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 #include "print.h"
   9
  10 // matrix is active low. (key on: 0/key off: 1)
  11 // row: Hi-Z(unselected)/low output(selected)
  12 //      PD:0,1,2,3,6,7/PC:6,7/PF:7
  13 // col: input w/pullup
  14 //      PB:0-8
  15
  16 // matrix state buffer
  17 uint8_t *matrix;
  18 uint8_t *matrix_prev;
  19 static uint8_t _matrix0[MATRIX_ROWS];
  20 static uint8_t _matrix1[MATRIX_ROWS];
  21
  22 static uint8_t read_col(void);
  23 static void unselect_rows(void);
  24 static void select_row(uint8_t row);
  25
  26
  27 // this must be called once before matrix_scan.
  28 void matrix_init(void)
  29 {
  30     // initialize row and col
  31     unselect_rows();
  32     DDRB = 0x00;
  33     PORTB = 0xFF;
  34
  35     // initialize matrix state: all keys off
  36     for (int i=0; i < MATRIX_ROWS; i++) _matrix0[i] = 0xFF;
  37     for (int i=0; i < MATRIX_ROWS; i++) _matrix1[i] = 0xFF;
  38     matrix = _matrix0;
  39     matrix_prev = _matrix1;
  40 }
  41
  42 uint8_t matrix_scan(void)
  43 {
  44     uint8_t row, state;
  45     uint8_t *tmp;
  46
  47     tmp = matrix_prev;
  48     matrix_prev = matrix;
  49     matrix = tmp;
  50
  51     for (row = 0; row < MATRIX_ROWS; row++) {
  52         select_row(row);
  53         _delay_us(30);  // without this wait read unstable value.
  54         state = read_col();
  55         unselect_rows();
  56
  57         matrix[row] = state;
  58     }
  59     return 1;
  60 }
  61
  62 bool matrix_is_modified(void) {
  63     for (int i=0; i <MATRIX_ROWS; i++) {
  64         if (matrix[i] != matrix_prev[i])
  65             return true;
  66     }
  67     return false;
  68 }
  69
  70 bool matrix_has_ghost(void) {
  71     for (int i=0; i <MATRIX_ROWS; i++) {
  72         if (matrix_has_ghost_in_row(i))
  73             return true;
  74     }
  75     return false;
  76 }
  77
  78 bool matrix_has_ghost_in_row(uint8_t row) {
  79     uint8_t state = ~matrix[row];
  80     // no ghost exists in case less than 2 keys on
  81     if (((state - 1) & state) == 0)
  82         return false;
  83
  84     // ghost exists in case same state as other row
  85     for (int i=0; i < MATRIX_ROWS; i++) {
  86         if (i == row) continue;
  87         if ((~matrix[i] & state) == state) return true;
  88     }
  89     return false;
  90 }
  91
  92 static uint8_t read_col(void)
  93 {
  94     return PINB;
  95 }
  96
  97 static void unselect_rows(void) {
  98     DDRD  = 0x00;
  99     PORTD = 0x00;
 100     DDRC  = 0x00;
 101     PORTC = 0x00;
 102     DDRF  = 0x00;
 103     PORTF = 0x00;
 104 }
 105
 106 static void select_row(uint8_t row)
 107 {
 108     switch (row) {
 109         case 0:
 110             DDRD  = (1<<0);
 111             PORTD = 0x00;
 112             DDRC  = 0x00;
 113             PORTC = 0x00;
 114             DDRF  = 0x00;
 115             PORTF = 0x00;
 116             break;
 117         case 1:
 118             DDRD  = (1<<1);
 119             PORTD = 0x00;
 120             DDRC  = 0x00;
 121             PORTC = 0x00;
 122             DDRF  = 0x00;
 123             PORTF = 0x00;
 124             break;
 125         case 2:
 126             DDRD  = (1<<2);
 127             PORTD = 0x00;
 128             DDRC  = 0x00;
 129             PORTC = 0x00;
 130             DDRF  = 0x00;
 131             PORTF = 0x00;
 132             break;
 133         case 3:
 134             DDRD  = (1<<3);
 135             PORTD = 0x00;
 136             DDRC  = 0x00;
 137             PORTC = 0x00;
 138             DDRF  = 0x00;
 139             PORTF = 0x00;
 140             break;
 141         case 4:
 142             DDRD  = (1<<6);
 143             PORTD = 0x00;
 144             DDRC  = 0x00;
 145             PORTC = 0x00;
 146             DDRF  = 0x00;
 147             PORTF = 0x00;
 148             break;
 149         case 5:
 150             DDRD  = (1<<7);
 151             PORTD = 0x00;
 152             DDRC  = 0x00;
 153             PORTC = 0x00;
 154             DDRF  = 0x00;
 155             PORTF = 0x00;
 156             break;
 157         case 6:
 158             DDRD  = 0x00;
 159             PORTD = 0x00;
 160             DDRC  = (1<<6);
 161             PORTC = 0x00;
 162             DDRF  = 0x00;
 163             PORTF = 0x00;
 164             break;
 165         case 7:
 166             DDRD  = 0x00;
 167             PORTD = 0x00;
 168             DDRC  = (1<<7);
 169             PORTC = 0x00;
 170             DDRF  = 0x00;
 171             PORTF = 0x00;
 172             break;
 173         case 8:
 174             DDRD  = 0x00;
 175             PORTD = 0x00;
 176             DDRC  = 0x00;
 177             PORTC = 0x00;
 178             DDRF  = (1<<7);
 179             PORTF = 0x00;
 180             break;
 181     }
 182 }