[ts-7000] Re: TS-7200 4x4 keypad qeustion

["bfbay2005" <>]

Here is a version of keypad that I hacked up.. Hopefully it will help.

Brian


/* 
 * This code is a severely hacked version of the keypad demo.  
 * I don't suggest that you adapt to your needs.    
 *
 * The debouncing may or may not be done properly..I'm leaning towards no.
 *
 */

#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <stdio.h>
#include <fcntl.h>
        
#define GPIO 0x80840000                                         // General 
Purpose I/O Base Address
#define PBDR (0x04/sizeof(unsigned int))        // Port B Data Register
#define PBDDR (0x14/sizeof(unsigned int))       // Port B Directection Register

unsigned int getkeys();
void printkey(unsigned int);

volatile unsigned int *gpio;
volatile unsigned int *pbdr;
volatile unsigned int *pbddr;


// Key Mappings 
struct key {
        unsigned int hex_key;
        unsigned char char_key;
} keys[] = {
                0xee,'1', 0xde,'2', 0xbe,'3', 0x7e,'A',
                0xed,'4', 0xdd,'5', 0xbd,'6', 0x7d,'B',
                0xeb,'7', 0xdb,'8', 0xbb,'9', 0x7b,'C',
                0xe7,'*', 0xd7,'0', 0xb7,'?', 0x77,'D'
};



int main()
{
        unsigned int key = 0,pressed = 0;       
    
        int fd = open("/dev/mem", O_RDWR|O_SYNC);
        gpio = mmap(0,getpagesize(),PROT_READ|PROT_WRITE,MAP_SHARED,fd,GPIO);

        // set pointers to register addresses
        pbdr = &gpio[PBDR];
        pbddr = &gpio[PBDDR];
        
        // set port b register to output
        *pbddr = 0xf;
        
        for(;;){
                unsigned int changed;
                
                key = getkeys();

                // xor 
                changed = pressed ^ key;
                
                if(changed){
                        printkey(key);
                        pressed = key;
                }
        
                usleep(1000000/30);
        }
        
        close(fd);
        return 0;
}

unsigned int getkeys(){
        unsigned int pos, on = 0;

        for(pos=0;pos < 4;pos++ ){
                // left shift by pos then flip bits ( 1's comp)
                *pbdr =  ~(1 << pos);

                // if true
                if((*pbdr >> 4) ^ 0xf){
                   on =  *pbdr;
                   return on;
                }
        }

        // nothing pressed
        return 0;
}


void printkey(unsigned int key){
        int i;
        
    for(i=0;i<sizeof(keys)/sizeof(keys[0]);i++){
                
                if(key == keys[i].hex_key){
                        printf("%c\n",keys[i].char_key);
                }
        }
}










--- In  "ticrus00" <> wrote:
>
> Jason, thank you I think I am half way there.  My failure to
> understand how the keypad seems to be my problem. 
> 
> I have a few more questions.  If it is setting 1 bit in *dat, why the
> need to invert?  Is 1 treated as low voltage and 0 as a large voltage?
>  I noticed it is setting a bit in the far right nibble.  If A,B,C,D
> are set in that nibble, is 1,2,3,4 the left nibble? If so, am I right
> in saying that if you change bits in the first nibble for A,B,C, or D,
> then the left nibble will change? Also what happens if 2 or more lines
> are selected, such as A and B at the same time?  Could you explain the
> second line, 'on |= (~(*dat >> 4) & 0xf) << (4 * pos);'?  I appreciate
> the time you have taken to help me out.
> 
> Justin
> --- In  Jason Stahls <jason@> wrote:
> >
> > The 4x4 keypad works like this
> > 
> >    ABC D
> > 1 + + + +
> > 2 + + + +
> > 3 + + + +
> > 4 + + + +
> > 
> > Where you apply power to A, then check for that voltage on 1, 2,
3, and 
> > 4.  You then apply power to B and check 1, 2, 3, and 4 again, and so
> on. 
> > 
> > *dat = ~(1 << pos);
> > 
> > This line is setting a bit in dat, if we break all of it down it
looks 
> > like this (I think, I still much up bitwise some days)
> > 
> > 1 << pos, this bit shifts 1 to the left pos positions.  So, in binary 
> > (I'm going to pad this to nibble size) if we shift 0001 left 2
> places we 
> > get 0100, 1 is 0010, ect. 
> > 
> > ~(1 << pos), we then invert the result from (1 << pos), so if we had 
> > 0010 and inverted it with ~ we'd get 1101
> > 
> > Hope that helps.
> > 
> > Jason
> > 
> > ticrus00 wrote:
> > > Forgive me I am new at this.  I am trying to understand whats
going on
> > > in the keypad.c sample code provided with the ts-7200 board.  
> > > Specifically:
> > >
> > > unsigned int get_keys(void) {
> > >   unsigned int pos, on = 0;
> > >
> > >   for(pos = 0; pos < 4; pos++) {
> > >           *dat = ~(1 << pos); <- I DON'T UNDERSTAND THIS
> > >           on |= (~(*dat >> 4) & 0xf) << (4 * pos);
> > >   }
> > >   return on;
> > > }
> > >
> > > The above arrow is the line I am not following because to me its is
> > > setting *dat equal to  ~(1 << pos).  But when *dat is used in
the line
> > > below it is a different value.  I don't know anything about the
keypad
> > > and maybe thats my problem.  Is it some sort of msg to the
keypad?  Is
> > > there any documentation out there besides the keypad.c and the
> > > hardware guide that came with the board?  
> > >
> > >
> > >
> > >
> > >
> > >  
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> >
>




 
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