i2c.c

lcd interface code for lpc214x series micro controllers

/**********************/
/*i2c.c				  */
/*Pierre Seguin		  */
/*[e-mail] */
/**********************/


#include "LPC210x.h"
#include "i2c.h"


#define I2C_ERROR 1                           // these are the values that are stored in i2c_status
#define I2C_OK 2                              // after reading or writing a byte and during an I2C operation
#define I2C_BUSY 0
#define EEPROM_ADDR	0xA0

unsigned char mask[] = {0xA8, 0x1F, 0x7F, 0x7F, 0x3F, 0x3F, 0x07, 0x1F,
                        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
			                              // mask values for registers


void InitI2C(void)
{
	
	I2C_I2CONCLR = 0xFF; 

	//  Set pinouts as scl and sda
	PINSEL0  |= 0x50;
	PINSEL0  &= (uint32_t)0xFFFFFF5F;
	
	I2C_I2SCLL=60;	//speed at 375Khz for a VPB Clock Divider  = 1
	I2C_I2SCLH=70;
	I2C_I2CONSET = 0x40; //Active Master Mode on I2C bus
}


void SendSlaveAdress(uint8_t Addr_S)
{	
	if(!(Addr_S&0x01)) //test if it's a master adress
	{
		//while(I2C_I2STAT!=0xF8);	
		I2C_I2CONSET = STA;
		while(I2C_I2STAT!=0x08); 	//Set and wait the start		
		I2C_I2DAT    = Addr_S; // Charge slave Address
		I2C_I2CONCLR = SIC|STAC; // Clear i2c interrupt bit to send the data    
		while(I2C_I2STAT!=0x18&&!(I2C_I2CONSET&SI));	//wait the ACK		
	}
	else			//it's a slave adress
	{
		I2C_I2CONSET = STA;
		I2C_I2CONCLR = SIC;
		while(I2C_I2STAT!=0x10&&!(I2C_I2CONSET&SI)); 	//Set and wait the start		
		I2C_I2DAT    = Addr_S; // Charge slave Address	
		I2C_I2CONCLR = SIC|STAC; // Clear i2c interrupt bit to send the data    
		while(I2C_I2STAT!=0x40&&!(I2C_I2CONSET&SI));	//wait the ACK
	}
}


uint8_t ReadOnI2C(void)
{
	I2C_I2CONCLR = SIC;							 //ACK from the master
	while(I2C_I2STAT!=0x50&&!(I2C_I2CONSET&SI)); //wait the data 
    // Read the data...  
	return I2C_I2DAT;
}



void WriteOnI2C(uint8_t Data)
{
	I2C_I2DAT    = Data; // Charge Data 
	I2C_I2CONCLR = SIC; // Clear i2c interrupt bit to send the data    	
	while(I2C_I2STAT!=0x28&&!(I2C_I2CONSET&SI));	//wait the ACK
}

uint8_t WriteRTC(uint8_t Addr,uint8_t Data)
{	
	SendSlaveAdress(EEPROM_ADDR);			//Send the Eeprom Adress	
	WriteOnI2C(Addr);	//Send Addr 
	WriteOnI2C(chartobcd(Data));						//Send Data 
	STOPI2C	
}


uint8_t ReadRTC(uint8_t Addr, uint8_t maskoff)
{
	uint8_t tmp;

	SendSlaveAdress(EEPROM_ADDR);//Send the Eeprom Adress	
	WriteOnI2C(Addr);	//Send Addr 
	SendSlaveAdress(EEPROM_ADDR|1);		
	tmp=ReadOnI2C();
	if (maskoff) tmp &= mask[Addr];  // mask result if required
    STOPI2C
//	return bcdtochar(tmp);        // convert to decimal and return result
	return tmp;
}






// function chartobcd
// converts a decimal value to the BCD equivalent
// decimal values must be stored in the Real Time Clock in BCD format
// passed is the decimal value to convert
// returned is the BCD equivalent
unsigned char chartobcd(unsigned char n)
{
  return ((n / 10) << 4) | (n % 10);  
}

// function bcdtochar
// converts a number in BCD format to the decimal equivalent
// decimal values must be stored in the Real Time Clock in BCD format
// passed is the BCD format value
// returned is the decimal equivalent
unsigned char bcdtochar(unsigned char bcdnum)
{
  return (bcdnum & 0x0f) + (bcdnum >> 4) * 10;
}