ARM-LPC1768-Interface a 4x4 keyboard and display the key code on an LCD

ARM-Interface a 4x4 keyboard and display the key code on an LCD

Program

 /** @brief When key is pressed, corresponding key is displayed on LCD
* @Connections :
  * D0 (LCD) -> P1.19
* D1 (LCD) -> P1.20
* D2 (LCD) -> P1.21
* D3 (LCD) -> P1.22
* D4 (LCD) -> P1.23
  * D5 (LCD) -> P1.24
  * D6 (LCD) -> P1.25
  * D7 (LCD) -> P1.26
  * RS (LCD) -> P1.27
* EN (LCD) -> P1.28
  * C1 (Keypad) -> P2.0
* C2 (Keypad) -> P2.1
* C3 (Keypad) -> P2.2
* C4 (Keypad) -> P2.3
  * R1 (Keypad) -> P2.4
* R2 (Keypad) -> P2.5
* R3 (Keypad) -> P2.6
* R4 (Keypad) -> P2.7
*/

#include <lpc17xx.h>
#include "LCD.h"
#include "keypad.h"

char keypad(void);
char c;

/* start the main program */
int main()
{
/* Initialize the GPIO pins for LCD */
/* PORT1 D0,                D7, RS, EN */
LCD_Init(19, 20, 21, 22, 23, 24, 25, 26, 27, 28);
delay(100);

/* Initialize the GPIO pins for Keypad */
/* PORT2    C1         R1         */
Keypad_Init(0, 1, 2, 3, 4, 5, 6, 7);
delay(100);

/* Set LCD parameters like contrast, backlight, cursor position etc */
CMD_WRT(0x38); 
CMD_WRT(0x0f);                         
CMD_WRT(0x06); 
CMD_WRT(0x01);

delay(100);

CMD_WRT(0X01);
CMD_WRT(0X80);
LCD_WRT("----RDL--");
CMD_WRT(0XC0);

  while(1)
  {
/* get the key pressed */
c = keypad();

/* write the key to LCD */
DATA_WRT(c);

delay(100);
}
}

Hardware Connection

D0 (LCD) -> P1.19

D1 (LCD) -> P1.20

D2 (LCD) -> P1.21

D3 (LCD) -> P1.22

D4 (LCD) -> P1.23

D5 (LCD) -> P1.24

D6 (LCD) -> P1.25

D7 (LCD) -> P1.26

RS (LCD) -> P1.27

EN (LCD) -> P1.28             

                                C1 (Keypad on development board) -> P2.0

C2 (Keypad on development board) -> P2.1

C3 (Keypad on development board) -> P2.2

C4 (Keypad on development board) -> P2.3

R1 (Keypad on development board) -> P2.4

R2 (Keypad on development board) -> P2.5

R3 (Keypad on development board) -> P2.6

R4 (Keypad on development board) -> P2.7

Output

When the Key is pressed, Corresponding key is displayed on the LCD. For example, if key ‘1’ is pressed, on LCD it should show “Key Pressed is 1”

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