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1 ingob 1
/*############################################################################
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############################################################################*/
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#include <avr/io.h>
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#include <avr/interrupt.h>
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1 ingob 7
#include "main.h"
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#include "twimaster.h"
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#include "fc.h"
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volatile uint8_t twi_state = 0;
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volatile uint8_t motor = 0;
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volatile uint8_t motor_rx[8];
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/**************************************************/
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/*   Initialize I2C (TWI)                         */
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/**************************************************/
1 ingob 18
void i2c_init(void)
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{
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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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        SREG = sreg;
1 ingob 38
}
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/****************************************/
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/*   Start I2C                          */
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/****************************************/
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void i2c_start(void)
1 ingob 44
{
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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 (TWIE = 1)
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        // enable TWI Interrupt (TWIE = 1)
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    TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN) | (1<<TWIE);
1 ingob 54
}
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/****************************************/
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/*    Stop I2C                          */
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/****************************************/
1 ingob 59
void i2c_stop(void)
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{
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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 (TWIE = 1)
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        // disable TWI Interrupt (TWIE = 0)
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    TWCR = (1<<TWINT) | (1<<TWSTO) | (1<<TWEN);
1 ingob 70
}
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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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{
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        // stop i2c bus
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        i2c_stop();
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        twi_state = 0;
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        motor = TWDR; // ??
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        motor = 0;
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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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        i2c_start();
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        i2c_write_byte(0);
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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_write_byte(int8_t byte)
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{
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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 intterupt (TWIW = 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_receive_byte(void)
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{
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   TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWIE) | (1<<TWEA);
1 ingob 113
}
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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_receive_last_byte(void)
1 ingob 119
{
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   TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWIE);
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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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        static uint8_t motorread = 0;
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    switch (twi_state++) // First i2s_start from SendMotorData()
1 ingob 133
        {
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                // Master Transmit
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        case 0: // Send SLA-W
1 ingob 136
                i2c_write_byte(0x52+(motor*2));
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                break;
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        case 1: // Send Data to Salve
1 ingob 139
                switch(motor++)
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                    {
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                    case 0:
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                            i2c_write_byte(Motor_Front);
1 ingob 143
                            break;
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                    case 1:
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                            i2c_write_byte(Motor_Rear);
1 ingob 146
                            break;
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                    case 2:
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                            i2c_write_byte(Motor_Right);
1 ingob 149
                            break;
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                    case 3:
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                            i2c_write_byte(Motor_Left);
1 ingob 152
                            break;
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                    }
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                break;
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        case 2: // repeat case 0+1 for all Slaves
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                if (motor<4) twi_state = 0;
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                i2c_start(); // Repeated start -> switch salve or switch Master Transmit -> Master Receive
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                break;
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        // Master Receive
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        case 3: // Send SLA-R
1 ingob 162
                i2c_write_byte(0x53+(motorread*2));
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                break;
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        case 4:
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                //Transmit 1st byte
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                                i2c_receive_byte();
1 ingob 167
                break;
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        case 5: //Read 1st byte and transmit 2nd Byte
1 ingob 169
                motor_rx[motorread] = TWDR;
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                                i2c_receive_last_byte();
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                                break;
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        case 6:
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                //Read 2nd byte
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                                motor_rx[motorread+4] = TWDR;
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                                motorread++;
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                if (motorread > 3) motorread=0;
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        default:
1 ingob 179
                i2c_stop();
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                twi_state = 0;
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                I2CTimeout = 10;
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                motor = 0;
1 ingob 183
        }
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}