Subversion Repositories FlightCtrl

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

volatile uint8_t twi_state = TWI_STATE_IDLE;
volatile uint8_t dac_channel = 0;
volatile uint16_t I2CTimeout = 100;
volatile uint8_t DACValues[4];
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_IDLE;
    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_IDLE);
        TWCR = (1 << TWINT); // reset to original state incl. interrupt flag reset
        TWAMR = 0;
        TWAR = 0;
        TWDR = 0;
        TWSR = 0;
        TWBR = 0;
        I2C_init();
}

/****************************************
 * I2C ISR
 ****************************************/
ISR (TWI_vect)
{
        switch (twi_state) { // First i2c_start from SendMotorData()
        case 0: break;

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

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

        case 9:
            twi_state++;
                I2C_WriteByte(DACValues[DACChannel]);
                break;

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

        case 11:
            twi_state++;
                I2C_Stop(TWI_STATE_IDLE);
                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_IDLE);
                I2CTimeout = 10;
        }
}