Keyboard

Expt-1: Interface keyboard with ATMEGA 32

Components required:

Sl. No.	Category	Item name/value	Quantity
1	IC	ATMEGA32	1
2		7805	1
3	Resistor	10K	1
4		330R	1
5	Capacitor	0.1uf	2
6		22pf	2
7		10uf, 24Volt	1
8	Crystal Oscillator	16MHz	1
9	LCD	16X2	1
10	Matrix Keyboard	4X4	1

Model:

Procedure:

1.  Define F_CPU 16000000UL

2.  include <avr/io.h>, <compat/deprecated.h>, <util/delay.h> <avr/interrupt.h>

3.  define E 5 since pin 5 of PORTD is connected to LCD enable pin

4.  define RS 6 since 6 pin of PORTD is connected to LCD RS i.e. “register selection” pin

5.  declare functions

a.  void send_a_command(unsigned char command);

b.  void send_a_character(unsigned char character);

c.  void send_a_string(char *string_of_characters);

d.  declare uint8_t a,b,c,p,q,r,s,i,f,z; char buffer[16];

e.  int key=0; for allocating integer to reset the LCD once it reaches its display limit

f.  int keypressed=0; for integer for storing matrix value

6.  declare PORTB and PORTD as output pins

7.  initialize i=f=z=0;

8.  give delay of 50ms

9.  send_a_command(0x01); to Clear Screen 0x01 = 00000001

10. give delay of 50ms

11. send_a_command(0x38); to tell lcd we are using 8bit command /data mode

12. give delay of 50ms

13. send_a_command(0b00001111); makes LCD SCREEN ON and courser blinking

14. DDRA=0xF0; makes column pins as input and row pins as output

15. _delay_ms(1);

16. PORTA=0x0F;// to power the row ins

17. _delay_ms(1);

18. Infinite loop 1 starts

19. Infinite loop 2 starts

20. if (z>1) break;

21. else if (z>0)

a.  send_a_command(0x80 + 0x40 +0); to move courser to second line.

b.  _delay_ms(50);

c.  send_a_string("Stop "); to display a string

22. else

a.  send_a_command(0x01);//clear lcd

b.  _delay_ms(50);

c.  send_a_command(0x80 +0); to move courser to first line.

d.  _delay_ms(50);

e.  send_a_string("Start ");//display string

23. Infinite loop 3 starts

24. Check true for any of column pins goes low

a.  if PA0 is low assign a=1 else a=0;

b.  if PA1 is low assign b=2 else b=0;

c.  if PA2 is low assign c=4 else c=0;

d.  if a>0 assign keypressed=a;

e.  if b>0 assign keypressed=b;

f.  if c>0 assign keypressed=c;

g.  display keypressed to show column address

h.  break Infinite loop 3 and goto step 25

25. assign DDRA to DDRA bitwise XOR with 0b11111111 to make rows as inputs and columns as output

26. Delay for 10 ms

27. Power the columns

28. Delay for 50 ms

29. Infinite loop 4 starts

30. Check true for any of row pins goes low

a.  If PA4 is low assign p=16 else p=0;

b.  If PA5 is low assign q=32 else q=0;

c.  If PA6 is low assign r=64 else r=0;

d.  If PA7 is low assign s=16 else s=0;

e.  break Infinite loop 4 and goto step 31;

31. if (p>0) assign keypressed to keypressed bitwise OR with p;

a.  else if (q>0) assign keypressed to keypressed bitwise OR with q;

b.  else if (r>0) assign keypressed to keypressed bitwise OR with r;

c.  else if (s>0) assign keypressed to keypressed bitwise OR with s;

32. display keypressed to show row address

33. check for keypressed==0b00010001

a.  if yes display 3, increment key counter and assign initial and final position if z>0

34. check for keypressed==0b00010010

a.  if yes display 2, increment key counter and assign initial and final position if z>0

35. check for keypressed==0b00010100

a.  if yes display 1, increment key counter and assign initial and final position if z>0

36. check for keypressed==0b00011000

a.  if yes display “ ”, increment key counter and assign initial and final position if z>0

37. check for keypressed==0b00100001

a.  if yes display 6, increment key counter and assign initial and final position if z>0

38. check for keypressed==0b00100010

a.  if yes display 5, increment key counter and assign initial and final position if z>0

39. check for keypressed==0b00100100

a.  if yes display 4, increment key counter and assign initial and final position if z>0

40. check for keypressed==0b00101000

a.  if yes display “ ”, increment key counter and assign initial and final position if z>0

41. check for keypressed==0b01000001

a.  if yes display 9, increment key counter and assign initial and final position if z>0

42. check for keypressed==0b01000010

a.  if yes display 8, increment key counter and assign initial and final position if z>0

43. check for keypressed==0b01000100

a.  if yes display 7, increment key counter and assign initial and final position if z>0

44. check for keypressed==0b01001000

a.  if yes display “ ”, increment key counter and assign initial and final position if z>0

45. check for keypressed==0b10000001

a.  if yes display #, increment key counter and assign initial and final position if z>0

46. check for keypressed==0b10000010

a.  if yes display 0, increment key counter and assign initial and final position if z>0

47. check for keypressed==0b10000100

a.  if yes display *, increment key counter and assign initial and final position if z>0

48. check for keypressed==0b10001000

a.  if yes display “ ”, increment key counter and assign initial and final position if z>0

49. reset keypressed to 0;//after showing integer erasing the row column memory

50. assign DDRA to DDRA bitwise XOR with 0b11111111 to make columns as inputs and rows as output

51. Delay for 10 ms

52. Power the rows

53. Delay for 50 ms

54. Increment z++;

55. If (z>1) break Infinite loop 2 else goto step 19;

56. Reset z to 0;

57. Continue Infinite loop 1

58. return(0);

59. end

void send_a_command(unsigned char command)

{

PORTB = command;

PORTD &= ~ (1<<RS); //putting 0 in RS to tell lcd we are sending command

PORTD |= 1<<E; //telling lcd to receive command /data at the port

_delay_ms(50);

PORTD &= ~1<<E;//telling lcd we completed sending data

PORTB= 0;

}

void send_a_character(unsigned char character)

{

PORTB= character;

PORTD |= 1<<RS;//telling LCD we are sending data not commands

PORTD |= 1<<E;//telling LCD to start receiving command/data

_delay_ms(50);

PORTD &= ~1<<E;//telling lcd we completed sending data/command

PORTB = 0;

}

void send_a_string(char *string_of_characters)

{

while(*string_of_characters > 0)

{

send_a_character(*string_of_characters++);

}

}

Code:

#ifndef F_CPU

#define F_CPU 16000000UL

#endif

#include <avr/io.h>

#include <compat/deprecated.h>

#include <util/delay.h>

#include <avr/interrupt.h>

#define E 5 //giving name “enable” to 5 pin of PORTD, since it Is connected to LCD enable pin

#define RS 6 //giving name “register selection” to 6 pin of PORTD, since is connected to LCD RS pin

void send_a_command(unsigned char command);

void send_a_character(unsigned char character);

void send_a_string(char *string_of_characters);

int main()

{

uint8_t a,b,c,p,q,r,s,i,f,z;

char buffer[16];

int key=0;//allocating integer to reset the LCD once it reaches its display limit

int keypressed=0;//integer for storing matrix value

DDRB = 0xFF;

DDRD = 0xFF;

_delay_ms(50);

i=f=z=0;

_delay_ms(50);//giving delay of 50ms

// make sure to make OC0 pin (pin PB3 for atmega32) as output pin

//putting portB and portD as output pins DDRD = 0xFF;

_delay_ms(50);//giving delay of 50ms

send_a_command(0x01); //Clear Screen 0x01 = 00000001

_delay_ms(50);

send_a_command(0x38);//telling lcd we are using 8bit command /data mode

_delay_ms(50);

send_a_command(0b00001111);//LCD SCREEN ON and courser blinking

DDRA=0xF0;//taking column pins as input and row pins as output

_delay_ms(1);

PORTA=0x0F;// powering the row ins

_delay_ms(1);

while(1)// Infinite loop 1 starts

{

while(1)// Infinite loop 2 starts

       {

if (z>1)

{

       break;

}     

else if (z>0)

{

send_a_command(0x80 + 0x40 +0);//move courser to second line.

_delay_ms(50);

send_a_string("Stop ");//display string

}

else

{

send_a_command(0x01);//clear lcd

_delay_ms(50);

send_a_command(0x80 +0);//move courser to first line.

_delay_ms(50);

send_a_string("Start ");//display string

}

while (1)//   Infinite loop 3 starts

{

if (bit_is_clear(PINA,0)|bit_is_clear(PINA,1)|bit_is_clear(PINA,2))//in any of column pins goes low execute the loop

{

       if(bit_is_clear(PINA,0))

       a=1<<PA0;

       else a=0;

       if (bit_is_clear(PINA,1))

       b=1<<PA1;

       else b=0;

       if (bit_is_clear(PINA,2))

       c=1<<PA2;

       else c=0;

       if (a>0)

       keypressed=a;

       else if (b>0)

       keypressed=b;

       else if (c>0)

       keypressed=c;

itoa(keypressed,buffer,16);

send_a_string(buffer);

//_delay_ms(1);

send_a_string("-");

//_delay_ms(1);

break;

}

}//    Infinite loop 3 stops

PORTA=0xFF;

_delay_ms(50);

DDRA ^=0b11111111;//making rows as inputs and columns as output

_delay_ms(10);

PORTA = 0xF0;//powering columns

_delay_ms(50);

       while(1)//    Infinite loop 4 starts

       {

       if (bit_is_clear(PINA,4)|bit_is_clear(PINA,5)|bit_is_clear(PINA,6)|bit_is_clear(PINA,7))

       {

       if(bit_is_clear(PINA,4))

       p=1<<PA4;

       else p=0;

       if (bit_is_clear(PINA,5))

       q=1<<PA5;

       else q=0;

       if (bit_is_clear(PINA,6))

       r=1<<PA6;

       else r=0;

       if (bit_is_clear(PINA,7))

       s=1<<PA7;

       else s=0;

       break;

       }

       }             //     Infinite loop 4 stops

       if (p>0)

       keypressed|=p;

       else if (q>0)

       keypressed|=q;

       else if (r>0)

       keypressed|=r;

       else if (s>0)

       keypressed|=s;

itoa(keypressed,buffer,16);

send_a_string(buffer);

_delay_ms(1);

send_a_string("/");

_delay_ms(1);

if (keypressed==0b00010001)//

{

send_a_string("3");//if row1 and column1 is high show “1”

key++;

if(z>0)

f=3;

else i=3;

}

if (keypressed==0b00010010)

{

send_a_string("2");// if row1 and column2 is high show “4”

key++;

if(z>0)

f=2;

else i=2;

}

if (keypressed==0b00010100)

{

send_a_string("1");// if row1 and column3 is high show “7”

key++;

if(z>0)

f=1;

else i=1;

}

if (keypressed==0b00011000)

{

send_a_string(" ");//if row1 and column4 is high show “*”

key++;

}

if (keypressed==0b00100001)

{

send_a_string("6");// if row2 and column1 is high show “2”

key++;

if(z>0)

f=6;

else i=6;

}

if (keypressed==0b00100010)

{

send_a_string("5");// if row2 and column2 is high show “5”

key++;

if(z>0)

f=5;

else i=5;

}

if (keypressed==0b00100100)

{

send_a_string("4");// if row2 and column3 is high show “8”

key++;

if(z>0)

f=4;

else i=4;

}

if (keypressed==0b00101000)

{

send_a_string(" ");// if row2 and column4 is high show “0”

key++;

}

if (keypressed==0b01000001)

{

send_a_string("9");

key++;

if(z>0)

f=9;

else i=9;

}

if (keypressed==0b01000010)

{

send_a_string("8");

key++;

if(z>0)

f=8;

else i=8;

}

if (keypressed==0b01000100)

{

send_a_string("7");

key++;

if(z>0)

f=7;

else i=7;

}

if (keypressed==0b01001000)

{

send_a_string(" ");

key++;

}

if (keypressed==0b10000001)

{

send_a_string("#");

key++;

}

if (keypressed==0b10000010)

{

send_a_string("0");

key++;

}

if (keypressed==0b10000100)

{

send_a_string("*");

key++;

}

if (keypressed==0b10001000)

{

send_a_string(" ");

key++;

}

keypressed=0;//after showing integer erasing the row column memory

PORTA=0xFF;

_delay_ms(500);

DDRA ^=0b11111111;//shifting input and power port

_delay_ms(10);

PORTA = 0x0F;//powering row pins of keypad

_delay_ms(50);

z++;

if(z>1)

{

       break;

}

}//    Infinite loop 2 stops

z=0;

}      //     Infinite loop 1 stops

return(0);          

}

      

void send_a_command(unsigned char command)

{

PORTB = command;

PORTD &= ~ (1<<RS); //putting 0 in RS to tell lcd we are sending command

PORTD |= 1<<E; //telling lcd to receive command /data at the port

_delay_ms(50);

PORTD &= ~1<<E;//telling lcd we completed sending data

PORTB= 0;

}

void send_a_character(unsigned char character)

{

PORTB= character;

PORTD |= 1<<RS;//telling LCD we are sending data not commands

PORTD |= 1<<E;//telling LCD to start receiving command/data

_delay_ms(50);

PORTD &= ~1<<E;//telling lcd we completed sending data/command

PORTB = 0;

}

void send_a_string(char *string_of_characters)

{

while(*string_of_characters > 0)

{

send_a_character(*string_of_characters++);

}

}