Control structures and functions are essential building blocks in embedded C programming. They enable decision-making, repetitive tasks, and code organization. These tools allow developers to create efficient and flexible programs for microcontrollers and other embedded systems.

Conditional statements, loops, and functions work together to create complex behaviors in embedded systems. By mastering these concepts, you can write more sophisticated programs that respond to various inputs and conditions, making your embedded projects more robust and versatile.

Conditional Statements and Loops

Conditional Statements and Switch-Case

• Conditional statements allow the program to make decisions and execute different code blocks based on whether a condition is true or false
  • if statement evaluates a condition and executes a block of code if the condition is true
  • if-else statement executes one block of code if the condition is true and another block if the condition is false
  • else if statement allows for multiple conditions to be checked in a sequence until one evaluates to true
• Nested conditional statements involve placing one conditional statement inside another, allowing for more complex decision-making logic
• Conditional operators (&&, ||, !) can be used to combine or negate conditions in conditional statements
  • && (logical AND) evaluates to true if both conditions are true
  • || (logical OR) evaluates to true if at least one condition is true
  • ! (logical NOT) negates the result of a condition
• Switch-case statements provide an alternative to using multiple if-else statements when comparing a variable against multiple possible values
  • The switch keyword is followed by the variable to be compared, and each possible value is represented by a case label
  • The break statement is used to exit the switch-case block after a matching case is found and its associated code is executed
  • The default case is optional and executed if no matching case is found

Loops

• Loops allow a block of code to be executed repeatedly until a certain condition is met
• for loop is used when the number of iterations is known in advance
  • Consists of an initialization, a condition, and an update statement
  • The loop continues as long as the condition remains true
• while loop executes a block of code as long as a given condition is true
  • The condition is checked before each iteration
  • Useful when the number of iterations is not known in advance
• do-while loop is similar to a while loop, but the condition is checked after each iteration
  • Guarantees that the loop body is executed at least once, even if the condition is initially false
• Nested loops involve placing one loop inside another, allowing for more complex repetitive tasks
  • Commonly used for traversing multi-dimensional arrays or performing operations on multiple sets of data
• Loop control statements (break, continue) can alter the normal flow of a loop
  • break statement immediately terminates the loop and transfers control to the next statement after the loop
  • continue statement skips the remaining code in the current iteration and proceeds to the next iteration

Functions

Function Prototypes and Inline Functions

• Function prototypes declare the function's name, return type, and parameter list without providing the actual implementation
  • Allows the compiler to check for proper function usage and catch errors before the full definition is encountered
  • Enables modular programming by separating the function declaration from its definition
• Function prototypes are typically placed in header files (.h) to be included in multiple source files
• Inline functions are small functions whose body is directly inserted (inlined) at the point of the function call during compilation
  • Eliminates the overhead of function calls and can improve performance for frequently called small functions
  • Declared using the inline keyword before the function definition
  • Suitable for short, simple functions that are called frequently

Recursive Functions and Interrupt Service Routines (ISRs)

• Recursive functions are functions that call themselves within their own definition
  • Useful for solving problems that can be divided into smaller, similar subproblems (Fibonacci sequence, factorial calculation)
  • Each recursive call operates on a smaller subset of the problem until a base case is reached, at which point the recursion stops and the results are combined
  • Recursive functions must have a well-defined base case to avoid infinite recursion
• Interrupt Service Routines (ISRs) are special functions that are executed in response to hardware or software interrupts
  • Interrupts are signals that temporarily halt the normal execution of the program and transfer control to the corresponding ISR
  • ISRs are used to handle time-critical events (timer overflows, external interrupts from sensors or peripherals)
  • ISRs have specific naming conventions and are declared with the __interrupt keyword followed by the interrupt vector name
  • Within an ISR, it is important to keep the code concise and avoid lengthy operations that may delay the servicing of other interrupts