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| Rev | Author | Line No. | Line |
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| 2222 | - | 1 | /************************************************************************************************************************************** |
| 2 | * File: twimaster.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 void i2c_init(void) |
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| 7 | * void i2c_reset(void) |
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| 8 | * void i2c_start(void) |
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| 9 | * void i2c_stop(void) |
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| 10 | * void i2c_write_byte(unsigned char byte) |
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| 11 | * void I2C_ReceiveByte(void) |
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| 12 | * void I2C_ReceiveLastByte(void) |
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| 13 | * ISR(TWI_vect) |
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| 14 | * |
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| 15 | * hardware: AVR-Ctrl experimental board without LCD display as I2C bus is used |
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| 16 | * |
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| 17 | * Created: Feb 2013 |
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| 18 | * |
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| 19 | * Version: 1.00 experimental version |
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| 20 | * |
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| 21 | * Copyright: (c)2013 dk9nw -at- darc.de |
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| 22 | * All rights reserved. This software is available only for non-commercial amateur radio or educational applications. |
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| 23 | * Other uses are prohibited. This software may be modified only if |
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| 24 | * the resulting code be made available publicly and the original author(s) given credit. |
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| 25 | * |
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| 26 | ******************************************************************************************************************************************/ |
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| 27 | #include "twimaster.h" |
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| 28 | |||
| 29 | unsigned char twi_state = 0; |
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| 30 | volatile unsigned char Motor[4]; // turn rate of the connected electrical motor 0 - 255 |
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| 31 | |||
| 32 | |||
| 33 | // ************************************************************************************************************************** |
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| 34 | // initialize the I2C Bus (TWI) |
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| 35 | // |
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| 36 | void i2c_init(void) |
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| 37 | { |
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| 38 | static unsigned char sreg; |
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| 39 | sreg = SREG; // save backup status register , to be reseted later |
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| 40 | cli(); // switch off I-Bit Global Interrupt |
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| 41 | |||
| 42 | //-------------------------------------------------------------------------------------------------------------------- |
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| 43 | // TWSR = TWI Status Register containing: TWS7 TWS6 TWS5 TWS4 TWS3 – TWPS1 TWPS0 |
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| 44 | // ------------------------- |
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| 45 | // TWPS: TWI Prescaler Bits |
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| 46 | // |
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| 47 | 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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| 48 | |||
| 49 | //-------------------------------------------------------------------------------------------------------------------- |
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| 50 | // TWBR = TWI Bit Rate Register containing: TWBR7 TWBR6 TWBR5 TWBR4 TWBR3 TWBR2 TWBR1 TWBR0 |
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| 51 | // set TWI Bit Rate Register // SCL_frequency = ( CPU_Clock_frequency / ( 16 + 2 * TWBR ) * 4**TWPS ) |
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| 52 | // // |
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| 53 | TWBR = ((SYSCLK/SCL_CLOCK)-16)/2; // TWI Bit Rate (formula is only valid if TWSR=0) |
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| 54 | |||
| 55 | twi_state = 0; |
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| 56 | |||
| 57 | i2c_start(); |
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| 58 | |||
| 59 | SREG = sreg; // write back to old state, |
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| 60 | sei(); // Interrupt is activated again |
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| 61 | } |
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| 62 | // ************************************************************************************************************************** |
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| 63 | |||
| 64 | |||
| 65 | |||
| 66 | // ************************************************************************************************************************** |
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| 67 | // reset I2C Bus |
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| 68 | // |
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| 69 | void i2c_reset(void) |
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| 70 | { |
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| 71 | i2c_stop(); // stop i2c Bus |
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| 72 | twi_state = 0; |
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| 73 | TWCR = (1<<TWINT); // reset to original state incl. interrupt flag reset |
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| 74 | TWAR = 0; |
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| 75 | TWDR = 0; |
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| 76 | TWSR = 0; |
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| 77 | TWBR = 0; |
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| 78 | i2c_init(); // initialize the I2C Bus (TWI) |
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| 79 | i2c_start(); |
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| 80 | i2c_write_byte(0); |
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| 81 | } |
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| 82 | // ************************************************************************************************************************** |
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| 83 | |||
| 84 | |||
| 85 | |||
| 86 | // ************************************************************************************************************************** |
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| 87 | // start of I2C Bus |
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| 88 | // |
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| 89 | void i2c_start(void) |
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| 90 | { |
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| 91 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 92 | // -------------------------------------------------------------------- |
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| 93 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 94 | // TWSTA = TWI start and should be set to one, that TWI is started as Master. |
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| 95 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 96 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 97 | TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN)|(1<<TWIE); |
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| 98 | |||
| 99 | //while( !(TWCR & (1<<TWINT) ) ); // wait, that TWINT is zero again, that means that the start conditions have been transferred |
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| 100 | } |
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| 101 | // ************************************************************************************************************************** |
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| 102 | |||
| 103 | |||
| 104 | |||
| 105 | // ************************************************************************************************************************** |
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| 106 | // stop the I2C Bus |
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| 107 | // |
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| 108 | void i2c_stop(void) |
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| 109 | { |
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| 110 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 111 | // -------------------------------------------------------------------- |
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| 112 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 113 | // TWSTO TWI STOP Condition Bit (TWSTO = 1) -> now will be stoped |
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| 114 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 115 | TWCR = (1<<TWINT)|(1<<TWSTO)|(1<<TWEN); |
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| 116 | } |
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| 117 | // ************************************************************************************************************************** |
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| 118 | |||
| 119 | |||
| 120 | |||
| 121 | |||
| 122 | // ************************************************************************************************************************** |
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| 123 | // Write to I2C |
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| 124 | // |
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| 125 | void i2c_write_byte(unsigned char byte) |
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| 126 | { |
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| 127 | //TWSR = 0x00; // TWI Status Register |
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| 128 | |||
| 129 | TWDR = byte; // move byte to send into TWI Data Register |
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| 130 | |||
| 131 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 132 | // -------------------------------------------------------------------- |
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| 133 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 134 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 135 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 136 | // |
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| 137 | TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE); |
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| 138 | } |
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| 139 | // ************************************************************************************************************************** |
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| 140 | |||
| 141 | |||
| 142 | |||
| 143 | // ************************************************************************************************************************** |
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| 144 | // Receive byte and send ACK |
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| 145 | // |
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| 146 | void I2C_ReceiveByte(void) |
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| 147 | { |
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| 148 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 149 | // --------------------------------------------------------------------------- |
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| 150 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 151 | // TWEA = TWI Acknowledge Bit (TWEA = 1) |
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| 152 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 153 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 154 | // |
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| 155 | TWCR = (1<<TWINT)|(1<<TWEA)|(1<<TWEN)|(1<<TWIE) ; |
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| 156 | } |
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| 157 | // ************************************************************************************************************************** |
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| 158 | |||
| 159 | |||
| 160 | |||
| 161 | // ************************************************************************************************************************** |
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| 162 | // I2C receive last byte and send no ACK |
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| 163 | // |
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| 164 | void I2C_ReceiveLastByte(void) |
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| 165 | { |
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| 166 | // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN – TWIE |
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| 167 | // --------------------------------------------------------------------------- |
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| 168 | // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
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| 169 | // TWEN = TWI enable -> now TWI/I2C is working properly. |
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| 170 | // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
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| 171 | // |
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| 172 | TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE); |
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| 173 | } |
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| 174 | // ************************************************************************************************************************** |
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| 175 | |||
| 176 | |||
| 177 | |||
| 178 | // ************************************************************************************************************************** |
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| 179 | // Interrupt I2C |
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| 180 | //--------------------------------------------------------------------------------------------------------------------------- |
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| 181 | ISR(TWI_vect) |
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| 182 | { |
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| 183 | switch(twi_state++) |
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| 184 | { |
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| 185 | //------------------------------------------------------------------------------------------------------------------- |
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| 186 | // write Motor-Data to BL-Ctrl |
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| 187 | //------------------------------------------------------------------------------------------------------------------- |
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| 188 | case 0: |
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| 189 | i2c_write_byte(0x52); |
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| 190 | break; |
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| 191 | |||
| 192 | case 1: |
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| 193 | i2c_write_byte(Motor[0]); |
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| 194 | break; |
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| 195 | |||
| 196 | case 2: |
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| 197 | i2c_stop(); |
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| 198 | i2c_start(); |
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| 199 | break; |
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| 200 | |||
| 201 | case 3: |
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| 202 | i2c_write_byte(0x54); |
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| 203 | break; |
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| 204 | |||
| 205 | case 4: |
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| 206 | i2c_write_byte(Motor[1]); |
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| 207 | break; |
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| 208 | |||
| 209 | case 5: |
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| 210 | i2c_stop(); |
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| 211 | i2c_start(); |
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| 212 | break; |
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| 213 | |||
| 214 | case 6: |
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| 215 | i2c_write_byte(0x56); |
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| 216 | break; |
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| 217 | |||
| 218 | case 7: |
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| 219 | i2c_write_byte(Motor[2]); |
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| 220 | break; |
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| 221 | |||
| 222 | case 8: |
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| 223 | i2c_stop(); |
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| 224 | i2c_start(); |
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| 225 | break; |
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| 226 | |||
| 227 | case 9: |
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| 228 | i2c_write_byte(0x58); |
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| 229 | break; |
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| 230 | |||
| 231 | case 10: |
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| 232 | i2c_write_byte(Motor[3]); |
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| 233 | break; |
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| 234 | |||
| 235 | case 11: |
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| 236 | i2c_stop(); |
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| 237 | twi_state = 0; |
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| 238 | i2c_start(); |
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| 239 | break; |
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| 240 | |||
| 241 | default: |
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| 242 | twi_state = 0; |
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| 243 | break; |
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| 244 | } |
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| 245 | } |
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| 246 | // EOF ISR(TWI_vect) ***************************************************************************************************** |