1 | #ifndef F_CPU
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2 | #define F_CPU 16000000UL
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3 | #endif
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4 | ////////////////////////////////////////////////////////////////////////////////////////////
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5 | #include <avr/io.h>
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6 | #include <util/delay.h>
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7 | ////////////////////////////////////////////////////////////////////////////////////////////
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8 | #define I2C_DDR DDRD // Register für die I2C Kommunikation
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9 | #define I2C_DDR_REG_BIT DDD5 //
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10 | #define I2C_PORT PORTD // I2C Port definition
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11 |
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12 | #define SCL PD4 // Port D
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13 | #define SDA PD5 // Port D
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14 |
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15 | #define SDA_LESE_PIN PIND
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16 | #define SDA_LESE_BIT SDA
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17 | ////////////////////////////////////////////////////////////////////////////////////////////
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18 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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19 | void sda_low()
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20 | {
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21 | I2C_PORT &= ~(1<<SDA); // internen Pull-Up aus
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22 | I2C_DDR |= (1<<I2C_DDR_REG_BIT); // Pin von SDA als Ausgang
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23 |
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24 | }
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25 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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26 | void sda_high()
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27 | {
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28 | I2C_DDR &= ~(1<<I2C_DDR_REG_BIT); // Pin von SDA als Eingang
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29 | I2C_PORT |= (1<<SDA); // internen Pull-Up an
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30 | }
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31 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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32 | ////////////////////////////////////////////////////////////////////////////////////////////
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33 |
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34 | #define I2C_SCL_LOW I2C_PORT &= ~(1 << SCL) // Clock Low Output
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35 | #define I2C_SCL_HIGH I2C_PORT |= (1 << SCL) // Clock High Output
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36 |
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37 | #define I2C_SDA_LOW sda_low() // Daten Leitung Low
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38 | #define I2C_SDA_HIGH sda_high() // Data Wire High
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39 |
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40 | #define ACK 0 // Ack empfangen
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41 | #define NACK 1 // Ack nicht empfangen
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42 |
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43 | //#define S_DELAY _delay_loop_1(1); // ca. 2.76µs H-Time Begrenzt auf 262.14 ms / F_CPU in MHz
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44 | #define M_DELAY _delay_us(1); // Begrenzt auf 768us/F_CPU in MHz also bei 16MHz 48us / 8MHz 96us
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45 | //#define DELAY _delay_ms(1); // Begrenzt auf 262.14 ms/F_CPU in MHz also bei 16MHz 16,38ms / 8MHz 32,7675ms
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46 | #define S_DELAY _delay_loop_1((F_CPU * 0.000001) / 3) /**< 1 us delay */
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47 | //#define wait1ms _delay_loop_2((F_CPU * 0.001) / 4) /**< 1 ms delay */
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48 |
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49 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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50 | unsigned char i2c_try_scl(unsigned char start_trials)
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51 | {
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52 | // 10 Mal kurz warten, wenn SCL auf LOW gehalten wird
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53 | while((!SCL) && (start_trials <50))
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54 | {
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55 | start_trials++;
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56 | S_DELAY;
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57 | }
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58 | if(!SCL) return 0 ; return 1;
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59 | }
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60 |
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61 | void i2c_master_stop(void);
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62 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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63 |
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64 | ////////////////////////////////////////////////////////////////////////////////////////////
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65 | // I2C-Master Interface Standard Routinen
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66 | ////////////////////////////////////////////////////////////////////////////////////////////
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67 | void i2c_master_init(void)
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68 | {
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69 | I2C_DDR |= (1<<SCL); // SCL Leitung als Ausgang definieren
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70 | S_DELAY;
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71 | I2C_SCL_HIGH; // Cockleitung auf H setzen
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72 | I2C_SDA_HIGH; // Datenleitung auf H setzen
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73 | S_DELAY; // kurz warten
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74 | i2c_master_stop();
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75 | }
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76 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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77 | void i2c_master_clk_toggle(void)
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78 | {
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79 | i2c_try_scl(0x0A);
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80 |
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81 | I2C_SCL_HIGH;
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82 | S_DELAY;
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83 | S_DELAY;
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84 | I2C_SCL_LOW;
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85 | S_DELAY;
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86 | }
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87 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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88 | void i2c_master_start(void)
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89 | {
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90 | // Übergang von H->L auf SDA, wobei SCL H ist.
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91 | i2c_try_scl(0x0A);
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92 |
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93 | I2C_SDA_HIGH; // SDA vorsichtshalber auf HIGH ziehen
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94 | // S_DELAY;
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95 | I2C_SCL_HIGH; // SCL auf High
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96 | S_DELAY;
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97 | I2C_SDA_LOW; // SDA auf Low ziehen
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98 | M_DELAY;
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99 | M_DELAY;
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100 | M_DELAY;
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101 | I2C_SCL_LOW; // SCL auf low
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102 | S_DELAY;
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103 | }
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104 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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105 | void i2c_master_stop(void)
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106 | {
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107 | // Übergang von L->H auf SDA, wobei SCL H ist.
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108 | i2c_try_scl(0x0A);
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109 | S_DELAY;
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110 | I2C_SDA_LOW; // SDA vorsichtshalber auf LOW ziehen
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111 | S_DELAY; // Kurz abwarten
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112 | I2C_SCL_HIGH; // SCL auf High setzen
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113 | S_DELAY;
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114 | I2C_SDA_HIGH; // SDA von L auf H ziehen
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115 | S_DELAY;
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116 | }
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117 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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118 | unsigned char i2c_master_write(unsigned char b)
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119 | {
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120 | char i=0;
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121 | for(i=0;i<8;i++)
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122 | {
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123 | if (b & 0x80)
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124 | {
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125 | I2C_SDA_HIGH;
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126 | }
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127 | else
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128 | {
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129 | I2C_SDA_LOW;
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130 | }
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131 | b=b<<1;
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132 | S_DELAY;
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133 | i2c_master_clk_toggle();
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134 | }
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135 | // Auf ACK vom Slave Prüfen
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136 | I2C_SDA_HIGH;
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137 | i2c_master_clk_toggle();
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138 | if(SDA==1)
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139 | {
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140 | return 0;
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141 | }
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142 | else
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143 | {
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144 | return 1;
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145 | }
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146 | }
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147 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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148 | unsigned char i2c_master_read(unsigned char a)
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149 | {
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150 | unsigned char i,c=0b00000000;
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151 | I2C_SDA_HIGH;
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152 |
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153 | for(i=0;i<8;i++)
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154 | {
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155 | c=c<<1;
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156 |
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157 | // Bitweise OR verknüpfen mit dem Eingang, MSB zuerst
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158 | if(SDA_LESE_PIN & (1 << SDA_LESE_BIT)) c|=1;
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159 | i2c_master_clk_toggle();
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160 | }
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161 |
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162 | // ACK oder NACK | ACK=0; NACK=1
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163 | if(a==ACK) {I2C_SDA_LOW;} else {I2C_SDA_HIGH;}
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164 | i2c_master_clk_toggle();
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165 | return c;
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166 | }
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