what is sda setup time violation in EEPROM interfacing with PIC18F452

[billy2tom]

i simulated the pgm using c18 compiler. when i simulate in proteus i am getting
error as sda setup time error. Can anyone help me plz...


#pragma config OSC=HS, OSCS = OFF
#pragma config PWRT = OFF, BOR = ON, BORV = 45
#pragma config WDT = OFF
#pragma config DEBUG = OFF, LVP = OFF, STVR = OFF

#include<p18f452.h>
#include<usart.h>
#include<delays.h>
#define SCL PORTCbits.RC3
#define SDA PORTCbits.RC4

int Transmit(unsigned char data);
void Transmit_gui(void);
int Start(void);
void Stop(void);
void Read24c64B(unsigned char RomAddress);
void Read_eeprom(unsigned int e_add);
void Ack(void);
void NoAck(void);
void init();
void hex_ascii(unsigned char var);
void display_USART(unsigned char disp);
void New_Write_eeprom(unsigned char d);
unsigned char Read8Bit(void);
void delay(unsigned int itime);

unsigned char buf[10] = {1,2,3,4,5,6,7,8,9,10};
unsigned char a,d,indic,j,ReadData,s=0;
unsigned int eeprom_data,data_msb,data_lsb,ia,Gui[16],Gui_Inc,i,k,Gui_Buffer,Gui_Buff[10],Msb,Lsb,Var;
unsigned int device_add,Dt,Data;
unsigned int lsb_add=10;
unsigned int add_msb = 0,add_lsb = 0,x,b,c, AS_TEMP1,AS_TEMP2,var;


void main()
{
TRISCbits.TRISC3=0;
TRISCbits.TRISC7=1;
OpenUSART( USART_TX_INT_OFF & USART_RX_INT_OFF & USART_ASYNCH_MODE& USART_EIGHT_BIT & USART_CONT_RX & USART_BRGH_HIGH, 25 );
Delay10KTCYx(100);
while(1)
{
New_Write_eeprom();
delay(10);

Read24c64B(s);
delay(10);
s++;
display_USART(ReadData);
putcUSART(' ');
}

}

int Transmit(unsigned char data)
{
unsigned char b=0,c=0;
unsigned int a;
a = 0x80;
for(b=0;b<8;b++)
{ c = 0;
c = data & a;
if(c==0)
SDA=0;
else
SDA=1;
SCL=1;
for(d=0;d<8;d++);
SCL=0;
a = a>>1;
}
SCL=0;
return 0;
}



void New_Write_eeprom(unsigned char d)
{
Start();

Transmit(0xA0);
Ack();

Transmit(0x00);
Ack();

Transmit(0x00);
Ack();

Transmit('d');
Ack();

Stop();
}

void Read_eeprom(unsigned int e_add)
{
lsb_add = e_add & 0xFF;
device_add = (e_add / (0x100));
Read24c64B(lsb_add);
}
void Read24c64B(unsigned char RomAddress)
{
Start();

Transmit(0xA0);
Ack();

Transmit(0x00);
Ack();

Transmit(RomAddress);
Ack();

Start();
Transmit(0xA1);
Ack();

ReadData=Read8Bit();
NoAck();

Stop();
}

int Start(void)
{
SDA=1;
SCL=1;
for(a=0; a<10;a++);
SDA=0;
for(a=0; a<10;a++);
SCL=0;
return 0;
}

void Stop(void)
{
SDA=0;
SCL=1;
for(a=0; a<50;a++);
SDA=1;
for(a=0; a<50;a++);
}

void Ack(void)
{
TRISC |= 0x10;
SCL=1;
if(SDA)
indic=1;
else
indic=0;
SCL=0;
TRISC &= 0xEF;
}

void NoAck(void)
{
SDA=1;
SCL=1;
for(a=0; a<10;a++);
}

unsigned char Read8Bit(void)
{
unsigned char i,rbyte=0;
SDA=1;
TRISC |= 0x10; //setting SDA as input mode
for(i=1;i<=8;i++)
{
SCL=1;
rbyte<<=1;
if(SDA)
rbyte|=0x01;
for(d=0;d<10;d++); //100
SCL=0;
}
TRISC &= 0xEF; //setting SDA back to output mode
return(rbyte);
}

void hex_ascii(unsigned char var)
{

AS_TEMP1 = var & 0x0F;
AS_TEMP1=(AS_TEMP1>=0xa?AS_TEMP1+0x37:AS_TEMP1+0x30);
AS_TEMP2=(var & 0xF0)>>4;
AS_TEMP2=(AS_TEMP2>=0xa?AS_TEMP2+0x37:AS_TEMP2+0x30);
}
void display_USART(unsigned char disp)
{

hex_ascii(disp);
delay(10);
putcUSART(AS_TEMP2);
delay(10);
putcUSART(AS_TEMP1);
delay(10);
AS_TEMP2=AS_TEMP1=0;

}

void delay(unsigned int itime)
{
int i,j;
for(i=0;i<itime;i++)
for(j=0;j<2;j++);
}

 

[Militoy]

I’m not an expert programmer – and I haven’t taken time to look through your code (additional comments might make it easier) – but I2C functions typically employ a small delay routine in between SDA and SCL changes to give a clear sequence on the I2C bus – usually just a simple subroutine call and return as:

Void i2c_dly (void) // i2c bus clear delay
{
}

So a start bit sequence would look something like:

Int Start (void)
{
SDA = 1; // i2c start bit sequence
i2c_dly() ;
SCL = 1;
For(a=0 ; a<10; a++);
i2c_dly() ;
SDA = 0;
For(a=0 ; a<10; a++);
i2c_dly() ;
SCL = 0;
Return 0;
}

If you’re having setup time errors you can try clearing the bus between changes – and see if your simulation improves. If not – nothing lost.