
platform and produces code for another-is called a
cross-compiler.
• The use of a cross-compiler is one of the defining
features of embedded software development.

Linking
• All of the object files resulting from step one
must be combined in a special way before the
program can be executed.
• The object files themselves are individually
incomplete, most notably in that some of the
internal variable and function references have not
yet been resolved.
• The job of the linker is to combine these object
files and, in the process, to resolve all of the
unresolved symbols.

Linking
• The output of the linker is a new object file
that contains all of the code and data from the
input object files and is in the same object file
format.
• It does this by merging the text, data, and bss
sections of the input files.

Locating
• The tool that performs the conversion from relocatable
program to executable binary image is called a locator.
• It takes responsibility for the easiest step of the three.
In fact, you will have to do most of the work in this step
yourself, by providing information about the memory
on the target board as input to the locator.
• The locator will use this information to assign physical
memory addresses to each of the code and data
sections within the relocatable program.
• It will then produce an output file that contains a
binary memory image that can be loaded into the
target ROM.

Getting to Know the Hardware
• Before writing software for an embedded
system, you must first be familiar with the
hardware on which it will run.
• At first, you just need to understand the general
operation of the system.
• Whenever you receive a new board, you should
take some time to read whatever documents
have been provided with it.
• If the board is an off-the-shelf product, it might
arrive with a "User's Guide" or "Programmer's
Manual" that has been written with the
software developer in mind.

Arduino Uno
https://www.electronicshub.org/arduino-uno-pinout/

Importance of Embedded
Systems Programming
• Embedded systems are used in a wide range of
products, including automobiles, medical
devices, consumer electronics, and industrial
equipment.
• These systems must be reliable, efficient, and
cost-effective, and embedded systems
programming plays a critical role in achieving
these goals.
• By optimizing software for the specific hardware
and application requirements of the system,
developers can improve system performance,
reduce energy consumption, and minimize costs.

https://www.arduino.cc/reference/en/

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