1 | #ifndef F_CPU
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2 | #define F_CPU 8000000UL
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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 DDRC // Register für die I2C Kommunikation
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9 | #define I2C_DDR_REG_BIT DDC7 //
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10 | #define I2C_PORT PORTC // I2C Port definition
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11 |
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12 | #define SCL PC6 // Port C Pin 6
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13 | #define SDA PC7 // Port C Pin 7
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14 |
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15 | #define SDA_LESE_PIN PINC
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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() // Daten Leitung 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
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44 | #define M_DELAY _delay_us(1);
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45 | #define DELAY _delay_ms(1);
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46 |
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47 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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48 | unsigned char i2c_try_scl(unsigned char start_trials)
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49 | {
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50 | // 10 Mal kurz warten, wenn SCL auf LOW gehalten wird
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51 | while((!SCL) && (start_trials <50))
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52 | {
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53 | start_trials++;
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54 | S_DELAY;
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55 | }
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56 | if(!SCL) return 0 ; return 1;
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57 | }
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58 |
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59 | void i2c_master_stop(void);
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60 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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61 |
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62 | ////////////////////////////////////////////////////////////////////////////////////////////
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63 | // I2C-Master Interface Standard Routinen
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64 | ////////////////////////////////////////////////////////////////////////////////////////////
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65 | void i2c_master_init(void)
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66 | {
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67 | I2C_DDR |= (1<<SCL); // SCL Leitung als Ausgang definieren
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68 | S_DELAY;
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69 | I2C_SCL_HIGH; // Cockleitung auf H setzen
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70 | I2C_SDA_HIGH; // Datenleitung auf H setzen
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71 | S_DELAY; // kurz warten
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72 | i2c_master_stop();
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73 | }
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74 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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75 | void i2c_master_clk_toggle(void)
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76 | {
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77 | i2c_try_scl(0x0A);
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78 |
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79 | I2C_SCL_HIGH;
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80 | S_DELAY;
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81 | S_DELAY;
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82 | I2C_SCL_LOW;
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83 | S_DELAY;
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84 | }
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85 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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86 | void i2c_master_start(void){
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87 | // Übergang von H->L auf SDA, wobei SCL H ist.
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88 | i2c_try_scl(0x0A);
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89 |
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90 | I2C_SDA_HIGH; // SDA vorsichtshalber auf HIGH ziehen
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91 | // S_DELAY;
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92 | I2C_SCL_HIGH; // SCL auf High
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93 | S_DELAY;
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94 | I2C_SDA_LOW; // SDA auf Low ziehen
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95 | M_DELAY;
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96 | M_DELAY;
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97 | M_DELAY;
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98 | I2C_SCL_LOW; // SCL auf low
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99 | S_DELAY;
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100 | }
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101 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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102 | void i2c_master_stop(void)
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103 | {
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104 | // Übergang von L->H auf SDA, wobei SCL H ist.
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105 | i2c_try_scl(0x0A);
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106 | S_DELAY;
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107 | I2C_SDA_LOW; // SDA vorsichtshalber auf LOW ziehen
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108 | S_DELAY; // Kurz abwarten
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109 | I2C_SCL_HIGH; // SCL auf High setzen
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110 | S_DELAY;
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111 | I2C_SDA_HIGH; // SDA von L auf H ziehen
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112 | S_DELAY;
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113 | }
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114 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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115 | unsigned char i2c_master_write(unsigned char b)
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116 | {
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117 | char i=0;
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118 | for(i=0;i<8;i++)
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119 | {
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120 | if (b & 0x80) // Wenn höchstes Bit=1
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121 | {
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122 | I2C_SDA_HIGH;
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123 | }
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124 | else // Wenn höchstes Bit=0
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125 | {
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126 | I2C_SDA_LOW;
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127 | }
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128 | b=b<<1; // Daten Linksshift
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129 | S_DELAY;
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130 | i2c_master_clk_toggle();
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131 | }
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132 | // Auf ACK vom Slave Prüfen
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133 | I2C_SDA_HIGH;
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134 | i2c_master_clk_toggle();
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135 | if(SDA==1)
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136 | {
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137 | return 0;
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138 | }
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139 | else
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140 | {
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141 | return 1;
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142 | }
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143 | }
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144 | /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
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145 | unsigned char i2c_master_read(unsigned char a)
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146 | {
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147 | unsigned char i,c=0b00000000;
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148 | I2C_SDA_HIGH;
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149 |
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150 | for(i=0;i<8;i++)
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151 | {
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152 | c=c<<1;
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153 |
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154 | // Bitweise OR verknüpfen mit dem Eingang, MSB zuerst
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155 | if(SDA_LESE_PIN & (1 << SDA_LESE_BIT)) c|=1;
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156 | i2c_master_clk_toggle();
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157 | }
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158 |
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159 | // ACK oder NACK | ACK=0; NACK=1
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160 | if(a==ACK) {I2C_SDA_LOW;} else {I2C_SDA_HIGH;}
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161 | i2c_master_clk_toggle();
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162 | return c;
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163 | }
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164 |
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165 |
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166 | int main(void)
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167 | { DDRD=0b00000000;
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168 | DDRB=0b11111111;
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169 | uint8_t low_byte=0b00001000;
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170 |
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171 | while(1)
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172 | {
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173 | switch(PIND){
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174 | case 0b11111110:
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175 | PORTB=0b00000000;
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176 | i2c_master_start();
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177 | i2c_master_write(0xE0);
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178 | i2c_master_write(0x00);
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179 | i2c_master_write(0x51);
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180 | i2c_master_stop();
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181 | break;
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182 |
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183 | case 0b11111101:
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184 | i2c_master_start();
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185 | i2c_master_write(0xE0);
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186 | i2c_master_write(0x03);
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187 | i2c_master_stop();
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188 | i2c_master_start();
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189 | i2c_master_write(0xE1);
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190 | low_byte=i2c_master_read(1);
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191 | i2c_master_stop();
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192 | break;
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193 |
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194 | case 0b11011111:
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195 | PORTB=low_byte;
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196 | break;
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197 |
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198 | default:
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199 | PORTB=0b11111111;
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200 |
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201 |
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202 | }
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203 | }
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204 |
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205 | }
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