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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2205 | - | 1 | /************************************************************************************************************************************** |
| 2 | * File: I2Cmaster.c |
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| 3 | * |
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| 4 | * Purpose: controlling I2C |
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| 5 | * |
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| 6 | * Functions: int main(void) |
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| 7 | * |
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| 8 | * hardware: AVR-Ctrl experimental board without LCD display as I2C bus is used |
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| 9 | * |
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| 10 | * Created: Jan 2013 |
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| 11 | * |
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| 12 | * Version: 1.00 experimental version |
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| 13 | * |
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| 14 | * Copyright: (c)2013 dk9nw -at- darc.de |
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| 15 | * All rights reserved. This software is available only for non-commercial amateur radio or educational applications. |
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| 16 | * Other uses are prohibited. This software may be modified only if |
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| 17 | * the resulting code be made available publicly and the original author(s) given credit. |
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| 18 | * |
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| 19 | ******************************************************************************************************************************************/ |
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| 20 | #include "I2Cmaster.h" |
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| 21 | |||
| 22 | unsigned char twi_state = 0; |
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| 23 | volatile unsigned char Motor[4]; // turn rate of the connected electrical motor 0 - 255 |
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| 24 | |||
| 25 | |||
| 26 | // ************************************************************************************************************************** |
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| 27 | // initialize the I2C Bus (TWI) |
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| 28 | // |
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| 29 | void i2c_init(void) |
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| 30 | { |
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| 31 | static unsigned char sreg; |
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| 32 | sreg = SREG; // save backup status register , to be reseted later |
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| 33 | cli(); // switch off I-Bit Global Interrupt |
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| 34 | |||
| 35 | //-------------------------------------------------------------------------------------------------------------------- |
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| 36 | // TWSR = TWI Status Register containing: TWS7 TWS6 TWS5 TWS4 TWS3 – TWPS1 TWPS0 |
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| 37 | // ------------------------- |
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| 38 | // TWPS: TWI Prescaler Bits |
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| 39 | // |
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| 40 | TWSR &= ~((1<<TWPS1)|(1<<TWPS0)); // TWI Status Register Bits 1..0 – TWPS: TWI Prescaler Bits 00=1:1 01=1:4 10=1:16 11=1:64 |
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| 41 | |||
| 42 | //-------------------------------------------------------------------------------------------------------------------- |
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| 43 | // TWBR = TWI Bit Rate Register containing: TWBR7 TWBR6 TWBR5 TWBR4 TWBR3 TWBR2 TWBR1 TWBR0 |
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| 44 | // set TWI Bit Rate Register // SCL_frequency = ( CPU_Clock_frequency / ( 16 + 2 * TWBR ) * 4**TWPS ) |
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| 45 | // // |
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| 46 | TWBR = ((SYSCLK/SCL_CLOCK)-16)/2; // TWI Bit Rate (formula is only valid if TWSR=0) |
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| 47 | |||
| 48 | twi_state = 0; |
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| 49 | |||
| 50 | i2c_start(); |
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| 51 | |||
| 52 | SREG = sreg; // write back to old state, |
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| 53 | sei(); // Interrupt is activated again |
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| 54 | } |
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| 55 | // ************************************************************************************************************************** |
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| 56 | |||
| 57 | |||
| 58 | |||
| 59 | // ************************************************************************************************************************** |
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| 60 | // reset I2C Bus |
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| 61 | // |
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| 62 | void i2c_reset(void) |
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| 63 | { |
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| 64 | i2c_stop(); // stop i2c Bus |
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| 65 | twi_state = 0; |
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| 66 | TWCR = (1<<TWINT); // reset to original state incl. interrupt flag reset |
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| 67 | TWAR = 0; |
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| 68 | TWDR = 0; |
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| 69 | TWSR = 0; |
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| 70 | TWBR = 0; |
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| 71 | i2c_init(); // initialize the I2C Bus (TWI) |
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| 72 | i2c_start(); |
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| 73 | i2c_write_byte(0); |
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| 74 | } |
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| 75 | // ************************************************************************************************************************** |
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| 76 | |||
| 77 | |||
| 78 | |||
| 79 | // ************************************************************************************************************************** |
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| 80 | // start of I2C Bus |
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| 81 | // |
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| 82 | void i2c_start(void) |
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| 83 | { |
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| 84 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 85 | // -------------------------------------------------------------------- |
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| 86 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 87 | // TWSTA = TWI start and should be set to one, that TWI is started as Master. |
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| 88 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 89 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 90 | TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN)|(1<<TWIE); |
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| 91 | |||
| 92 | //while( !(TWCR & (1<<TWINT) ) ); // wait, that TWINT is zero again, that means that the start conditions have been transferred |
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| 93 | } |
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| 94 | // ************************************************************************************************************************** |
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| 95 | |||
| 96 | |||
| 97 | |||
| 98 | // ************************************************************************************************************************** |
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| 99 | // stop the I2C Bus |
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| 100 | // |
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| 101 | void i2c_stop(void) |
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| 102 | { |
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| 103 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 104 | // -------------------------------------------------------------------- |
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| 105 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 106 | // TWSTO TWI STOP Condition Bit (TWSTO = 1) -> now will be stoped |
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| 107 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 108 | TWCR = (1<<TWINT)|(1<<TWSTO)|(1<<TWEN); |
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| 109 | } |
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| 110 | // ************************************************************************************************************************** |
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| 111 | |||
| 112 | |||
| 113 | |||
| 114 | |||
| 115 | // ************************************************************************************************************************** |
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| 116 | // Write to I2C |
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| 117 | // |
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| 118 | void i2c_write_byte(unsigned char byte) |
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| 119 | { |
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| 120 | //TWSR = 0x00; // TWI Status Register |
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| 121 | |||
| 122 | TWDR = byte; // move byte to send into TWI Data Register |
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| 123 | |||
| 124 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 125 | // -------------------------------------------------------------------- |
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| 126 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 127 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 128 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 129 | TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE); |
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| 130 | } |
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| 131 | // ************************************************************************************************************************** |
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| 132 | |||
| 133 | |||
| 134 | |||
| 135 | // ************************************************************************************************************************** |
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| 136 | // Receive byte and send ACK |
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| 137 | // |
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| 138 | void I2C_ReceiveByte(void) |
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| 139 | { |
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| 140 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 141 | // --------------------------------------------------------------------------- |
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| 142 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 143 | // TWEA = TWI Acknowledge Bit (TWEA = 1) |
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| 144 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 145 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 146 | // |
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| 147 | TWCR = (1<<TWINT)|(1<<TWEA)|(1<<TWEN)|(1<<TWIE) ; |
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| 148 | } |
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| 149 | // ************************************************************************************************************************** |
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| 150 | |||
| 151 | |||
| 152 | |||
| 153 | // ************************************************************************************************************************** |
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| 154 | // I2C receive last byte and send no ACK |
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| 155 | // |
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| 156 | void I2C_ReceiveLastByte(void) |
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| 157 | { |
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| 158 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 159 | // --------------------------------------------------------------------------- |
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| 160 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 161 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 162 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 163 | TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE); |
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| 164 | } |
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| 165 | // ************************************************************************************************************************** |
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| 166 | |||
| 167 | |||
| 168 | |||
| 169 | // ************************************************************************************************************************** |
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| 170 | // Interrupt I2C |
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| 171 | //--------------------------------------------------------------------------------------------------------------------------- |
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| 172 | ISR(TWI_vect) |
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| 173 | { |
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| 174 | switch(twi_state++) |
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| 175 | { |
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| 176 | //------------------------------------------------------------------------------------------------------------------- |
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| 177 | // write Motor-Data to BL-Ctrl |
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| 178 | //------------------------------------------------------------------------------------------------------------------- |
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| 179 | case 0: |
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| 180 | i2c_write_byte(0x52); |
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| 181 | break; |
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| 182 | |||
| 183 | case 1: |
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| 184 | i2c_write_byte(Motor[0]); |
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| 185 | break; |
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| 186 | |||
| 187 | case 2: |
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| 188 | i2c_stop(); |
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| 189 | i2c_start(); |
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| 190 | break; |
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| 191 | |||
| 192 | case 3: |
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| 193 | i2c_write_byte(0x54); |
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| 194 | break; |
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| 195 | |||
| 196 | case 4: |
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| 197 | i2c_write_byte(Motor[1]); |
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| 198 | break; |
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| 199 | |||
| 200 | case 5: |
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| 201 | i2c_stop(); |
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| 202 | i2c_start(); |
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| 203 | break; |
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| 204 | |||
| 205 | case 6: |
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| 206 | i2c_write_byte(0x56); |
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| 207 | break; |
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| 208 | |||
| 209 | case 7: |
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| 210 | i2c_write_byte(Motor[2]); |
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| 211 | break; |
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| 212 | |||
| 213 | case 8: |
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| 214 | i2c_stop(); |
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| 215 | i2c_start(); |
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| 216 | break; |
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| 217 | |||
| 218 | case 9: |
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| 219 | i2c_write_byte(0x58); |
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| 220 | break; |
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| 221 | |||
| 222 | case 10: |
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| 223 | i2c_write_byte(Motor[3]); |
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| 224 | break; |
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| 225 | |||
| 226 | case 11: |
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| 227 | i2c_stop(); |
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| 228 | twi_state = 0; |
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| 229 | i2c_start(); |
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| 230 | break; |
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| 231 | |||
| 232 | default: |
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| 233 | twi_state = 0; |
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| 234 | break; |
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| 235 | } |
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| 236 | } |
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| 237 | // EOF ISR(TWI_vect) ***************************************************************************************************** |