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PIC18F4550 with 24LC16 EEPROM write and read only once

 
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mheber



Joined: 13 Jan 2012
Posts: 3
Location: Germany

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PIC18F4550 with 24LC16 EEPROM write and read only once
PostPosted: Fri Feb 10, 2012 3:51 am     Reply with quote

Hello @all, I have the problem, that I can write and read data in the EEPROM only once while my program is running. All subsequent writings and readings are ignored.
Code:

#include <18F4550.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use i2c(master, sda=PIN_C6, scl=PIN_C7, stream=EEP, force_sw)
#use i2c(master, sda=PIN_E1, scl=PIN_E2, stream=TMP, force_sw)

........

void main(void)
{
        char buf[64];
        int8 i;

        init_ext_eeprom();
        enable_interrupts(INT_SSP);
        enable_interrupts(GLOBAL);
   glcd_init(ON);
   delay_ms(200);
        glcd_fillScreen(off);  // Clear the display

       i = 0;
   while (true)
   {
            if (i == 8);
            i = 0;
           
            write_ext_eeprom(i, (i+1) * 8);
            sprintf (buf, "T=%Lu", GetTemp());
            glcd_rect (12, 8, 18*5, 8+7, yes, off);
            glcd_rect (12, 24, 18*5, 24+7, yes, off);
            glcd_text57 (0, 8, buf, 1, on);
            sprintf (buf, "M=%u", read_ext_eeprom(i));
            glcd_text57 (0, 24, buf, 1, on);
            i++;
            delay_ms(200);
   }
}

I've used the same EEPROM-Routines like in 2416.c only modified for using streams. As I tested with original 2416.c without the second I2C-Port the result was the same. I got only the result of the 1st write (8).
With hard coding the read address I found out, that the other addresses are not written. Only the first write and read occurs all subsequent operations are ignored. I have a 24LC16B connected to the 18F4550 with 2.2k pull up resistors. Do anyone know about this strange effect?
Thanks in advance.
Michael
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Fri Feb 10, 2012 2:49 pm     Reply with quote

Post a short test program that shows the problem. Cut out all the glcd
stuff. Put in a #use rs232() statement and use printf to display the
results. Then tell us what you saw.

Also post your CCS compiler version.
mheber



Joined: 13 Jan 2012
Posts: 3
Location: Germany

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PostPosted: Sun Feb 12, 2012 3:57 am     Reply with quote

Hello PCM programmer,
thanks for your help. I don't know why but now every thing works as expected. I guess a bad connection on the breadboard. I use the actual compiler version 4.129. BTW there is a error in the 2416.c:
"#define EEPROM_SIZE 1024" is wrong because it's a 16k-bit (2048x8)
EEPROM.

Best Regards
Michael
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