Help reading Serial EEPROM

[perkins]

Wow, first time to this group and already I'm looking for help with code.

My problem is that I can write a Floating point number to a serial EEPROM but cannot read back any reliable data that makes sense.

The hardware is part of a datalogger I'm working on and the serial EEPROM has been tested using inteter number and works fine- I believe that I can write a floating point number to the EEPROM but cannot read the hex values I expect to see.

I've distilled the code and I would be most appreciative if anyone can offer me inisghts to my problem.

Thanks, Al


PCM Version 2.693 (yes it is old!)


#include <16F877.H>

#fuses XT, NOPROTECT, NOPUT, NOWDT, NOBROWNOUT, NOLVP, NOCPD, NOWRT

/* EXTERNAL EEPROM ASSIGNMENTS */

#define EEPROM_ADDRESS long int
#define EEPROM_BYTE_SIZE 8192
#define EEPROM_SCL PIN_C3
#define EEPROM_SDA PIN_C4

#define hi(x) (*(&x+1))

#use delay ( clock=4000000 ) // clock 4 Mhz

#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7,parity=N)
#use i2c ( master, scl=EEPROM_SCL, sda=EEPROM_SDA )

void init_ext_eeprom ( void );
void write_ext_eeprom ( long int lngAddress, byte intData );
byte read_ext_eeprom ( long int lngAddress );

void WRITE_FLOAT_EXT_EEPROM(long int n,float fTempVal);

static float fTempVal;
static long int iTempVal;


void main ( void )
{
long int j,k;
float data;
init_ext_eeprom(); /* set SDA and SCL to float */

data=100.20; /* float data to start recording */
printf("\n\r");
for (k=0; k<3;k++)
{
printf("\n\rdata= %3.2f",data);
WRITE_FLOAT_EXT_EEPROM(k,data);
data=data+.2;
}

for (j=0; j<12;j++)
{
iTempVal=read_ext_eeprom(j);
}
}

/* EEPROM Routines */
void init_ext_eeprom ( void )
{
output_float ( EEPROM_SCL );
output_float ( EEPROM_SDA );
}

void write_ext_eeprom ( long int lngAddress, byte intData )

{
byte intDataR;
i2c_start();
i2c_write ( 0xa0 ); /* set up for writing address and data, chip address 000 */
i2c_write ( hi ( lngAddress ) ); /* write high address */
i2c_write ( lngAddress ); /* write low address */
i2c_write ( intData ); /* write data */
i2c_stop();
delay_ms ( 11 );
printf("\n\r\t\tWr %X",intData); /* print hex Write Data */
}



byte read_ext_eeprom ( long int lngAddress )
{
byte intData;

i2c_start();
i2c_write ( 0xa0 ); /* set up for writing address, chip address 000 */
i2c_write ( hi ( lngAddress ) ); /* write high address */
i2c_write ( lngAddress ); /* write low address */
i2c_start();
i2c_write ( 0xa1 ); /* set up for reading data, chip address 000 */
intData = i2c_read ( 0 ); /* read data */
i2c_stop();
delay_ms ( 11 );
printf("\n\r\t\tRd %X",intData); /* print hex Read Data */
return ( intData );
}


void WRITE_FLOAT_EXT_EEPROM(long int n,float fTempVal)

{
int i;

for (i=0;i<4;i++)
{
write_ext_eeprom(i+n,*(&fTempVal+i));
delay_ms(2);
}
}



Output Data on serial port:



data= 100.19
Wr 85
Wr 48
Wr 66
Wr 66

data= 100.39
Wr 85
Wr 48
Wr CC
Wr CC

data= 100.59
Wr 85
Wr 49
Wr 33
Wr 32

This is the serial data read - bears litlle resemblance to the written data

Rd 85
Rd 85
Rd 85 <- data 100.59?
Rd 49
Rd 33 <-
Rd 32
Rd 85
Rd 85
Rd 4B
Rd 38
Rd 4F

[mcafzap]

data=100.20; /* float data to start recording */
printf("\n\r");
for (k=0; k<3;k++)
{
printf("\n\rdata= %3.2f",data);
WRITE_FLOAT_EXT_EEPROM(k,data);
data=data+.2;
}

for (j=0; j<12;j++)
{
iTempVal=read_ext_eeprom(j);
}



I may be mistaken, but you seem to be incrementing your address within the EEPROM by one instead of 4 (since each float requires 4 bytes).

Steve

[Steve H.]

Check out these FAQ's...

http://www.ccsinfo.com/faq/?21

http://www.ccsinfo.com/faq/?24

Steve H.

[Guest]

Thank you very much Steve, I thought I had taken the 4 byte conversion into account but not so.

The program works and just in time- it's -23.4 degrees C outside and now I can start recording my temperature sensors.

Thanks again and Seasons Greetins.

Al