1 | /* Amiga Keyboard reading on Atmel AVR
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2 | * Copyright 2010, Adrien Destugues <pulkomandy@pulkomandy.ath.cx>
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3 | * Distributed under the terms of the MIT Licence */
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4 |
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5 | #include <avr/io.h>
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6 | #include <avr/interrupt.h>
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7 | #include <avr/pgmspace.h>
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8 | #include <util/delay.h>
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9 |
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10 | #include "amiga_keyboard.h"
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11 | // #include "keymap.h"
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12 |
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13 |
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14 | //PIN configuration
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15 | #define AK_CLK PD3 /* Also INT1 */
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16 | #define AK_PORT PIND
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17 | #define AK_DATA PD4
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18 |
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19 | volatile uint8_t kbd_data;
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20 | volatile uint8_t char_waiting;
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21 | uint8_t started;
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22 | uint8_t bit_count;
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23 | uint8_t shift;
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24 |
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25 |
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26 | // Notify the keyboard we got the last char right
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27 | static inline void acknowledge_char()
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28 | {
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29 | // We have to pull down the "DATA" line
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30 |
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31 | // Set it as an input
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32 | DDRD |= (1<<AK_DATA);
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33 |
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34 | // Down for 85 us
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35 | PORTD &= ~(1<<AK_DATA);
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36 | _delay_us(85);
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37 |
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38 | // Up again to let the keybord talk
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39 | PORTD |= (1<<AK_DATA);
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40 |
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41 | // And it's now an input again
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42 | DDRD &= ~(1<<AK_DATA);
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43 | }
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44 |
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45 |
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46 | // Interrupt vector - Triggered when there is activity on the clock line
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47 | ISR(INT1_vect)
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48 | {
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49 | static char tmp_kdata;
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50 | //make sure clock line is low, if not ignore this transition
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51 | if(AK_PORT & (1<<AK_CLK)){
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52 | return;
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53 | }
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54 |
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55 | // First bit, reset everything then continue below
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56 | if(!started){
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57 | started = 1;
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58 | bit_count = 0;
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59 | tmp_kdata = 0;
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60 | }
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61 |
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62 | if(bit_count < 8) { //we started, read in the new bit
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63 | //put a 1 in the right place of kdb_data if PC2 is high, leave
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64 | //a 0 otherwise
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65 | if(!(AK_PORT & (1<<AK_DATA))) tmp_kdata |= (128>>bit_count);
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66 | bit_count++;
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67 | }
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68 |
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69 | if(bit_count >= 8)
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70 | { // enough bits
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71 | started = 0;
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72 | bit_count = 0;
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73 |
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74 | /*
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75 | if(kbd_data == 0xF0){ //release code
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76 | release = 1;
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77 | kbd_data = 0;
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78 | return;
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79 | } else if (kbd_data == 0x12) { //hanlde shift key
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80 | if(release == 0){
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81 | shift = 1;
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82 | } else {
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83 | shift = 0;
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84 | release = 0;
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85 | }
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86 | return;
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87 | } else { //not a special character
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88 | if(release){ //we were in release mode - exit release mode
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89 | release = 0;
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90 | //ignore that character
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91 | } else {
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92 | char_waiting = 1;
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93 | }
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94 | }*/
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95 | kbd_data = tmp_kdata;
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96 | char_waiting=1;
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97 | }
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98 | }
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99 |
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100 |
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101 | /*
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102 | char ak_scancode_to_ascii(uint8_t data){
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103 | char to_ret = pgm_read_byte(&(keymap[data])); //grab character from array
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104 | if(shift) to_ret -= 0x20;
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105 | return to_ret;
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106 | }
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107 | */
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108 |
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109 | uint8_t ak_wait_scancode(){
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110 | while(!char_waiting);
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111 | return ak_read_scancode();
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112 | }
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113 |
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114 |
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115 | uint8_t ak_read_scancode() {
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116 | while ((AK_PORT & (1<<AK_CLK)) == 0);
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117 | _delay_us(30);
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118 | acknowledge_char();
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119 |
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120 | char_waiting = 0;
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121 | return kbd_data;
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122 | }
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123 |
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124 |
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125 | void ak_init_keyboard(){
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126 | started = 0;
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127 | kbd_data = 0;
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128 | bit_count = 0;
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129 |
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130 | //make AK_CLK input pin
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131 | DDRD &= ~(1<<AK_CLK);
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132 | //turn on pullup resistor
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133 | AK_PORT |= (1<<AK_CLK);
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134 |
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135 | // Interrupt configuration
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136 | // We use INT1 falling edge
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137 | MCUCR |= (1<<ISC11);
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138 | MCUCR &= ~(1<<ISC10);
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139 |
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140 | // Enable INT1
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141 | GIMSK |= (1<<INT1);
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142 |
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143 | // Enable interrupts
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144 | sei();
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145 |
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146 | acknowledge_char();
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147 | }
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148 |
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149 |
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