KBD.C   Generic keypad scan driver /////////////////////////////////////////////////////////////////////////// //// 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. //// //// //// //// (C) Copyright 1996,1997 Custom Computer Services //// //// //// /////////////////////////////////////////////////////////////////////////// ////////////////// The following defines the keypad layout on port B #byte kbd = 6 // Keypad is connected to port B (address 6) //Keypad connection: (for example column 0 is B2) // Bx: #ifdef blue_keypad ///////////////////////////////////// For the blue keypad #define COL0 (1 << 2) #define COL1 (1 << 3) #define COL2 (1 << 6) #define ROW0 (1 << 4) #define ROW1 (1 << 7) #define ROW2 (1 << 1) #define ROW3 (1 << 5) #else ////////////////////////////////////////////////// For my keypad #define COL0 (1 << 6) #define COL1 (1 << 2) #define COL2 (1 << 3) #define ROW0 (1 << 4) #define ROW1 (1 << 5) #define ROW2 (1 << 1) #define ROW3 (1 << 7) #endif #define ALL_ROWS (ROW0|ROW1|ROW2|ROW3) #define ALL_PINS (ALL_ROWS|COL0|COL1|COL2) // 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() { #ifdef __PCM__ port_b_pullups(true); // If not PCM be sure to use external pullups #endif } 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_b(ALL_PINS&~COL0); kbd=~COL0&ALL_PINS; break; case 1 : set_tris_b(ALL_PINS&~COL1); kbd=~COL1&ALL_PINS; break; case 2 : set_tris_b(ALL_PINS&~COL2); kbd=~COL2&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==3) col=0; } } kbd_call_count=0; } set_tris_b(ALL_PINS); return(kchar); }

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