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Problem with 3x4 keypad

 
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ercarlitosg



Joined: 08 Sep 2014
Posts: 20

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Problem with 3x4 keypad
PostPosted: Fri Jun 26, 2015 7:48 pm     Reply with quote
Hello,

I am having trouble with a 3x4 keypad. I am using the flex_kbd driver inverted by me, because I am using pull down resistors instead of pull ups.

Here is the code of flex_kbd:

Code:

///////////////////////////////////////////////////////////////////////////
////                             Flex_KBD.C                            ////
////                  Generic keypad scan driver                       ////
////                                                                   ////
////  kbd_init()   Must be called before any other function.           ////
////                                                                   ////
////  c = kbd_getc(c)  Will return a key value if pressed or /0 if not ////
////                   This function should be called frequently so as ////
////                   not to miss a key press.                        ////
////                                                                   ////
///////////////////////////////////////////////////////////////////////////



//Keypad connection: 

#define COL0 PIN_A0
#define COL1 PIN_B1
#define COL2 PIN_B0
#define ROW0 PIN_A1
#define ROW1 PIN_A2
#define ROW2 PIN_A3
#define ROW3 PIN_A4

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

#define KBD_DEBOUNCE_FACTOR 33    // 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() {
}


short int ALL_ROWS (void)
{
   if (input (row0) & input (row1) & input (row2) & input (row3))
      return (1);
   else
      return (0);
}



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   : output_high(col0);
               output_low(col1);
               output_low(col2);
                    break;
         case 1   : output_low(col0);
               output_high(col1);
               output_low(col2);
                    break;
         case 2   : output_low(col0);
               output_low(col1);
               output_high(col2);
                    break;
       }

       if(kbd_down) {
         if(!ALL_ROWS()) {
           kbd_down=false;
           kchar=last_key;
           last_key='\0';
         }
       } else {
          if(ALL_ROWS()) {
             if(input (row0))
               row=0;
             else if(input (row1))
               row=1;
             else if(input (row2))
               row=2;
             else if(input (row3))
               row=3;
             last_key =KEYS[row][col];
             kbd_down = true;
          } else {
             ++col;
             if(col==3)
               col=0;
          }
       }
      kbd_call_count=0;
   }
  return(kchar);
}


I am always getting 0 when calling kbd_getc.
Thanks
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Fri Jun 26, 2015 9:01 pm     Reply with quote
Put 10K pullup resistors on all the row pins.

This circuit is what you need on each of the row pins:
Code:

               +5v
               |
               <
               > 10K       
               <         
               |
PIC pin -------o-------- Keypad row pin
   


If your PIC is running at +3.3v, then use that for the pullup voltage.
ercarlitosg



Joined: 08 Sep 2014
Posts: 20

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PostPosted: Sat Jun 27, 2015 4:31 am     Reply with quote
PCM programmer wrote:
Put 10K pullup resistors on all the row pins.

This circuit is what you need on each of the row pins:
Code:

               +5v
               |
               <
               > 10K       
               <         
               |
PIC pin -------o-------- Keypad row pin
   


If your PIC is running at +3.3v, then use that for the pullup voltage.


No I can't, instead of pull-up I must use pull down. I can't modify the board
temtronic



Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario

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PostPosted: Sat Jun 27, 2015 4:52 am     Reply with quote
Please post a 'link' to the KPD schematic or mfr/make/model....


Jay
ercarlitosg



Joined: 08 Sep 2014
Posts: 20

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PostPosted: Sun Jun 28, 2015 3:30 am     Reply with quote
temtronic wrote:
Please post a 'link' to the KPD schematic or mfr/make/model....


Jay


It's a standard black keypad. I don't have the model
Ttelmah



Joined: 11 Mar 2010
Posts: 19537

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PostPosted: Sun Jun 28, 2015 4:23 am     Reply with quote
The problem is that your 'premise' is wrong.

You are starting from the flexible driver, so (say):
Code:

short int ALL_ROWS (void)
{
   if (input (row0) & input (row1) & input (row2) & input (row3))
      return (0);
   else
      return (1);
}


and then reversing the 'output' of this:
Code:

short int ALL_ROWS (void)
{
   if (input (row0) & input (row1) & input (row2) & input (row3))
      return (1);
   else
      return (0);
}


This is not what you have to do, to work with the signals using the other polarity.
You need to reverse the _input_ of the tests. So (for instance):
Code:

short int ALL_ROWS (void)
{
   if (!input (row0)) & (!input (row1)) & (!input (row2)) & (!input (row3)))
      return (1);
   else
      return (0);
}

Note the negation of the inputs.
It is your input levels that have changed, not the logic of the tests.....

You need to re-think how the driver works, and reverse every actual output signal, and the input tests.

Last edited by Ttelmah on Sun Jun 28, 2015 9:29 am; edited 1 time in total
temtronic



Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario

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PostPosted: Sun Jun 28, 2015 4:51 am     Reply with quote
re: ...It's a standard black keypad..

Hopefully you've 'rung out' AKA decoded which pins do what function. There is NO 'standard' for keyboards. I have 4 'standard black keyboards' in a drawer here ALL have different matrices for the 3x4 layout ! One is actually a 2x6 layout, arrgh !!

So please don't get caught by the 'standard black keyboard' idea. Same holds true for 2x16 LCD modules.....


Jay
ercarlitosg



Joined: 08 Sep 2014
Posts: 20

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PostPosted: Tue Jun 30, 2015 6:48 am     Reply with quote
temtronic wrote:
re: ...It's a standard black keypad..

Hopefully you've 'rung out' AKA decoded which pins do what function. There is NO 'standard' for keyboards. I have 4 'standard black keyboards' in a drawer here ALL have different matrices for the 3x4 layout ! One is actually a 2x6 layout, arrgh !!

So please don't get caught by the 'standard black keyboard' idea. Same holds true for 2x16 LCD modules.....


Jay


OK, thanks I am almost new to electronics dveloping.
ercarlitosg



Joined: 08 Sep 2014
Posts: 20

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PostPosted: Tue Jun 30, 2015 7:16 am     Reply with quote
Ttelmah wrote:
The problem is that your 'premise' is wrong.

You are starting from the flexible driver, so (say):
Code:

short int ALL_ROWS (void)
{
   if (input (row0) & input (row1) & input (row2) & input (row3))
      return (0);
   else
      return (1);
}


and then reversing the 'output' of this:
Code:

short int ALL_ROWS (void)
{
   if (input (row0) & input (row1) & input (row2) & input (row3))
      return (1);
   else
      return (0);
}


This is not what you have to do, to work with the signals using the other polarity.
You need to reverse the _input_ of the tests. So (for instance):
Code:

short int ALL_ROWS (void)
{
   if (!input (row0)) & (!input (row1)) & (!input (row2)) & (!input (row3)))
      return (1);
   else
      return (0);
}

Note the negation of the inputs.
It is your input levels that have changed, not the logic of the tests.....

You need to re-think how the driver works, and reverse every actual output signal, and the input tests.


Thanks for your tip. I tought inverting the function return value would work, but no.

Finally solved, you wouldn't expect what happened. Some days ago, I moved the project to my bitbucket git repository. No problem, all fine, except that the ccs ide was opening the flex_kbd.c from the old location Embarassed Embarassed Embarassed so any modification I did was to the old file, not to the new file in the git repository.

Also, here I post the code if anyone wants the flex_kbd driver for pull down resistors

Code:

///////////////////////////////////////////////////////////////////////////
////                             Flex_KBD.C                            ////
////                  Generic keypad scan driver                       ////
////                                                                   ////
////  kbd_init()   Must be called before any other function.           ////
////                                                                   ////
////  c = kbd_getc(c)  Will return a key value if pressed or /0 if not ////
////                   This function should be called frequently so as ////
////                   not to miss a key press.                        ////
////                                                                   ////
///////////////////////////////////////////////////////////////////////////

static uint8_t kbd_call_count;
static short int kbd_down;
static char last_key;
static uint8_t col;


//Keypad connection: 

#define COL0 PIN_A0
#define COL1 PIN_B1
#define COL2 PIN_B0
#define ROW0 PIN_A4
#define ROW1 PIN_A3
#define ROW2 PIN_A2
#define ROW3 PIN_A1

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

#define KBD_DEBOUNCE_FACTOR 33    // 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() {
}


short int ALL_ROWS (void)
{
   if (!input (row0) & !input (row1) & !input (row2) & !input (row3))
      return (0);
   else
      return (1);
}



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   : output_high(col0);
               output_low(col1);
               output_low(col2);
                    break;
         case 1   : output_low(col0);
               output_high(col1);
               output_low(col2);
                    break;
         case 2   : output_low(col0);
               output_low(col1);
               output_high(col2);
                    break;
       }

       if(kbd_down) {
         if(!ALL_ROWS()) {
           kbd_down=false;
           kchar=last_key;
           last_key='\0';
         }
       } else {
          if(ALL_ROWS()) {
             if(input (row0)) {
               row=0;
               puts("ROW 0");
             } else if(input (row1)) {
               row=1;
               puts("ROW 1");
             } else if(input (row2)) {
               row=2;
               puts("ROW 2");
             } else if(input (row3)) {
               row=3;
               puts("ROW 3");
             }
             
             last_key =KEYS[row][col];
             kbd_down = true;
          } else {
             ++col;
             if(col==3)
               col=0;
          }
       }
      kbd_call_count=0;
   }
  return(kchar);
}

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