velleman 16 keys keyboard - matrix type 4x4

[Cloud]

I have a this keypad and managed to get the keyboard working with the following codes, however I am not able to get the 4th column. ie A,B,C,D

Hope someone can help


#byte kbd = 0xF81 // This puts the entire structure


#define set_tris_kbd(x) set_tris_b(x)



//Keypad connection: (for example column 0 is B2)
// Bx:


#define COL0 (1 << 0) //1
#define COL1 (1 << 1) //10
#define COL2 (1 << 2) //100
#define COL3 (1 << 3) //1000

#define ROW0 (1 << 4) //10000
#define ROW1 (1 << 5) //100000
#define ROW2 (1 << 6) //1000000
#define ROW3 (1 << 7) //10000000

// The following bitmasks are the same as the above,

// but written in a different format.




#define ALL_ROWS (ROW0|ROW1|ROW2|ROW3)
#define ALL_PINS (ALL_ROWS|COL0|COL1|COL2|COL3)

// Keypad layout:
char const KEYS[4][4] = {{'1','2','3','A'},
{'4','5','6','B'},
{'7','8','9','C'},
{'*','0','#','D'}};

#define KBD_DEBOUNCE_FACTOR 22 // Set this number to apx n/333 where
// n is the number of times you expect
// to call kbd_getc each second


void kbd_init() {
port_b_pullups(true);
}

char kbd_getc() {
static BYTE kbd_call_count;
static short int kbd_down;
static char last_key;
static BYTE col;

BYTE kchar;
BYTE row;

kchar='\0';
if(++kbd_call_count>KBD_DEBOUNCE_FACTOR) {
switch (col) {
case 0 : set_tris_kbd(ALL_PINS&~COL0);
kbd=~COL0&ALL_PINS;
break;
case 1 : set_tris_kbd(ALL_PINS&~COL1);
kbd=~COL1&ALL_PINS;
break;
case 2 : set_tris_kbd(ALL_PINS&~COL2);
kbd=~COL2&ALL_PINS;
break;
case 3 : set_tris_kbd(ALL_PINS&~COL3);
kbd=~COL3&ALL_PINS;
break;
}

if(kbd_down) {
if((kbd & (ALL_ROWS))==(ALL_ROWS)) {
kbd_down=FALSE;
kchar=last_key;
last_key='\0';
}
} else {
if((kbd & (ALL_ROWS))!=(ALL_ROWS)) {
if((kbd & ROW0)==0)
row=0;
else if((kbd & ROW1)==0)
row=1;
else if((kbd & ROW2)==0)
row=2;
else if((kbd & ROW3)==0)
row=3;
last_key =KEYS[row][col];
kbd_down = TRUE;
} else {
++col;
if(col==4)
col=0;
}
}
kbd_call_count=0;
}
set_tris_kbd(ALL_PINS);
return(kchar);
}

[Guest]

Have you checked with an oscilloscope or meter that the corresponding row goes low on this column when key pressed? The column may not be connected.

[Cloud]

You are right.

Thanks. The code is okay.

[Guest]

I´ve tried to use this code with the ex_lcdkb.c included with the compiler, and it doesn´t work. I´ve changed the portb_pullups as I thought it could be the reason, but still doesn´t work. The LCD displays Ready... all the time!.

I´m using a 16f877 at 4Mhz, the lcd in port D and a 4x4 keypad on port B, know why can this be?

Thanx.