I2C Slave

#include <xc.h>
#include "Libraries/Global/conf.h"
#include "Libraries/I2C/I2C.h"
#include "Libraries/Relais/Relais.h"


struct Relais _relais;
    char data = 0;
    char data2 = 0;


void System_INIT();
void OSC_INIT();
void Pinning_INIT();

/*
 *
 * Main Function
 *
 */

void main(void) {
    System_INIT();                              //Call the System Initialisation function

    while(1)
    {
        Relais_Turn_ON_OFF(_relais.value);      //Call Relais function, turns on/off relais
        _data = Relais_Validate_State();
    }
    return;
}

/*
 * Name: ISR
 * Function: Interrupt function, call all other interupt functions
 * Input: None
 * Output: None
 */

void __interrupt() ISR()
{
    data = I2C_Slave_Read(&data2);          //call the interrupt for I2C bus
    __delay_us(1);                          //dummy delay
    if (data2)                              //check if received info is data or address
    {
        _relais.value = data;               //transfer data to relais struct
    }
}

/*
 *
 * Init Functions
 *
 */

void System_INIT()
{
    OSC_INIT();                             //Init clock
    Pinning_INIT();                         //init Pinning
    Relais_INIT();                          //init relais pinning
    _relais.value = 0xff;                   //initialize relais values (should be 0, but test board has inverted logic)
    I2C_Init(I2C_SLAVE, 0x2A);              //Init I2C
}

void OSC_INIT()
{
    OSCCON1bits.NOSC = 0b110;               // = HFINTOSC
    OSCCON1bits.NDIV = 0b0000;              // Clock divider = 1
    OSCFRQbits.HFFRQ = 0b1000;              // HFINTOSC Frequency selection bits: 64 Nominal Freq (MHz)
    OSCENbits.HFOEN = 0b1;                  // HFINTOSC is explicitly enabled, operating as specified by OSCFRQ
}

void Pinning_INIT()
{
    _GPIO_LOW(IO_LED);                      //turn test led low
    _GPIO_OUT(IO_LED);                      //enable output for led
    _GPIO_DIGITAL(IO_LED);                  //set output to digital

}

void I2C_Init(uchar master, uchar clock_speed_addres)
{
    PPSLOCK = 0x55;
    PPSLOCK = 0xAA;
    PPSLOCKbits.PPSLOCKED = 0;
    SSP1CLKPPS = 0x13;      // MSSP1:SCL1->RC3;
    SSP1DATPPS = 0x14;      // MSSP1:SDA1->RC4;
    RC3PPS = 0x0F;          // RC3->MSSP1:SCL1;
    RC4PPS = 0x10;          // RC4->MSSP1:SDA1;

    PPSLOCK = 0x55;
    PPSLOCK = 0xAA;
    PPSLOCKbits.PPSLOCKED = 1;
    _GPIO_DIGITAL(IO_SCL);          //Make digital
    _GPIO_DIGITAL(IO_SDA);

    _GPIO_LOW(IO_SCL);              // make low
    _GPIO_LOW(IO_SDA);
    _GPIO_IN(IO_SCL);               //Make tristate
    _GPIO_IN(IO_SDA);
    TRISCbits.TRISC3 = 0b1;
    TRISCbits.TRISC4 = 0b1;
    // Analog Select Register
    //  1 Digital Input buffers are disabled
    //  0 ST and TTL input buffers are enabled
    ANSELCbits.ANSELC3 = 0b0;
    ANSELCbits.ANSELC4 = 0b0;
    // Input Level Control Register
    // 1 ST input used for port reads and interrupt-on-change
    // 0 TTL input used for port reads and interrupt-on-change
    INLVLCbits.INLVLC3 = 0b1;
    INLVLCbits.INLVLC4 = 0b1;
    // Slew Rate Control
    //  1 Port pin slew rate is limited
    //  0 Port pin slew at maximum rate
    SLRCONCbits.SLRC3 = 0b0;
    SLRCONCbits.SLRC4 = 0b0;

#ifdef testing
    WPUCbits.WPUC3 = 0b1;
    WPUCbits.WPUC4 = 0b1;
#endif

    if (master)
    {
        SSP1CON1 = 0b00101000;            //SSP Module as Master
        SSP1CON2 = 0;
        SSP1ADD = (_XTAL_FREQ/(4*clock_speed_addres))-1; //Setting Clock Speed
        SSP1STAT = 0;
    }
    else
    {
        SSP1STAT = 0x80;
        SSP1ADD = clock_speed_addres<<1; //Setting address
        SSP1CON1 = 0x36;    //As a slave device
        SSP1CON2 = 0x01;
        SSP1CON3 = 0b00000110;
        GIE = 1;          //Global interrupt enable
        PEIE = 1;         //Peripheral interrupt enable
        SSP1IF = 0;        //Clear interrupt flag
        SSP1IE = 1;        //Synchronous serial port interrupt enable
        SSP1MSK = 0xFF;
    }
}

void I2C_Master_Wait()
{
  while ((SSP1STAT & 0x04) || (SSP1CON2 & 0x1F)); //Transmit is in progress
}

void I2C_Master_Start()
{
  I2C_Master_Wait();
  SEN1 = 1;             //Initiate start condition
}

void I2C_Master_RepeatedStart()
{
  I2C_Master_Wait();
  RSEN1 = 1;           //Initiate repeated start condition
}

void I2C_Master_Stop()
{
  I2C_Master_Wait();
  PEN1 = 1;           //Initiate stop condition
}

char I2C_Master_Write(unsigned data_byte)
{
  I2C_Master_Wait();
  SSP1BUF = data_byte;         //Write data to SSPBUF
  I2C_Master_Wait();
  return ACKSTAT1;
}

uchar I2C_Master_Read(uchar ACK)
{
  unsigned short retVal;
  I2C_Master_Wait();
  RCEN1 = 1;
  I2C_Master_Wait();
  retVal = SSP1BUF;      //Read data from SSPBUF
  I2C_Master_Wait();
  ACKDT1 = (ACK)?0:1;    //Acknowledge bit
  ACKEN1 = 1;          //Acknowledge sequence
  return retVal;
}

void I2C_Master_Write_Byte(char address, char data)
{
    I2C_Master_Start();
    I2C_Master_Write(address);
    I2C_Master_Write(data);
    I2C_Master_Stop();
}

char I2C_Slave_Read(char *data)
{
    GIE = 0;
    char retVal = 0;
  if(SSP1IF == 1)
  {
    //CKP1 = 0;
      data[0]=0;

    if ((SSPOV1) || (WCOL1)) //If overflow or collision
    {
      retVal = SSP1BUF; // Read the previous value to clear the buffer
      SSPOV1 = 0; // Clear the overflow flag
      WCOL1 = 0; // Clear the collision bit
      CKP1 = 1;
    }

  if(!SSP1STATbits.D_nA && !SSP1STATbits.R_nW) //If last byte was Address + Write
  {
    retVal = SSP1BUF;
    CKP1 = 1;
    while(BF1);
    //while(!BF1);

    //PORTD = ~SSP1BUF;
    //CKP1 = 1;
  }
  else if(SSP1STATbits.D_nA && !SSP1STATbits.R_nW)
  {
    retVal = ~SSP1BUF;
    CKP1 = 1;
    data[0] = 1;
  }
  else if(!SSP1STATbits.D_nA && SSP1STATbits.R_nW) //If last byte was Address + Read
  {
    SSP1IF = 0;
    retVal = SSP1BUF;
    while(BF1);
//    BF1 = 0;
    SSP1BUF = _data ;
    CKP1 = 1;
    //while(!SSP1IF);
    SSP1IF = 0;
    //while(SSP1STATbits.BF);
    SSP1IF = 0;
    if(ACKSTAT1)
    {
        SSP1BUF = _data ;
        CKP1 = 1;
        //while(!SSP1IF);
        SSP1IF = 0;
    }
    CKP1 = 1;
    SSP1IF = 0;
  }

  SSP1IF = 0;
  }
    SSP1IF  =0;
    GIE = 1;
    return retVal;
}