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| /************************************************************************************************************************************** |
| * File: twimaster.c |
| * |
| * Purpose: controlling I2C |
| * |
| * Functions: int void i2c_init(void) |
| * void i2c_reset(void) |
| * void i2c_start(void) |
| * void i2c_stop(void) |
| * void i2c_write_byte(unsigned char byte) |
| * void I2C_ReceiveByte(void) |
| * void I2C_ReceiveLastByte(void) |
| * ISR(TWI_vect) |
| * |
| * hardware: AVR-Ctrl experimental board without LCD display as I2C bus is used |
| * |
| * Created: Jan 2013 |
| * |
| * Version: 1.00 experimental version |
| * |
| * Copyright: (c)2013 dk9nw -at- darc.de |
| * All rights reserved. This software is available only for non-commercial amateur radio or educational applications. |
| * Other uses are prohibited. This software may be modified only if |
| * the resulting code be made available publicly and the original author(s) given credit. |
| * |
| ******************************************************************************************************************************************/ |
| #include "twimaster.h" |
| |
| unsigned char twi_state = 0; |
| volatile unsigned char Motor[4]; // turn rate of the connected electrical motor 0 - 255 |
| |
| |
| // ************************************************************************************************************************** |
| // initialize the I2C Bus (TWI) |
| // |
| void i2c_init(void) |
| { |
| static unsigned char sreg; |
| sreg = SREG; // save backup status register , to be reseted later |
| cli(); // switch off I-Bit Global Interrupt |
| |
| //-------------------------------------------------------------------------------------------------------------------- |
| // TWSR = TWI Status Register containing: TWS7 TWS6 TWS5 TWS4 TWS3 TWPS1 TWPS0 |
| // ------------------------- |
| // TWPS: TWI Prescaler Bits |
| // |
| 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 |
| |
| //-------------------------------------------------------------------------------------------------------------------- |
| // TWBR = TWI Bit Rate Register containing: TWBR7 TWBR6 TWBR5 TWBR4 TWBR3 TWBR2 TWBR1 TWBR0 |
| // set TWI Bit Rate Register // SCL_frequency = ( CPU_Clock_frequency / ( 16 + 2 * TWBR ) * 4**TWPS ) |
| // // |
| TWBR = ((SYSCLK/SCL_CLOCK)-16)/2; // TWI Bit Rate (formula is only valid if TWSR=0) |
| |
| twi_state = 0; |
| |
| i2c_start(); |
| |
| SREG = sreg; // write back to old state, |
| sei(); // Interrupt is activated again |
| } |
| // ************************************************************************************************************************** |
| |
| |
| |
| // ************************************************************************************************************************** |
| // reset I2C Bus |
| // |
| void i2c_reset(void) |
| { |
| i2c_stop(); // stop i2c Bus |
| twi_state = 0; |
| TWCR = (1<<TWINT); // reset to original state incl. interrupt flag reset |
| TWAR = 0; |
| TWDR = 0; |
| TWSR = 0; |
| TWBR = 0; |
| i2c_init(); // initialize the I2C Bus (TWI) |
| i2c_start(); |
| i2c_write_byte(0); |
| } |
| // ************************************************************************************************************************** |
| |
| |
| |
| // ************************************************************************************************************************** |
| // start of I2C Bus |
| // |
| void i2c_start(void) |
| { |
| // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN TWIE |
| // -------------------------------------------------------------------- |
| // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
| // TWSTA = TWI start and should be set to one, that TWI is started as Master. |
| // TWEN = TWI enable -> now TWI/I2C is working properly. |
| // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
| TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN)|(1<<TWIE); |
| |
| //while( !(TWCR & (1<<TWINT) ) ); // wait, that TWINT is zero again, that means that the start conditions have been transferred |
| } |
| // ************************************************************************************************************************** |
| |
| |
| |
| // ************************************************************************************************************************** |
| // stop the I2C Bus |
| // |
| void i2c_stop(void) |
| { |
| // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN TWIE |
| // -------------------------------------------------------------------- |
| // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
| // TWSTO TWI STOP Condition Bit (TWSTO = 1) -> now will be stoped |
| // TWEN = TWI enable -> now TWI/I2C is working properly. |
| TWCR = (1<<TWINT)|(1<<TWSTO)|(1<<TWEN); |
| } |
| // ************************************************************************************************************************** |
| |
| |
| |
| |
| // ************************************************************************************************************************** |
| // Write to I2C |
| // |
| void i2c_write_byte(unsigned char byte) |
| { |
| //TWSR = 0x00; // TWI Status Register |
| |
| TWDR = byte; // move byte to send into TWI Data Register |
| |
| // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN TWIE |
| // -------------------------------------------------------------------- |
| // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
| // TWEN = TWI enable -> now TWI/I2C is working properly. |
| // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
| TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE); |
| } |
| // ************************************************************************************************************************** |
| |
| |
| |
| // ************************************************************************************************************************** |
| // Receive byte and send ACK |
| // |
| void I2C_ReceiveByte(void) |
| { |
| // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN TWIE |
| // --------------------------------------------------------------------------- |
| // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
| // TWEA = TWI Acknowledge Bit (TWEA = 1) |
| // TWEN = TWI enable -> now TWI/I2C is working properly. |
| // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
| // |
| TWCR = (1<<TWINT)|(1<<TWEA)|(1<<TWEN)|(1<<TWIE) ; |
| } |
| // ************************************************************************************************************************** |
| |
| |
| |
| // ************************************************************************************************************************** |
| // I2C receive last byte and send no ACK |
| // |
| void I2C_ReceiveLastByte(void) |
| { |
| // TWCR = TWI Control Register -> TWINT TWEA TWSTA TWSTO TWWC TWEN TWIE |
| // --------------------------------------------------------------------------- |
| // TWINT = TWI interrupt flag - to be set to one, to reset the TWINT Flag . |
| // TWEN = TWI enable -> now TWI/I2C is working properly. |
| // TWIE = TWI Interrupt enable is the TWIE Bit -> should be set |
| TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE); |
| } |
| // ************************************************************************************************************************** |
| |
| |
| |
| // ************************************************************************************************************************** |
| // Interrupt I2C |
| //--------------------------------------------------------------------------------------------------------------------------- |
| ISR(TWI_vect) |
| { |
| switch(twi_state++) |
| { |
| //------------------------------------------------------------------------------------------------------------------- |
| // write Motor-Data to BL-Ctrl |
| //------------------------------------------------------------------------------------------------------------------- |
| case 0: |
| i2c_write_byte(0x52); |
| break; |
| |
| case 1: |
| i2c_write_byte(Motor[0]); |
| break; |
| |
| case 2: |
| i2c_stop(); |
| i2c_start(); |
| break; |
| |
| case 3: |
| i2c_write_byte(0x54); |
| break; |
| |
| case 4: |
| i2c_write_byte(Motor[1]); |
| break; |
| |
| case 5: |
| i2c_stop(); |
| i2c_start(); |
| break; |
| |
| case 6: |
| i2c_write_byte(0x56); |
| break; |
| |
| case 7: |
| i2c_write_byte(Motor[2]); |
| break; |
| |
| case 8: |
| i2c_stop(); |
| i2c_start(); |
| break; |
| |
| case 9: |
| i2c_write_byte(0x58); |
| break; |
| |
| case 10: |
| i2c_write_byte(Motor[3]); |
| break; |
| |
| case 11: |
| i2c_stop(); |
| twi_state = 0; |
| i2c_start(); |
| break; |
| |
| default: |
| twi_state = 0; |
| break; |
| } |
| } |
| // EOF ISR(TWI_vect) ***************************************************************************************************** |