Lecture 04_05-IoT

C Programming Fundamentals

• Primary Data Types:

  • char or unsigned char: 8-bit

  • int or unsigned int: 16-bit

  • short int: 8-bit

  • long int: 32-bit

  • float: 32-bit

  • double: 64-bit

  • long double: 80-bit

Operators in C

• Mathematical Operators:

  • *: Multiplication

  • /: Division

  • %: Modulus (remainder)

  • +: Addition

  • -: Subtraction

• Relational Operators:

  • <: Less than

  • <=: Less than or equal to

  • >: Greater than

  • >=: Greater than or equal to

  • ==: Equal to

  • !=: Not equal to

• Logical Operators:

  • &&: Logical AND

  • ||: Logical OR

  • !: Logical NOT

• Assignment Operators:

  • =: Assign value

  • +=, -=, *=, /=, %=, <<=, >>=, &=, ^=, |=: Compound assignments

Control Structures

• If Statement Syntax:

  • if (condition) { do this; }

  • if (condition) { do this; } else { do this; }

• Loop Structures:

  • While Loop:

    while(condition) { do this; Increment; }  

  • For Loop:

    for(initial; cond; incr) { do this; }  

State Machine Design and TinkerCAD

• Finite State Machine (FSM) Design for Arduino:

  • Components Required:

    • Inputs: Push Buttons (PB_ON and PB_OFF)

    • Output: LED

  • Design Steps:

    • Identify states (e.g., OFF, ON)

    • Create the hardware design using TinkerCAD

    • Write and test the code

Example State Machine Implementation

1. Declare Pins and States:

   #define LED 2  
   #define Pb_ON 3  
   #define Pb_OFF 4  
   enum states {OFF, ON};  
   states currentstate = OFF;  

2. Setup Function:

   void setup() {  
       pinMode(LED, OUTPUT);  
       pinMode(Pb_OFF, INPUT_PULLUP);  
       pinMode(Pb_ON, INPUT_PULLUP);  
       Serial.begin(9600);  
   }  

3. Loop Function:

   void loop() {  
       switch(currentstate) {  
           case OFF:  
               if(digitalRead(Pb_ON) == LOW) {  
                   currentstate = ON;  
                   digitalWrite(LED, HIGH);  
               }  
               break;  
           case ON:  
               if(digitalRead(Pb_OFF) == LOW) {  
                   currentstate = OFF;  
                   digitalWrite(LED, LOW);  
               }  
               break;  
       }  
   }  

Important Functions and Concepts

• Serial Communication:

  • Serial.begin(9600);: Initializes serial communication at 9600 baud rate

  • Serial.println(variable);: Sends variable data to the Serial Monitor

• Input/Output Management:

  • digitalRead(pin): Reads the value from a specified digital pin

  • digitalWrite(pin, value): Writes a value (HIGH or LOW) to a specified digital pin

• Functional Decomposition:

  • It's often useful to encapsulate repetitive tasks in functions to promote code reuse and organization.

Pull-Up and Pull-Down Resistors

• Pull-Up Configuration:

  • Button pressed = LOW (0)

  • Use Pull-Up Resistors or set pinMode(pin, INPUT_PULLUP) in code.

• Pull-Down Configuration:

  • Button pressed = HIGH (1)

  • Use Pull-Down Resistors or set pinMode(pin, INPUT_PULLDOWN) in code (Arduino Zero family only).