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/*#######################################################################################
MK3Mag 3D-Magnet sensor
!!! THIS IS NOT FREE SOFTWARE !!!
#######################################################################################*/

// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Copyright (c) 05.2008 Holger Buss
// + Thanks to Ilja Fähnrich (P_Latzhalter)
// + Nur für den privaten Gebrauch
// + www.MikroKopter.com
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Die Portierung der Software (oder Teile davon) auf andere Systeme (ausser der Hardware von www.mikrokopter.de) ist nur
// + mit unserer Zustimmung zulässig
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Es gilt für das gesamte Projekt (Hardware, Software, Binärfiles, Sourcecode und Dokumentation),
// + dass eine Nutzung (auch auszugsweise) nur für den privaten (nicht-kommerziellen) Gebrauch zulässig ist.
// + AUSNAHME: Ein bei www.mikrokopter.de erworbener vorbestückter MK3Mag darf als Baugruppe auch in kommerziellen Systemen verbaut werden
// + Im Zweifelsfall bitte anfragen bei: info@mikrokopter.de
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Werden Teile des Quellcodes (mit oder ohne Modifikation) weiterverwendet oder veröffentlicht,
// + unterliegen sie auch diesen Nutzungsbedingungen und diese Nutzungsbedingungen incl. Copyright müssen dann beiliegen
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Sollte die Software (auch auszugesweise) oder sonstige Informationen des MikroKopter-Projekts
// + auf anderen Webseiten oder sonstigen Medien veröffentlicht werden, muss unsere Webseite "http://www.mikrokopter.de"
// + eindeutig als Ursprung verlinkt werden
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Keine Gewähr auf Fehlerfreiheit, Vollständigkeit oder Funktion
// + Benutzung auf eigene Gefahr
// + Wir übernehmen keinerlei Haftung für direkte oder indirekte Personen- oder Sachschäden
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Die Funktion printf_P() unterliegt ihrer eigenen Lizenz und ist hiervon nicht betroffen
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// + Redistributions of source code (with or without modifications) must retain the above copyright notice,
// + this list of conditions and the following disclaimer.
// +   * PORTING this software (or parts of it) to systems (other than hardware from www.mikrokopter.de) is NOT allowed
// +   * Neither the name of the copyright holders nor the names of contributors may be used to endorse or promote products derived
// +     from this software without specific prior written permission.
// +   * The use of this project (hardware, software, binary files, sources and documentation) is only permittet
// +     for non-commercial use (directly or indirectly)
// +     Commercial use (for excample: selling of MikroKopters, selling of PCBs, assembly, ...) is only permitted
// +     with our written permission
// +     Exception: A preassembled MK3Mag, purchased from www.mikrokopter.de may be used as a part of commercial systems
// +     In case of doubt please contact: info@MikroKopter.de
// +   * If sources or documentations are redistributet on other webpages, our webpage (http://www.MikroKopter.de) must be
// +     clearly linked as origin
// +  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// +  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// +  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// +  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// +  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// +  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// +  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// +  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// +  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// +  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// +  POSSIBILITY OF SUCH DAMAGE.
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/twi.h>
#include "twislave.h"
#include "uart.h"
#include "main.h"
#include "timer0.h"

#define TWI_BUS_ERR_1   0x00
#define TWI_BUS_ERR_2   0xF8

// Status Slave RX Mode
#define SR_SLA_ACK      0x60
#define SR_LOST_ACK     0x68
#define SR_GEN_CALL_ACK 0x70
#define GEN_LOST_ACK    0x78
#define SR_PREV_ACK     0x80
#define SR_PREV_NACK    0x88
#define GEN_PREV_ACK    0x90
#define GEN_PREV_NACK   0x98
#define STOP_CONDITION  0xA0
#define REPEATED_START  0xA0

// Status Slave TX mode
#define SW_SLA_ACK      0xA8
#define SW_LOST_ACK     0xB0
#define SW_DATA_ACK     0xB8
#define SW_DATA_NACK    0xC0
#define SW_LAST_ACK     0xC8


uint8_t I2C_RxBufferSize, I2C_TxBufferSize;
uint8_t *I2C_TxBuffer, *I2C_RxBuffer;
uint8_t Tx_Idx = 0, Rx_Idx = 0, I2C_Direction;
uint8_t I2C_Command;


I2C_Heading_t       I2C_Heading;
I2C_WriteAttitude_t I2C_WriteAttitude;
I2C_Mag_t           I2C_Mag;
I2C_EEPROM_t        I2C_ReadEEPROM, I2C_WriteEEPROM;
I2C_Version_t       I2C_Version;
I2C_WriteCal_t      I2C_WriteCal;


void I2C_Init(void)
{
        uint8_t sreg = SREG;
        cli();

        //SPI SCK/SCL and  MISO/SDA are at put together on the same connector pin in the schematic

        // set PB4 (SCK) and PB5 (MISO) as input pull up
        DDRB &= ~((1<<DDB4)|(1<<DDB5));
        PORTB |= ((1<<PORTB4)|(1<<PORTB5));

        // set PC4 (SDA) and PC5 (SCL) as input pull up
        DDRC &= ~((1<<DDC4)|(1<<DDC5));
        PORTC |= ((1<<PORTC4)|(1<<PORTC5));

         // set own address
    TWAR = I2C_SLAVE_ADDRESS; // set own address
        // TWI Control Register
        // clear TWI interrupt flag (TWINT=1)
        // enable TWI Acknowledge Bit (TWEA = 1)
        // disable TWI START Condition Bit (TWSTA = 0), SLAVE
        // disable TWI STOP Condition Bit (TWSTO = 0), SLAVE
        // disable TWI Write Collision Flag (TWWC = 0)
        // enable i2c (TWEN = 1)
        // enable TWI Interrupt (TWIE = 1)
    TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWIE) | (1<<TWEA);
        // update version info
        I2C_Version.Major = VERSION_MAJOR;
        I2C_Version.Minor = VERSION_MINOR;
        I2C_Version.Compatible = I2C_PROTOCOL_COMP;

        SREG = sreg;
}



#define TWCR_ACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC)

ISR (TWI_vect)
{
        // check event
        switch (TWSR & 0xF8)
        {
        case SR_SLA_ACK:
            Rx_Idx = 0;
                        TWCR_ACK;
            return;

        case SR_PREV_ACK: // data byte received

                        if (Rx_Idx  == 0)
                        {
                                I2C_Command = TWDR;

                                switch(I2C_Command)
                                {
                                        case I2C_CMD_VERSION:
                                                I2C_TxBuffer = (uint8_t *)&I2C_Version;
                                                I2C_TxBufferSize = sizeof(I2C_Version);
                                                I2C_RxBufferSize = 0;
                                                break;

                                        case I2C_CMD_WRITE_EEPROM:
                                                I2C_TxBufferSize = 0;
                                                I2C_RxBuffer = (uint8_t *)&I2C_WriteEEPROM;
                                                I2C_RxBufferSize = sizeof(I2C_WriteEEPROM);
                                                break;

                                        case I2C_CMD_WRITE_CAL:
                                                I2C_TxBufferSize = 0;
                                                I2C_RxBuffer = (uint8_t *)&I2C_WriteCal;
                                                I2C_RxBufferSize = sizeof(I2C_WriteCal);
                                                break;

                                        case I2C_CMD_READ_EEPROM:
                                                I2C_TxBuffer = (uint8_t *)&I2C_ReadEEPROM.Content;
                                                I2C_TxBufferSize = 2;
                                                I2C_RxBuffer = (uint8_t *)&I2C_ReadEEPROM;
                                                I2C_RxBufferSize = 1;
                                                break;

                                        case I2C_CMD_READ_MAG:
                                                I2C_TxBuffer = (uint8_t *)&I2C_Mag;
                                                I2C_TxBufferSize = sizeof(I2C_Mag);
                                                I2C_RxBufferSize = 0;

                                                I2C_Mag.MagX = MagnetX;
                                                I2C_Mag.MagY = MagnetY;
                                                I2C_Mag.MagZ = MagnetZ;
                                                break;

                                        case I2C_CMD_READ_HEADING:
                                                I2C_TxBuffer = (uint8_t *)&I2C_Heading;
                                                I2C_TxBufferSize = sizeof(I2C_Heading);
                                                I2C_RxBuffer =  (uint8_t *)&I2C_WriteAttitude;
                                                I2C_RxBufferSize = sizeof(I2C_WriteAttitude);
                                                // update heading from global variable
                                                I2C_Heading.Heading = Heading;
                                                // copy current attitude from I2C rx buffer to uart rx buffer (this is used for the calulation of the heading)
                                                ExternData.Attitude[NICK] = I2C_WriteAttitude.Nick;
                                                ExternData.Attitude[ROLL] = I2C_WriteAttitude.Roll;
                                                break;
                                }
                        }
                        else // Rx_Idx  != 0
                        {
                                // fill receiver buffer
                                if ((Rx_Idx - 1) < I2C_RxBufferSize) I2C_RxBuffer[Rx_Idx - 1] = TWDR;
                        }
                        // next byte
                        Rx_Idx++;

            I2C_Timeout = 500;
                        TWCR_ACK; // send acknowledge
            return;

        case SW_SLA_ACK: // slave transmitter selected
                // reset position in tx buffer
            Tx_Idx = 0;
            // write first bte o tx buffer to the twi data register
                        if (I2C_TxBufferSize > 0) TWDR = I2C_TxBuffer[Tx_Idx++];
                        // send acknowledge
            TWCR_ACK;
            return;

                case SW_DATA_ACK: // send data byte
                        // put next byte from tx buffer to twi data register
            if (Tx_Idx < I2C_TxBufferSize) TWDR = I2C_TxBuffer[Tx_Idx++];
                        else TWDR = 0x00;
                        TWCR_ACK; // send acknowledge
            return;

        // clear Bus-Error
        case TWI_BUS_ERR_2:
            TWCR |=(1<<TWSTO) | (1<<TWINT);
        // clear Bus-Error
        case TWI_BUS_ERR_1:
            TWCR |=(1<<TWSTO) | (1<<TWINT);
        }
        // clear interrupt flag (TWINT = 1)
        // enable TWI Acknowledge Bit (TWEA = 1)
        // enable TWI (TWEN = 1)
        // enable TWI interrpt (TWIE = 1)
    TWCR = (1<<TWEA) | (1<<TWINT) | (1<<TWEN) | (1<<TWIE); // TWI Reset
}