CODEWITHSUNDEEP
microcontrollerpiceeprom
PicFan57
PicFan57

Reputation: 1

PIC I2C communication with external EEPROM

I am new to PIC. I know there are lot of posts in this forum on I2C and I have tried all the methods given but still doesn't solve my problem. I am using pic16f1516 and an external EEPROM CAT24C04TDI to store some data. I have used 4k7 ohm resistors for pull up and my code is :

void I2CWrite(void); 
void WaitMSSP(void);
void I2CRead(void);
void i2c_init(void);
//void _delay_ms(unsigned int);
void main()
{ 
_delay_ms(100); // Give delay for power up
i2c_init(); // Initialize I2C
_delay_ms(20); 
I2CWrite(); // Sends the data to I2C EEPROM
_delay_ms(50);
while(1)
{
I2CRead(); // Read back the data?s
TXREG='\n';
while(TXIF==0); 
TXREG='\r'; 
_delay_ms(500);
}
} 
void I2CWrite()
{
SSPCON2bits.SEN=1;
WaitMSSP(); // wait for the operation to be finished
SSPBUF=0xa0;//Send Slave address write command
WaitMSSP();
SSPBUF=0x00; // Send the starting address to write
WaitMSSP(); 
SSPBUF=0x34; // rough data to be written
WaitMSSP();
}
PEN=1; // Send stop bit
WaitMSSP(); 
}
void I2CRead()
{
SEN=1; //Send start bit
WaitMSSP(); //wait for the operation to be finished
SSPBUF=0xa0;//Send Slave address write command
WaitMSSP(); 
SSPBUF=0x00; // Send the starting address to write
WaitMSSP(); 
RSEN=1; // Send re-start bit
WaitMSSP();
SSPBUF=0xa1; // Slave address read command
WaitMSSP();
RCEN=1; // Enable receive
WaitMSSP(); 
ACKDT=1; // Acknowledge data 1: NACK, 0: ACK
ACKEN=1; // Enable ACK to send
PEN=1; // Stop condition
WaitMSSP();
putch(SSPBUF); // Send the received data to PC
_delay_ms(30); 
}
PEN=1;
WaitMSSP();
}
void WaitMSSP()
{
while(!SSPIF); // while SSPIF=0 stay here else exit the loop
SSPIF=0; // operation completed clear the flag
}
void i2c_init()
{
TRISCbits.TRISC3=1; // Set up I2C lines by setting as input
TRISCbits.TRISC4=1;
SSPCON1 = 0b00101000; 
// SSPADD=(FOSC / (4 * I2C_FREQ)) - 1; //clock 100khz
SSPADD = 0x18 ; //clock 100khz
SSPSTAT=80; // Slew rate control disabled

PIR1bits.SSPIF = 0; // Clear MSSP interrupt request flag
PIE1bits.SSPIE = 1; // Enable MSSP interrupt enable bit

}

When I connect it to oscilloscope, nothing happens at SDA and SCL ports after sending SEN=1. Please help me with this problem. I am stuck with this since long time.

Upvotes: 0

Views: 1364

Answers (1)

Weather Vane
Weather Vane

Reputation: 34583

SSPIFis not a register: the data sheet shows it to be bit 3 in register PIR1 so instead of the line

while(!SSPIF); // while SSPIF=0 stay here else exit the loop
SSPIF = 0;     // operation completed clear the flag

this means you should to test and clear it with 

while ((PIR1 & 0x08) == 0);
PIR1 = 0;

The assembler instruction to clear the status is

BCF PIR1,SSPIF ;I2C done, clear flag

and more detail of the code is in this forum also please read the data sheet for more information.

Upvotes: 0

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