Arduino based Applications-part 6
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The document discusses push button switches and keypads. It provides instructions on how to connect a push button switch and keypad to an Arduino board. For a push button switch, it explains that internally the switch connects two contacts together when pressed to allow electricity to flow. It then gives code to control an LED based on the button press. For keypads, it explains their use in electronic devices for input and shows the row and column arrangement. It provides the components needed and code to read key presses from a 4x4 matrix keypad and display them on the serial monitor.
![Keypad
#include <Keypad.h>
const byte numRows= 4; //number of rows on the keypad
const byte numCols= 4; //number of columns on the keypad
//keymap defines the key pressed according to the row and columns
//just as appears on the keypad
char keymap[numRows][numCols]=
{
{'1', '2', '3', 'A'},
{'4', '5', '6', 'B'},
{'7', '8', '9', 'C'},
{'*', '0', '#', 'D'}
};
12](https://image.slidesharecdn.com/swith-keypad-181130183651/85/Arduino-based-Applications-part-6-12-320.jpg)
![Keypad
//Code that shows the keypad connections to the arduino terminals
byte rowPins[numRows] = {9,8,7,6}; //Rows 0 to 3
byte colPins[numCols]= {5,4,3,2}; //Columns 0 to 3
//initializes an instance of the Keypad class
Keypad myKeypad= Keypad(makeKeymap(keymap), rowPins,
colPins, numRows, numCols);
void setup()
{
Serial.begin(9600);
}
13](https://image.slidesharecdn.com/swith-keypad-181130183651/85/Arduino-based-Applications-part-6-13-320.jpg)
Arduino based Applications-part 6
- 2. Push button Switch Switches are really simple components. When you press a button or flip a lever, they connect two contacts together so that electricity can flow through them. The little tactile switches that are used in our example have four connections, which can be a little confusing. 2
- 3. Push button Switch Actually, there are only really two electrical connections, as inside the switch package pins B and C are connected together, as are A and D. 3
- 4. Push button Switch To build such application, you will need the following Components: • Arduino Uno • USB cable • Push Switch • Jumper Wires • LED • Resistor 4
- 5. Push button –Without Code 5
- 6. Push button –With Code int d=2; // to store on or off value void setup() {pinMode(2,INPUT); pinMode(13,OUTPUT); } void loop() { d=digitalRead(2); if(d==0) {digitalWrite(13,HIGH);} else {digitalWrite(13,LOW);} } 6
- 7. Keypad 7
- 8. Keypad Keypads are used in all types of devices, including cell phones, fax machines, microwaves, ovens, door locks, etc. They're practically everywhere. electronic devices use them for user input. So knowing how to connect a keypad to a microcontroller such as an Arduino is very valuable for building many different types of commercial products. when a key is pressed, it show up at the Serial Monitor on your computer. For this project, the type of keypad we will use is a matrix keypad. The matrix keypad we are using has 16 keys (0-9, A-D, *, #), yet only 8 output pins. 8
- 9. Keypad How the rows and column are arranged inside the keypad is shown in the figure. The Arduino can determine which button was pressed. For example, when key 1 is pressed, column 1 and row 1 are shorted. The Arduino will detect that and input a 1 to the program. 9 R1 R2 R3 R4 C1 C2 C3 C4 R1 R2 R3R4C1C2 C3C4
- 10. Keypad To build such application, you need the following components: • Arduino Uno • USB cable • 4x4 Matrix Keypad • Jumper wires 10
- 11. Keypad 11 Keypad with Arduino Uno connections:
- 12. Keypad #include <Keypad.h> const byte numRows= 4; //number of rows on the keypad const byte numCols= 4; //number of columns on the keypad //keymap defines the key pressed according to the row and columns //just as appears on the keypad char keymap[numRows][numCols]= { {'1', '2', '3', 'A'}, {'4', '5', '6', 'B'}, {'7', '8', '9', 'C'}, {'*', '0', '#', 'D'} }; 12
- 13. Keypad //Code that shows the keypad connections to the arduino terminals byte rowPins[numRows] = {9,8,7,6}; //Rows 0 to 3 byte colPins[numCols]= {5,4,3,2}; //Columns 0 to 3 //initializes an instance of the Keypad class Keypad myKeypad= Keypad(makeKeymap(keymap), rowPins, colPins, numRows, numCols); void setup() { Serial.begin(9600); } 13
- 14. Keypad //If key is pressed, this key is stored in 'keypressed' variable //If key is not equal to 'NO_KEY', then this key is printed out //if count=17, then count is reset back to 0 (this means no key is //pressed during the whole keypad scan process void loop() { char keypressed = myKeypad.getKey(); if (keypressed != NO_KEY) { Serial.print(keypressed); } } } 14
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