1 | #include <avr/io.h>
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2 | #ifndef F_CPU
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3 | #define F_CPU 8000000UL /* Quarz mit 8 Mhz */
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4 | #endif
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5 | #include <util/delay.h>
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6 | #include <util/twi.h>
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7 | #include <avr/interrupt.h>
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8 | #include <stdlib.h> //fuer NULL
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9 |
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10 | //TWI SLAVE EINSTELLUNGEN
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11 | #define TWI_BIT_RATE 40
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12 | #define TWI_PRESCALER 0
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13 | #define TWI_EIGENE_ADRESSE 120 //eigene SLAVE ADRESSE 1...127
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14 | #define TWI_ADRESSE_SLAVE 127
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15 |
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16 | #define TWI_GENERAL_CALL_enable 0 //1=Generral Call enabled / 0=disabled
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17 |
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18 |
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19 |
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20 | unsigned char DATENTABELLE [30] [3]; //2 Dimensionales Array - Speicherort aller zu sendenden Daten
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21 | #define GOESSE_DATENTABELLE_IN_BYTES 90
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22 | unsigned char *LAUFENDER_ZEIGER_AUF_DATENTABELLE = NULL;
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23 |
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24 | unsigned char TWI_EMPFANGENE_DATEN [1] [3]; //2 Dimensionales Array - Speicherort fuer ueber TWI empfangene Daten
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25 | unsigned char *LAUFENDER_ZEIGER_AUF_TWI_EMPFANGENE_DATEN = NULL;
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26 |
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27 |
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28 | unsigned char TWI_BUSY_FLAG = 0;
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29 |
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30 |
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31 | void init_twi() {
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32 | TWBR = TWI_BIT_RATE;
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33 | TWSR = TWI_PRESCALER;
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34 | TWAR = (TWI_EIGENE_ADRESSE << 1 | TWI_GENERAL_CALL_enable << TWGCE);
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35 | TWCR = (0<<TWINT | 1<<TWEA | 1<<TWEN | 1<<TWIE);
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36 | }
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37 |
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38 |
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39 |
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40 | unsigned char next_byte() {
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41 | unsigned char temp_char = *LAUFENDER_ZEIGER_AUF_DATENTABELLE;
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42 | LAUFENDER_ZEIGER_AUF_DATENTABELLE ++ ;
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43 | return temp_char;
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44 | }
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45 |
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46 |
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47 |
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48 | ISR(TWI_vect){ //Two-wire Serial Interface Handler
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49 |
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50 | switch (TWSR & 0xF8){
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51 |
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52 | //MASTER TRANSMITTER
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53 |
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54 | case TW_START: //start condition transmitted
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55 | //Load SLA + "W" (W=0)
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56 | TWDR = (127 << 1); //general call
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57 | TWCR = (1<<TWINT) | (1<<TWEN| 1<<TWIE); //send SLA + "W" (W=0)
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58 | PORTB &= ~(1<<PB5);
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59 | break;
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60 |
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61 | case TW_MT_SLA_ACK: //SLA+W transmitted, ACK received
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62 | //Load data byte
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63 | TWDR = next_byte();
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64 | //senden - Clear TWINT
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65 | TWCR = (1<<TWINT) | (1<<TWEN| 1<<TWIE);
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66 | PORTB &= ~(1<<PB4);
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67 | break;
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68 |
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69 | case TW_MT_DATA_ACK: //data transmitted, ACK received
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70 |
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71 | if (LAUFENDER_ZEIGER_AUF_DATENTABELLE > ((&DATENTABELLE[0][0]) + 90)){ //Zeiger ausserhalb der DATENTABLELLE
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72 |
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73 | //transmit STOP condition
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74 | TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO| 1<<TWIE );
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75 | PORTB &= ~(1<<PB2);
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76 | TWI_BUSY_FLAG = 0; //es darf erneut gesendet werden
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77 |
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78 | }
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79 | else {
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80 | //Load data byte
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81 | TWDR = next_byte();
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82 | //senden - Clear TWINT
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83 | TWCR = (1<<TWINT) | (1<<TWEN| 1<<TWIE);
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84 | PORTB &= ~(1<<PB3);
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85 | }
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86 | break;
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87 |
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88 | //ERROR
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89 | PORTD &= ~(1 << PD0);
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90 |
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91 |
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92 | }
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93 | }
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94 |
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95 |
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96 |
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97 | void TWI_MASTER_TRANSMITTER(){
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98 |
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99 | LAUFENDER_ZEIGER_AUF_DATENTABELLE = &DATENTABELLE[0][0]; //Zeiger auf Adresse "DATENTABELLE [0][0]"
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100 | //transmit START condition
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101 |
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102 | PORTB = 0xFF;
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103 | PORTB &= ~(1<<PB0);
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104 | TWCR = (1<<TWINT|1<<TWSTA|1<<TWEN |1<<TWIE);
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105 |
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106 | _delay_ms(10);
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107 | }
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108 |
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109 |
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110 |
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111 |
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112 | int main (void) {
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113 | DDRB = 0xFF; //Alle Pins auf Ausgang
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114 | PORTB = 0xFF;
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115 | DDRD = 0xFF; //Alle Pins auf Ausgang
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116 | PORTD = 0xFF;
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117 | DDRC = 0x00; //PORT C alles EINGÄNGE
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118 |
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119 |
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120 | init_twi(); //TWI INITIALISIERUNG
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121 | _delay_ms(4000);
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122 |
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123 | sei(); //Interrupts global freigeben
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124 |
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125 | while (1) {
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126 |
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127 | if (TWI_BUSY_FLAG == 0) {
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128 | PORTB = 0xFF;
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129 | TWI_BUSY_FLAG = 1;
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130 | TWI_MASTER_TRANSMITTER();
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131 | }
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132 |
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133 |
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134 | } //End while
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135 | return 0;
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136 | } //End main
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