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