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#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/twi.h>
#include <util/delay.h>
#include "twimaster.h"
#include "configuration.h"
#include "analog.h"
#include "printf_P.h"

volatile uint8_t twi_state = TWI_STATE_MOTOR_TX;
volatile uint8_t dac_channel = 0;
volatile uint8_t motor_write = 0;
volatile uint8_t motor_read = 0;
volatile uint16_t I2CTimeout = 100;
uint8_t missingMotor = 0;

motorData_t motor[MAX_MOTORS];

uint8_t DACChannel = 0;

#define SCL_CLOCK  200000L
#define I2C_TIMEOUT 30000

/**************************************************
 * Initialize I2C (TWI)                        
 **************************************************/

void I2C_init(void) {
        uint8_t i;
        uint8_t sreg = SREG;
        cli();

        // SDA is INPUT
        DDRC &= ~(1 << DDC1);
        // SCL is output
        DDRC |= (1 << DDC0);
        // pull up SDA
        PORTC |= (1 << PORTC0) | (1 << PORTC1);

        // TWI Status Register
        // prescaler 1 (TWPS1 = 0, TWPS0 = 0)
        TWSR &= ~((1 << TWPS1) | (1 << TWPS0));

        // set TWI Bit Rate Register
        TWBR = ((SYSCLK / SCL_CLOCK) - 16) / 2;

        twi_state = TWI_STATE_MOTOR_TX;
        motor_write = 0;
        motor_read = 0;

        for (i = 0; i < MAX_MOTORS; i++) {
                motor[i].throttle = 0;
                motor[i].present = 0;
                motor[i].maxPWM = 0;
        }

        SREG = sreg;
}

/****************************************
 * Start I2C                          
 ****************************************/

void I2C_Start(uint8_t start_state) {
        twi_state = start_state;
        // TWI Control Register
        // clear TWI interrupt flag (TWINT=1)
        // disable TWI Acknowledge Bit (TWEA = 0)
        // enable TWI START Condition Bit (TWSTA = 1), MASTER
        // disable TWI STOP Condition Bit (TWSTO = 0)
        // disable TWI Write Collision Flag (TWWC = 0)
        // enable i2c (TWEN = 1)
        // enable TWI Interrupt (TWIE = 1)
        TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN) | (1 << TWIE);
}

/****************************************
 * Stop I2C                          
 ****************************************/

void I2C_Stop(uint8_t start_state) {
        twi_state = start_state;
        // TWI Control Register
        // clear TWI interrupt flag (TWINT=1)
        // disable TWI Acknowledge Bit (TWEA = 0)
        // diable TWI START Condition Bit (TWSTA = 1), no MASTER
        // enable TWI STOP Condition Bit (TWSTO = 1)
        // disable TWI Write Collision Flag (TWWC = 0)
        // enable i2c (TWEN = 1)
        // disable TWI Interrupt (TWIE = 0)
        TWCR = (1 << TWINT) | (1 << TWSTO) | (1 << TWEN);
}

/****************************************
 *    Write to I2C                      
 ****************************************/

void I2C_WriteByte(int8_t byte) {
        // move byte to send into TWI Data Register
        TWDR = byte;
        // clear interrupt flag (TWINT = 1)
        // enable i2c bus (TWEN = 1)
        // enable interrupt (TWIE = 1)
        TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWIE);
}

/****************************************
 * Receive byte and send ACK        
 ****************************************/

void I2C_ReceiveByte(void) {
        TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWIE) | (1 << TWEA);
}

/****************************************
 * I2C receive last byte and send no ACK
 ****************************************/

void I2C_ReceiveLastByte(void) {
        TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWIE);
}

/****************************************
 * Reset I2C                        
 ****************************************/

void I2C_Reset(void) {
        // stop i2c bus
        I2C_Stop(TWI_STATE_MOTOR_TX);
        twi_state = 0;
        motor_write = TWDR;
        motor_write = 0;
        motor_read = 0;
        TWCR = (1 << TWINT); // reset to original state incl. interrupt flag reset
        TWAMR = 0;
        TWAR = 0;
        TWDR = 0;
        TWSR = 0;
        TWBR = 0;
        I2C_init();
        I2C_Start(TWI_STATE_MOTOR_TX);
}

/****************************************
 * I2C ISR
 ****************************************/

ISR (TWI_vect)
{
        static uint8_t missing_motor = 0;
        switch (twi_state++) { // First i2c_start from SendMotorData()
        // Master Transmit
        case 0: // TWI_STATE_MOTOR_TX
                // skip motor if not used in mixer
                while ((mixerMatrix.motor[motor_write][MIX_THROTTLE] <= 0) && (motor_write < MAX_MOTORS))
                        motor_write++;
                if (motor_write >= MAX_MOTORS) { // writing finished, read now
                        motor_write = 0;
                        twi_state = TWI_STATE_MOTOR_RX;
                        I2C_WriteByte(0x53 + (motor_read * 2)); // select slave adress in rx mode
                } else
                        I2C_WriteByte(0x52 + (motor_write * 2)); // select slave adress in tx mode
                break;
        case 1: // Send Data to Slave
                I2C_WriteByte(motor[motor_write].throttle); // transmit throttle value.
                break;
        case 2: // repeat case 0+1 for all motors
                if (TWSR == TW_MT_DATA_NACK) { // Data transmitted, NACK received
                        if (!missing_motor)
                                missing_motor = motor_write + 1;
                        if (++motor[motor_write].error == 0)
                                motor[motor_write].error = 255; // increment error counter and handle overflow
                }
                I2C_Stop(TWI_STATE_MOTOR_TX);
                I2CTimeout = 10;
                motor_write++; // next motor
                I2C_Start(TWI_STATE_MOTOR_TX); // Repeated start -> switch slave or switch Master Transmit -> Master Receive
                break;
                // Master Receive Data
        case 3:
                if (TWSR != TW_MR_SLA_ACK) { //  SLA+R transmitted, if not ACK received
                        // no response from the addressed slave received
                        motor[motor_read].present = 0;
                        motor_read++; // next motor
                        if (motor_read >= MAX_MOTORS)
                                motor_read = 0; // restart reading of first motor if we have reached the last one
                        I2C_Stop(TWI_STATE_MOTOR_TX);
                } else {
                        motor[motor_read].present = ('1' - '-') + motor_read;
                        I2C_ReceiveByte(); //Transmit 1st byte
                }
                missingMotor = missing_motor;
                missing_motor = 0;
                break;
        case 4: //Read 1st byte and transmit 2nd Byte
                motor[motor_read].current = TWDR;
                I2C_ReceiveLastByte(); // nack
                break;
        case 5:
                //Read 2nd byte
                motor[motor_read].maxPWM = TWDR;
                motor_read++; // next motor
                if (motor_read >= MAX_MOTORS)
                        motor_read = 0; // restart reading of first motor if we have reached the last one
                I2C_Stop(TWI_STATE_MOTOR_TX);
                break;

                // Writing ADC values.
        case 7:
                I2C_WriteByte(0x98); // Address the DAC
                break;

        case 8:
                I2C_WriteByte(0x10 + (DACChannel << 1)); // Select DAC Channel (0x10 = A, 0x12 = B, 0x14 = C)
                break;

        case 9:
                I2C_WriteByte(gyroAmplifierOffset.offsets[DACChannel]);
                break;

        case 10:
                I2C_WriteByte(0x80); // 2nd byte for all channels is 0x80
                break;

        case 11:
                I2C_Stop(TWI_STATE_MOTOR_TX);
                I2CTimeout = 10;
                // repeat case 7...10 until all DAC Channels are updated
                if (DACChannel < 2) {
                        DACChannel++; // jump to next channel
                        I2C_Start(TWI_STATE_GYRO_OFFSET_TX); // start transmission for next channel
                } else {
                        DACChannel = 0; // reset dac channel counter
                }
                break;

        default:
                I2C_Stop(TWI_STATE_MOTOR_TX);
                I2CTimeout = 10;
                motor_write = 0;
                motor_read = 0;
        }
}

extern void twi_diagnostics(void) {
        // Check connected BL-Ctrls
        uint8_t i;

        printf("\n\rFound BL-Ctrl: ");

        for (i = 0; i < MAX_MOTORS; i++) {
                motor[i].throttle = 0;
        }

        I2C_Start(TWI_STATE_MOTOR_TX);
        _delay_ms(2);

        motor_read = 0; // read the first I2C-Data

        for (i = 0; i < MAX_MOTORS; i++) {
                I2C_Start(TWI_STATE_MOTOR_TX);
                _delay_ms(2);
                if (motor[i].present)
                        printf("%d ",i+1);
        }

        for (i = 0; i < MAX_MOTORS; i++) {
                if (!motor[i].present && mixerMatrix.motor[i][MIX_THROTTLE] > 0)
                        printf("\n\r\n\r!! MISSING BL-CTRL: %d !!",i + 1);
                motor[i].error = 0;
        }
}