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++);
}
}
