Declaring Variables
Declaring a variable is the process of reserving a space in the memory of Arduino for a specific type of data. This is done by combining a type and a name to form a statement. The type determines how much memory needs to be reserved, and the name is used to reference the variable. For example, declaring a Boolean variable called “myVariable” would look like this: Boolean myVariable;
Assigning Values
Once a variable has been declared, it can be assigned a value. This is done by using the assignment operator, which is the equals sign. For example, assigning the value “high” to the variable “myVariable” would look like this: myVariable = high; This statement searches the memory for the variable “myVariable”, grabs the value stored in it, destroys it, and then assigns the new value “high”.
Reading Digital Pins
In order to read a digital pin on Arduino, the digitalRead() function is used. This function takes one parameter, which is the pin number to be read. It then returns either a 0 (LOW) or a 1 (HIGH). For example, to read pin 5 and store the result in the variable “myVariable”, the following code can be used: myVariable = digitalRead(5); This statement reads the value of pin 5, assigns it to the variable “myVariable”, and then stores it in the memory.
Using Variables
Once a variable has been declared and assigned a value, it can be used in any expression. For example, if the variable “myVariable” has been assigned the value “high”, it can be used in an if statement like this: if (myVariable == HIGH) { … } This statement checks to see if the value of “myVariable” is equal to “HIGH”, and if it is, it will execute the code inside the curly braces.
Pin Mode and Serial Begin
The first step in programming the Arduino Uno is to set the pin mode and serial begin. Pin 4 is set as the input, and the serial port rate is set to 9600.
Declaring a Variable
The next step is to declare a new variable, in this case a Boolean. This variable is assigned the value of digital read 4. It is possible to combine these two lines, so that the variable is declared and assigned a value in one line.
Printing the Variable
The content of the variable is printed to the serial monitor. A delay of 1000 milliseconds is added, and the result is uploaded. When pin 4 is connected to ground, the serial monitor displays a value of zero.
Exercise
The exercise is to use a variable to control the onboard LED. Pin 13 is set as an output, and the value of the variable is used to control the LED. A space is added for coding style, though it is not required. When pin 4 is high, the LED turns on, and when pin 4 is low, the LED turns off.
What is a Variable?
A variable is a named memory location used to store data values. Variables are used to store information such as numbers, characters, text, and other types of data. In Arduino Uno programming, variables are declared before use and can be used to store data that can be changed during the course of the program.
Declaring Variables
In Arduino Uno programming, variables must be declared before use. This is done by specifying the data type of the variable followed by the variable name. For example, to declare an integer variable called “myVariable”, the following code can be used:
Int myVariable;
The data type of the variable determines the type of data that can be stored in the variable. Common data types used in Arduino Uno programming include int (integer), float (floating-point number), char (character), and String (text).
Assigning Values to Variables
Once a variable has been declared, it can be assigned a value. This is done by using the assignment operator (=) followed by the value to be assigned. For example, to assign the value 10 to the variable “myVariable”, the following code can be used:
MyVariable = 10;
Variables can also be assigned the value of other variables. For example, to assign the value of the variable “myOtherVariable” to the variable “myVariable”, the following code can be used:
MyVariable = myOtherVariable;
Using Variables
Once a variable has been declared and assigned a value, it can be used in Arduino Uno programming. Variables can be used in expressions, as arguments to functions, and as the return value of functions. For example, the following code uses the variable “myVariable” in an expression:
Int result = myVariable + 10;
In this example, the value of the variable “myVariable” is added to 10 and the result is stored in the variable “result”.
Variables are an essential part of programming with Arduino. They allow data to be stored and used in expressions, and are declared by combining a type and a name. Values can then be assigned to the variable using the assignment operator, and the variable can then be used in expressions. The digitalRead() function can also be used to read digital pins and store the result in a variable.
Variables are an essential part of Arduino Uno programming. They allow data to be stored and manipulated, and are used in expressions, as arguments to functions, and as the return value of functions. Variables must be declared before use and can be assigned a value using the assignment operator.