Keypad.cpp

00001 #include "Keypad.h"
00002 #include "mbed.h"
00003 
00004 
00005 // Keypad layout:
00006 //                [row][col]   Col0 Col1 Col2 Col3 
00007 char const kpdLayout[4][4] = {{'1' ,'2' ,'3' ,'A'},  //row0
00008                               {'4' ,'5' ,'6' ,'B'},  //row1
00009                               {'7' ,'8' ,'9' ,'C'},  //row2
00010                               {'*' ,'0' ,'#' ,'D'}}; //row3
00011 
00012 //NIBBLE LOW=0000,  HIGH= 0111 1011 1101 1110    Col  (x)
00013 //const char KpdInMask[4] ={0xe0,0xd0,0xb0,0x70};
00014 const char KpdInMask[4] ={0x0e,0x0d,0x0b,0x07};
00015 
00016 //NIBBLE HIGH=1111,  LOW= 0111 1011 1101 1110    Rows (y)
00017 //const char KpdOutMask[4]={0xfe,0xfd,0xfb,0xf7};  
00018 const char KpdOutMask[4]={0x0e,0x0d,0x0b,0x07};
00019 
00020 
00021 Keypad::Keypad(PinName col1, PinName col2, PinName col3, PinName col4, PinName row1, PinName row2, PinName row3, PinName row4) : _cols(col1,col2,col3,col4), _rows(row1,row2,row3,row4) {   }
00022 
00023 char Keypad::ReadKey() {
00024     char KeyValue, Done=0;
00025     uint16_t y, x;
00026     
00027     //delay_ms(ContactBounceTime);  //warning no contact bounce protection
00028                                     //call read_key more than once with delay
00029                                     //between if key stay constant then key is pressed
00030     y = 0;
00031     while((y < 4) && (!Done))
00032     {
00033         _cols = KpdOutMask[y];              //write mask value to the column outputs     
00034         wait(0.01);  
00035 
00036         KeyValue = _rows;                   //read mask value from the row inputs
00037         
00038         if(KeyValue == KpdInMask[0])
00039             x = 0;
00040         else if(KeyValue == KpdInMask[1])
00041             x = 1;
00042         else if(KeyValue == KpdInMask[2])
00043             x = 2;
00044         else if(KeyValue == KpdInMask[3])
00045             x = 3;
00046         else
00047         {
00048             KeyValue='\0';                  //more than one key was pressed or no key in this row.
00049             x=9;          
00050         }
00051         if(x != 9)
00052         {
00053             Done = 1;                       //valid key found
00054             KeyValue = kpdLayout[x][y];     //convert to a character eg. '1','2','3','#','*'
00055         }
00056         y++;
00057     }
00058     return(KeyValue);
00059 }