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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <util/twi.h>
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#include <util/delay.h>
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//#include "eeprom.h"
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#include "twimaster.h"
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//#include "analog.h"
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#include "configuration.h"
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volatile uint8_t twi_state = TWI_STATE_IDLE;
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volatile uint8_t dac_channel = 0;
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volatile uint16_t I2CTimeout = 100;
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volatile uint8_t DACValues[4];
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uint8_t DACChannel = 0;
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#define SCL_CLOCK  200000L
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#define I2C_TIMEOUT 30000
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/**************************************************
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 * Initialize I2C (TWI)                        
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 **************************************************/
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void I2C_init(void) {
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        uint8_t i;
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        uint8_t sreg = SREG;
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        cli();
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        // SDA is INPUT
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        DDRC &= ~(1 << DDC1);
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        // SCL is output
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        DDRC |= (1 << DDC0);
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        // pull up SDA
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        PORTC |= (1 << PORTC0) | (1 << PORTC1);
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        // TWI Status Register
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        // prescaler 1 (TWPS1 = 0, TWPS0 = 0)
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        TWSR &= ~((1 << TWPS1) | (1 << TWPS0));
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        // set TWI Bit Rate Register
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        TWBR = ((SYSCLK / SCL_CLOCK) - 16) / 2;
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        twi_state = TWI_STATE_IDLE;
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    SREG = sreg;
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}
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/****************************************
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 * Start I2C                          
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 ****************************************/
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void I2C_Start(uint8_t start_state) {
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        twi_state = start_state;
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        // TWI Control Register
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        // clear TWI interrupt flag (TWINT=1)
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        // disable TWI Acknowledge Bit (TWEA = 0)
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        // enable TWI START Condition Bit (TWSTA = 1), MASTER
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        // disable TWI STOP Condition Bit (TWSTO = 0)
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        // disable TWI Write Collision Flag (TWWC = 0)
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        // enable i2c (TWEN = 1)
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        // enable TWI Interrupt (TWIE = 1)
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        TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN) | (1 << TWIE);
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}
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/****************************************
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 * Stop I2C                          
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 ****************************************/
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void I2C_Stop(uint8_t start_state) {
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        twi_state = start_state;
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        // TWI Control Register
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        // clear TWI interrupt flag (TWINT=1)
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        // disable TWI Acknowledge Bit (TWEA = 0)
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        // diable TWI START Condition Bit (TWSTA = 1), no MASTER
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        // enable TWI STOP Condition Bit (TWSTO = 1)
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        // disable TWI Write Collision Flag (TWWC = 0)
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        // enable i2c (TWEN = 1)
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        // disable TWI Interrupt (TWIE = 0)
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        TWCR = (1 << TWINT) | (1 << TWSTO) | (1 << TWEN);
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}
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/****************************************
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 *    Write to I2C                      
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 ****************************************/
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void I2C_WriteByte(int8_t byte) {
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        // move byte to send into TWI Data Register
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        TWDR = byte;
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        // clear interrupt flag (TWINT = 1)
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        // enable i2c bus (TWEN = 1)
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        // enable interrupt (TWIE = 1)
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        TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWIE);
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}
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/****************************************
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 * Receive byte and send ACK        
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 ****************************************/
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void I2C_ReceiveByte(void) {
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        TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWIE) | (1 << TWEA);
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}
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/****************************************
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 * I2C receive last byte and send no ACK
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 ****************************************/
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void I2C_ReceiveLastByte(void) {
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        TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWIE);
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}
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/****************************************
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 * Reset I2C                        
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 ****************************************/
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void I2C_Reset(void) {
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        // stop i2c bus
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        I2C_Stop(TWI_STATE_IDLE);
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        TWCR = (1 << TWINT); // reset to original state incl. interrupt flag reset
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        TWAMR = 0;
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        TWAR = 0;
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        TWDR = 0;
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        TWSR = 0;
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        TWBR = 0;
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        I2C_init();
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}
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/****************************************
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 * I2C ISR
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 ****************************************/
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ISR (TWI_vect)
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{
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        switch (twi_state) { // First i2c_start from SendMotorData()
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        case 0: break;
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                // Writing ADC values.
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        case 7:
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            twi_state++;
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                I2C_WriteByte(0x98); // Address the DAC
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                break;
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        case 8:
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            twi_state++;
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                I2C_WriteByte(0x10 + (DACChannel << 1)); // Select DAC Channel (0x10 = A, 0x12 = B, 0x14 = C)
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                break;
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        case 9:
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            twi_state++;
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                I2C_WriteByte(DACValues[DACChannel]);
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                break;
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        case 10:
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            twi_state++;
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                I2C_WriteByte(0x80); // 2nd byte for all channels is 0x80
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                break;
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        case 11:
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            twi_state++;
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                I2C_Stop(TWI_STATE_IDLE);
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                I2CTimeout = 10;
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                // repeat case 7...10 until all DAC Channels are updated
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                if (DACChannel < 2) {
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                        DACChannel++; // jump to next channel
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                        I2C_Start(TWI_STATE_GYRO_OFFSET_TX); // start transmission for next channel
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                } else {
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                        DACChannel = 0; // reset dac channel counter
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                }
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                break;
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        default:
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                I2C_Stop(TWI_STATE_IDLE);
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                I2CTimeout = 10;
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        }
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}