matrix.c

   1 /*
   2  * scan matrix
   3  */
   4 #include <avr/io.h>
   5 #include <util/delay.h>
   6 #include "keymap.h"
   7 #include "matrix.h"
   8
   9 // matrix is active low. (key on: 0/key off: 1)
  10 // row: Hi-Z(unselected)/low output(selected)
  11 //      PD:0,1,2,3,6,7/PC:6,7/PF:7
  12 // col: input w/pullup
  13 //      PB:0-8
  14
  15 // matrix state buffer
  16 uint8_t *matrix;
  17 uint8_t *matrix_prev;
  18 static uint8_t _matrix0[MATRIX_ROWS];
  19 static uint8_t _matrix1[MATRIX_ROWS];
  20
  21 static uint8_t read_col(void);
  22 static void unselect_rows(void);
  23 static void select_row(uint8_t row);
  24
  25
  26 // this must be called once before matrix_scan.
  27 void matrix_init(void)
  28 {
  29     // initialize row and col
  30     unselect_rows();
  31     DDRB = 0x00;
  32     PORTB = 0xFF;
  33
  34     // initialize matrix state: all keys off
  35     for (int i=0; i < MATRIX_ROWS; i++) _matrix0[i] = 0xFF;
  36     for (int i=0; i < MATRIX_ROWS; i++) _matrix1[i] = 0xFF;
  37     matrix = _matrix0;
  38     matrix_prev = _matrix1;
  39 }
  40
  41 uint8_t matrix_scan(void)
  42 {
  43     uint8_t row, state;
  44     uint8_t *tmp;
  45
  46     tmp = matrix_prev;
  47     matrix_prev = matrix;
  48     matrix = tmp;
  49
  50     for (row = 0; row < MATRIX_ROWS; row++) {
  51         select_row(row);
  52         _delay_us(30);  // without this wait read unstable value.
  53         state = read_col();
  54         unselect_rows();
  55
  56         matrix[row] = state;
  57     }
  58     return 1;
  59 }
  60
  61 bool matrix_is_modified(void) {
  62     for (int i=0; i <MATRIX_ROWS; i++) {
  63         if (matrix[i] != matrix_prev[i])
  64             return true;
  65     }
  66     return false;
  67 }
  68
  69 bool matrix_has_ghost(void) {
  70     for (int i=0; i <MATRIX_ROWS; i++) {
  71         if (matrix_has_ghost_in_row(i))
  72             return true;
  73     }
  74     return false;
  75 }
  76
  77 bool matrix_has_ghost_in_row(uint8_t row) {
  78     uint8_t state = ~matrix[row];
  79     // no ghost exists in case less than 2 keys on
  80     if (((state - 1) & state) == 0)
  81         return false;
  82
  83     // ghost exists in case same state as other row
  84     for (int i=0; i < MATRIX_ROWS; i++) {
  85         if (i == row) continue;
  86         if ((~matrix[i] & state) == state) return true;
  87     }
  88     return false;
  89 }
  90
  91 static uint8_t read_col(void)
  92 {
  93     return PINB;
  94 }
  95
  96 static void unselect_rows(void) {
  97     DDRD  = 0x00;
  98     PORTD = 0x00;
  99     DDRC  = 0x00;
 100     PORTC = 0x00;
 101     DDRF  = 0x00;
 102     PORTF = 0x00;
 103 }
 104
 105 static void select_row(uint8_t row)
 106 {
 107     switch (row) {
 108         case 0:
 109             DDRD  = (1<<0);
 110             PORTD = 0x00;
 111             DDRC  = 0x00;
 112             PORTC = 0x00;
 113             DDRF  = 0x00;
 114             PORTF = 0x00;
 115             break;
 116         case 1:
 117             DDRD  = (1<<1);
 118             PORTD = 0x00;
 119             DDRC  = 0x00;
 120             PORTC = 0x00;
 121             DDRF  = 0x00;
 122             PORTF = 0x00;
 123             break;
 124         case 2:
 125             DDRD  = (1<<2);
 126             PORTD = 0x00;
 127             DDRC  = 0x00;
 128             PORTC = 0x00;
 129             DDRF  = 0x00;
 130             PORTF = 0x00;
 131             break;
 132         case 3:
 133             DDRD  = (1<<3);
 134             PORTD = 0x00;
 135             DDRC  = 0x00;
 136             PORTC = 0x00;
 137             DDRF  = 0x00;
 138             PORTF = 0x00;
 139             break;
 140         case 4:
 141             DDRD  = (1<<6);
 142             PORTD = 0x00;
 143             DDRC  = 0x00;
 144             PORTC = 0x00;
 145             DDRF  = 0x00;
 146             PORTF = 0x00;
 147             break;
 148         case 5:
 149             DDRD  = (1<<7);
 150             PORTD = 0x00;
 151             DDRC  = 0x00;
 152             PORTC = 0x00;
 153             DDRF  = 0x00;
 154             PORTF = 0x00;
 155             break;
 156         case 6:
 157             DDRD  = 0x00;
 158             PORTD = 0x00;
 159             DDRC  = (1<<6);
 160             PORTC = 0x00;
 161             DDRF  = 0x00;
 162             PORTF = 0x00;
 163             break;
 164         case 7:
 165             DDRD  = 0x00;
 166             PORTD = 0x00;
 167             DDRC  = (1<<7);
 168             PORTC = 0x00;
 169             DDRF  = 0x00;
 170             PORTF = 0x00;
 171             break;
 172         case 8:
 173             DDRD  = 0x00;
 174             PORTD = 0x00;
 175             DDRC  = 0x00;
 176             PORTC = 0x00;
 177             DDRF  = (1<<7);
 178             PORTF = 0x00;
 179             break;
 180     }
 181 }