i2c.c

#include <xc.h>
#include "i2c.h"
//some of the code is adapted from https://www.microchip.com/content/dam/mchp/documents/MCU08/ApplicationNotes/ApplicationNotes/Getting_Started_With_I2C_Using_MSSP_onPIC18_90003281A.pdf

void I2C_2_Master_Init(void)
{
  //i2c config  
  SSP2CON1bits.SSPM= 0b1000;    // i2c master mode, Clock = FOSC/(4 * (SSPxADD + 1))
  SSP2CON1bits.SSPEN = 1;       //enable i2c, both pins must be configured as inputs
  SSP2ADD = (_XTAL_FREQ/(4*_I2C_CLOCK))-1; //Baud rate divider bits (in master mode)
  
  //pin configuration for i2c  
  TRISDbits.TRISD5 = 1;                   //Disable output driver
  TRISDbits.TRISD6 = 1;                   //Disable output driver
  ANSELDbits.ANSELD5=0;
  ANSELDbits.ANSELD6=0;
  SSP2DATPPS=0x1D;      //pin RD5
  SSP2CLKPPS=0x1E;      //pin RD6
  RD5PPS=0x1C;      // data output
  RD6PPS=0x1B;      //clock output
}

void I2C_2_Master_Idle(void)
{
  while ((SSP2STAT & 0x04) || (SSP2CON2 & 0x1F)); // wait until bus is idle
}                                   
void I2C_2_Master_Start(void)
{
  I2C_2_Master_Idle();              //always start with checking that the buffour is clear
  SSP2CON2bits.SEN = 1;             //Initiate start condition
}

void I2C_2_Master_RepStart(void)
{
  I2C_2_Master_Idle();
  SSP2CON2bits.RSEN = 1;           //Initiate repeated start condition
}

void I2C_2_Master_Stop()
{
  I2C_2_Master_Idle();
  SSP2CON2bits.PEN = 1;           //Initiate stop condition
}

void I2C_2_Master_Write(unsigned char data_byte)
{
  I2C_2_Master_Idle();
  SSP2BUF = data_byte;         //Write data to SSPBUF
}

unsigned char I2C_2_Master_Read(unsigned char ack)
{
  unsigned char tmp;
  I2C_2_Master_Idle();
  SSP2CON2bits.RCEN = 1;        // put the module into receive mode
  I2C_2_Master_Idle();
  tmp = SSP2BUF;                //Read data from SS2PBUF
  I2C_2_Master_Idle();
  SSP2CON2bits.ACKDT = !ack;     // 0 turns on acknowledge data bit
  SSP2CON2bits.ACKEN = 1;        //start acknowledge sequence
  return tmp;
}