Embedded
Software is a key element in every embedded project that is used to run the
micro-controller to perform the desired operations. In our daily life, we
frequently use many electronic devices such as washing machines, refrigerators,
mobile phones, security system, digital camera
so on which will be controlled using embedded C program. If you press a button
to take a photo with your digital camera, then micro-controller will perform
the functions essential to capture the image and store it. This article
presents basics of embedded systems to construct the embedded C programming
tutorial.
The
embedded C programming is a collection of one or more functions. Every function
is a collection of statements that are used to perform some specific tasks. The
embedded C programming tutorial is similar to a C language is constructed with
some basic elements such as character set, variables, constants, data types,
keywords, variable declaration, statements, expressions etc. that are used to
write the program easily. However, we are providing 7-steps with embedded C programming tutorial
to easily write the program such as:
Ø Comments
Ø Preprocessor
directives
Ø Port
configuration
Ø Global
variables
Ø main()
function or core function
Ø Variable
declaration
Ø Program
Logic
Ø
7
Steps to Build Embedded C Programming Tutorial
Ø Step1: Comments
The
comments are important to the programming languages which describes function of
program. Comments are non-executable code that is used to provide documentation
to the program. The comments make an easy way to understand function of the
program. There are two types of comments in embedded C programming tutorial
such as:
ü Single
Line Comment
ü Double
Line Comment or Multi Line Comment
ü Single
Line Comment
Generally
single line comments are useful for the programming languages that can be used
to explain a part of the code. The single line comments starts with double
slash(//) which can be placed anywhere in the program. Single line comments are
used to ignore complete line in a program.
ü Single
Line Comment
ü Multi
Line Comment
The
multi line comments starts with single slash and an asterisk (/*) that can be
used to explain a block of code. The multi line comments can be placed any
where in the program. The multi line comments are used to ignore a complete
block of code in a program.
ü Multi
Line Comment
Ø Step2: Processor Directives
ü Preprocessor
directives are lines integrated in the code of programs which can be followed
by a hash sign (#). These lines are not programmed statements, but directives
for the preprocessor. The preprocessor inspects the code before actual
compilation of code begins and resolves all these directives before any code is
actually generated by regular statements. Even though there are many different
preprocessor directives, but two directives are very useful in the embedded C
programming tutorial such as
ü #include
ü #define
Which
can be called as a header file, containing C declarations and macro definitions
to be shared between several source files? The #include directive is normally
used to include standard library such as study. h that can be used to access
I/O functions from the C library. The #define
directive normally used to define the string of variables and to assign the
values by performing the operations in a single instruction it can be defined
as macros.
Ø Step 3:Port Configuration
In
every micro-controller consists of many ports, each port contains many pins
which can be used to control the interfacing devices.
These pins are declared in a program using keywords. The embedded C has consist
standard and predefined keywords such as bit, sbit, SFR which can be used to
declare the single pin and bits in a program.
ü Port Configuration
ü sbit:
This
data type is used in case of accessing a single bit of SFR register.
Syntax: sbit
variable name = SFR bit ;
Ex: sbit a=P2^1;
Explanation:
If we assign p2.1 as ‘a’ variable, then we can use ‘a’ instead of p2.1 anywhere
in the program, which reduces the complexity of the program.
ü Bit:
This
data type is used for accessing the bit addressable memory of RAM (20h-2fh).
Syntax: name of bit variable;
Ex: bit c;
Explanation: It is a bit sequence setting in a small
data area that is used by a program to remember something.
ü SFR:
This
data type is used to get the SFR register peripheral pots by another name. All
the SFR registers must be declared with capital letters.
Syntax: SFR
variable name = SFR address of SFR register;
Ex: SFR
port0=0×80;
Explanation:
If we assign 0×80 as ‘port0’, then we can use 0×80 instead of port0 anywhere in
the program, which reduces the complexity of the program.
ü SFR Register:
‘Special
Function Register’ is represented as SFR register. Microcontroller 8051 has
256 bytes of RAM memory, which is separated into two parts: the first part of
128 bytes is used for data storage, and the other of 128 bytes is used to SFR
registers. All peripheral devices like timers and counters, I/O ports are
stored in the SFR register, and each element has a unique address.
Ø Step4: Global Variables
The
variable declared before the main function is called a global variable, that
can be accessed on any function in the program. The life time of the global
variable depends on the program until program comes to an end.
Ø Step5: Main Function or Core
Function
The
main function is a core of every program execution, starts with main function
only. Every program uses only one main function because if program contains
more than one main function, then the compiler will get confused where to start
the program execution.
ü Main Fucntion
Ø Step6: Variable Declaration
The
variable is a name that can be used to store the values. That variable must be
declared before used in the program. The declaration of a variable specifies
its name and data type. The storage representation of data is called data type.
The embedded C programming uses four basic data types such as float, integer,
character, etc. used to store the data in the memory. The size and range of
data type defined based on compiler.
ü Variable
Declaration
Ø Step7: Program Logic
The
plan of path is called a program logic that presents the theory behind and
expected outcomes of a program’s actions. It describes the assumption or theory
about why the program will work, showing the acknowledged effects of activities
or resources.
ü Program Logic
ü LED flash light Program
Ø LED
flash light Program
Hope
this article gives basic information to the beginners of embedded C
programming. Good understanding of the Embedded C programming is most essential
for designing embedded
based projects. We encourage and welcome queries,
suggestions and comments from our readers. Therefore, you can post your queries
and feedback about this article in the comments section given below.
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