matrix keyboard password system

[rajrahul2391]

hello friends,
i m working on 2*2 matrix keyboard system ,in which a password is to be set to open a door (device).can any body suggest me a simple code for that.
thanks in advance .

 

[dilraj.n]

hi,
for interfacing 2 * 2 matrix keypad(4 switch) you require 4 IO lines. so you can connect each switch in each line and read the status of that line

 

[rajrahul2391]

that's right sir but i could be able to put password correctly plz give me direction by suitable code.....

 

[dilraj.n]

Which microcontroller you are using?

 

[rajrahul2391]

P89v51RD2 (Philips)

 

[Briez]

Look at this tutorial and 4x4 matrix keypad interfacing and try to make program for only 4 keys as per your requirement.

https://www.electroons.com/8051/electroons/matrix_keypad.html

https://saeedsolutions.blogspot.in/2012/06/interfacing-keypad-with-8051at89c51-c.html

 

[pplus]

The tutorial in assembler.
Interfacing hex keypad to 8051
You can use three keys for serial input password and a single key to confirm your entry, as this code does not handle simultaneous key press.

 

[embpic]

If you detect the key which is press then then take single bit to enable password function if this function is enable then when u will press any key put it any buffer like password[count] = key_press_number;
and increase the count after key press in password function.

 

[pplus]

/*------------------------------------------------
Keyboard 4*4 read
P1.7 ->-R3----------------F\|-E\|-D\|-C\|
P1.6 ->-R2----------------B\|-A\|-9\|-8\|
P1.5 ->-R1----------------7\|-6\|-5\|-4\|
P1.4 ->-R0----------------3\|-2\|-1\|-\0|
P1.3 -<-C3------------------|   |   |   |
P1.2 -<-C2----------------------|   |   |
P1.1 -<-C1--------------------------|   |
P1.0 -<-C0------------------------------|

keypressed = (1)	0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
                        0-Low                             15-High
Interrupt routine for 0 Low level needs.
------------------------------------------------*/
sfr P1 = 0x90;          /* SFR definition for Port 1 */
sfr P3 = 0xB0;          /* SFR definition for Port 3 */

#define  MASK  0x0F /*  low nibble mask 00001111 Setup P1 for Input P1.0-P1.3 Output P1.4-P1.7   */


/*------------------------------------------------
MAIN C Function
------------------------------------------------*/
void main (void)
{

unsigned int keypressed;     /* variable for key values */

	P1 = MASK;              	/* Setup P1 for Input P1.0-P1.3 Output P1.4-P1.7   */

/*--------------------------------------
Use the Toolbox buttons in the debugger
to change the value of P1.0-P1.3. 
--------------------------------------*/
while (1)
  {
		char row,runbit,pval; /* temp variable for port values */

 		for (row=0, runbit=0x10; row<4; row++) 
 		{
 			P1 = ~runbit|MASK;			   /*Output P1.4-P1.7  running 0 */
			pval = ~P1&MASK;           		   /* Read Input P1.0-P1.3 into pval -- 1 is pressed key*/
			keypressed = pval|keypressed<<4;  /* Pack pressed key in to keypressed */
 			runbit <<= 1;
		}
	}
}