Re: Help with Keypad 4x4 using RCM5600W

@Scott, Thank you for your suggestion.

I change like this, but there are still errors. When the data input at writeVal is 0xFE, result of readVal = 0xFF, when I don't perform keystrokes.

What pull-up resistors too small for source 3.3v, I used 4k7 ?


for(rowScan=0; rowScan<4; rowScan++){

   //writeVal = ~(unsigned char)pow2(rowScan);
   writeVal = ~(unsigned char)(1<<rowScan);

   //WrPortI(PBDDR, &PBDDRShadow, writeVal);
   WrPortI(PBDR, &PBDRShadow, writeVal);

   readVal = RdPortI(PBDR);
   if(readVal != writeVal) break;
}


Thank You
DC

--- In [email protected], Scott Henion <shenion@...> wrote:
>
> On 8/20/2012 1:10 PM, dynamic_c@... wrote:
> > Hello,
> >
> > I created a program to read a 4x4 keypad, but the output always 0xFF which means
> > there is no button is pressed. Where is my fault location under this program?
> >
> > // all outputs add pull up to 3.3v with 4k7 resistor
> > // all inputs add series resistors 1k
> > //
> > // Keypad 4x4 with inputs (PB0-3) and outputs (PB4-7)
> > ////////////////////////////////////////////
> > //                      <-- INPUTS
> > //  1   2   3    Clear  <-- PB0
> > //  4   5   6    Up     <-- PB1
> > //  7   8   9    Down   <-- PB2
> > // Menu 0 Cancel Enter  <-- PB3
> > ///////////////////////////////////////////
> > // PB4 PB5 PB6 PB7      OUTPUTS
> >
> > #use "rcm56xxw.lib"
> >
> > unsigned char getKey(){
> >   unsigned char rowScan, readVal, writeVal, d;
> >   for(rowScan=0; rowScan<4; rowScan++){
> >     writeVal = ~(unsigned char)pow2(rowScan);
> >     WrPortI(PBDDR, &PBDDRShadow, writeVal);
> >     readVal = RdPortI(PBDDR);
> >     if(readVal != writeVal) break; // if button pressed, exit for
> >   }
> >   
> >   switch(readVal){
> >
> >     // scan row 1 // OUTPUTS <-- INPUTS
> >     case 0xEE:    // 1110 1110 <-- 1111 1110
> >       return 1;
> >     case 0xDE:    // 1101 1110 <-- 1111 1110
> >       return 2;
> >     case 0xBE:    // 1011 1110 <-- 1111 1110
> >       return 3;
> >     case 0x7E:    // 0111 1110 <-- 1111 1110 clear button
> >       return 0x0A;
> >
> >     // scan row 2
> >     case 0xED:    // 1110 1101 <-- 1111 1101
> >       return 4;
> >     case 0xDD:    // 1101 1101 <-- 1111 1101
> >       return 5;
> >     case 0xBD:    // 1011 1101 <-- 1111 1101
> >       return 6;
> >     case 0x7D:    // 0111 1101 <-- 1111 1101 up button
> >       return 0x0B;
> >
> >     // scan row 3
> >     case 0xEB:    // 1110 1011 <-- 1111 1011
> >       return 7;
> >     case 0xDB:    // 1101 1011 <-- 1111 1011
> >       return 8;
> >     case 0xBB:    // 1011 1011 <-- 1111 1011
> >       return 9;
> >     case 0x7B:    // 0111 1011 <-- 1111 1011 down button
> >       return 0x0C;
> >
> >     // scan row 4
> >     case 0xE7:    // 1110 0111 <-- 1111 0111 menu button
> >       return 0x0E;
> >     case 0xD7:    // 1101 0111 <-- 1111 0111
> >       return 0;
> >     case 0xB7:    // 1011 0111 <-- 1111 0111 cancel button
> >       return 0x0F;
> >     case 0x77:    // 0111 0111 <-- 1111 0111 enter button
> >       return 0x0D;
> >
> >     default:
> >       return 0xFF; // no button is pressed
> >   }
> > }
> >
> > void main(){
> >   brdInit();
> >
> >   WrPortI(PBDDR, &PBDDRShadow, 0xFF);
> >
> >   for(;;){
> >     costate{
> >       printf("%02X ", getKey());
> >     }
> >   }
> > }
> >
> 
> You are writing to the port B direction register and trying to read it
> back. You never wrote anything to the data reg.
> 
> The direction register PBDDR may be write only (it is on earlier CPUs.)
> 
> One comment about this:
> 
>    writeVal = ~(unsigned char)pow2(rowScan);
> 
> 
> pow2() is a higher math function, takes considerable overhead in the
> function and then also converting float to integer.
> 
> This is much simpler:
> 
>    writeVal = ~(unsigned char)(1<<rowScan);
> 
> 
> <Scott>
> 
> -- 
> ------------------------------------------
>      Scott G. Henion, Consultant
> Web site:    http://SHDesigns.org
> ------------------------------------------
>