/home/daqweb/fgddaq/c8051/Protocols/I2C_handler.c File Reference

#include "../asum/mscbemb.h"
#include "I2C_handler.h"

Functions
void	I2C_Clear (void)
void	I2C_Start (void)
void	I2C_Stop (void)
unsigned char	I2C_WriteByte (unsigned char datByte, unsigned char flag)
unsigned char	I2C_ReadByte (bit flag)
void	I2C_ClockOnce (void)
Variables
sbit	I2C_SDA = MSCB_I2C_SDA
sbit	I2C_SCL = MSCB_I2C_SCL

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Function Documentation

void I2C_Clear

(

void

)

{
        //Bus freeTime between Stop and Start condition
        I2C_SDA = 1;
        I2C_SCL = 1;
        delay_us(I2C_T_BUF); 
}

void I2C_ClockOnce

(

void

)

{
        I2C_SCL = 1;
        delay_us(I2C_T_HIGH);
        I2C_SCL = 0;
        delay_us(I2C_T_LOW);    
}

unsigned char I2C_ReadByte

(

bit

flag

)

{
        char i = 0;
        char dataRead = 0x00;

        for(i = 7; i >= 0; i--)
        {
                dataRead |= ((unsigned char) I2C_SDA) << i;
                I2C_ClockOnce();
        }

        //send ACK / NACK
        if(flag == ACK)
        {
                I2C_SDA = 0;
        }
        else if(flag == I2C_NACK)
        {
                I2C_SDA = 1;
        }
        I2C_ClockOnce();

        return dataRead;
}

void I2C_Start

(

void

)

{
        //Bus freeTime between Stop and Start condition (Clearing function)
        I2C_Clear();

        //Start condition: I2C_SDA goes from HIGH to LOW while I2C_SCL is HIGH
        delay_us(I2C_SU_STA);
        I2C_SDA = 0;
        delay_us(I2C_HD_STA);
        I2C_SCL = 0;    
}

void I2C_Stop

(

void

)

{
        //Stop condition: I2C_SDA goes from LOW to HIGH while I2C_SCL is HIGH
        I2C_SCL = 1;
        delay_us(I2C_SU_STO);
        I2C_SDA = 1;
}

unsigned char I2C_WriteByte	(	unsigned char	datByte,
		unsigned char	flag
	)

{
        char i = 0;
        unsigned char toBeSent = 0;

        if(flag == I2C_WRITE_FLAG)
        {
                toBeSent = (datByte << 1) & 0xFE;
        }
        else if(flag == I2C_READ_FLAG)
        {
                toBeSent = (datByte << 1) | 0x01;
        }
        else
        {
                toBeSent = datByte;
        }
        for(i = 7; i >= 0; i--)
        {
                I2C_SDA = (toBeSent >> i) & 0x01;
                delay_us(1); //SU;DAT
                I2C_ClockOnce();
        }

        if(I2C_SDA == 1)
        {
                I2C_ClockOnce();
                return I2C_ACK;
        }
        else if(I2C_SDA == 0)
        {
                I2C_ClockOnce();
                return I2C_NACK;
        }
        else
        {
                I2C_ClockOnce();
                return I2C_WRITE_ERROR;
        }
}

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Variable Documentation

sbit I2C_SCL = MSCB_I2C_SCL

sbit I2C_SDA = MSCB_I2C_SDA

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