[SOLVED] Internal EEPROM for PIC16F876A using HI tech compiler

[Nikunj Tanna]

Hello,

I am trying to save some bytes of data into the internal EEPROM of PIC16F876A, but i am not getting the things done. I am using Hi- Tech C compiler and it has example code for EEPROM in pic.h.. I am using that, i write single byte in EEPROM and read the same and compares it but i am not getting right values. Then I tried to make my own functions but those are also not working. I am pasting my testing code and my functions. Kindly check it out and help me..

// Testing code-------------------------------------------------

#include <pic.h>
#include <htc.h>
#include <stdio.h>
#include <eeprom_routines.h>
#include "delay.h"
#include "always.h"
//void eeprom_write(unsigned char, unsigned char);
//unsigned char eeprom_read(unsigned char);
void main (void)
{
unsigned char u;
TRISC0 = 0;
TRISC1 = 0;
TRISC2 = 0;
PORTC = 0x00;
RC0 = 0;
RC1 = 0;
RC2 = 0;
eeprom_write(0x10,0x34);
DelayS(5);
u = eeprom_read(0x10);
while(1)
{
if(u == 0x34)
{
RC0 = 1;RC1 = 0;RC2 = 1;
DelayS(1);
RC0 = 0;RC1 = 1;RC2 = 0;
DelayS(1);
}
RC0 = 1;RC1 = 1;RC2 = 1;
DelayS(1);
RC0 = 0;RC1 = 0;RC2 = 0;
DelayS(1);
}
}

///////////// my functions to use with same above testing code../////////

void eeprom_write(unsigned char add, unsigned char data)
{
GIE = 0;
EEPGD = 0;
WREN = 1;
EEADR = add;
EEDATA = data;
EECON2 = 0X55;
EECON2 = 0XAA;
WR = 1;
while(WR) continue;
WREN = 0;
}

unsigned char eeprom_read(unsigned char add)
{
EEPGD = 0;
EEADR = add;
RD = 1;
while(RD)continue;
return EEDATA;
}


What can be the reason for not working in any of the two ways ? please tell me..

NIKS

 

[Nikunj Tanna]

Hey,

No one to reply..!!!!

My read function works ok and reads 0xff on every location but when i try to call write function, the WREER bit gets high and the write operation gets interrupted...

Atleast answer me now, I am stopped...

NIKS

 

[ckshivaram]

#pragma config OSC = HS // 20MHz Crystal, (HS oscillator)
#pragma config WDT = OFF // watch dog timer off
#pragma config LVP = OFF // Low voltage program off

Please post your initial configurations like i have told above

 

[Nikunj Tanna]

I have already configuration bits like this.
I am using 16MHz crystal so I already use HS oscillator, Watchdog timer off, Low voltage programming off..
Still I am writing the same in code now and testing again, I have set those in configuration bits...

Thank you and please tell me if any other changes...

NIKS

---------- Post added at 17:59 ---------- Previous post was at 17:46 ----------

Sorry, I misunderstood the reply of yours..

my initial configuration bits are 1F7A..
it means
HS oscillator
WDT disabled
PWRT disabled
RB3 is digital i/o, HV on MCLR must be used for programming
DATA EEPROM code protection off
Flash program write protection off
Code protect on

NIKS

 

[luben111]

Hi
HiTech has nice special feature to define a variable into EEPROM - when doing reading and writing to this variable the compiler will take care for the EEPROM. Because I didn't work for long time with HiTech as I remember it was something like __eeprom uchar myVar @ MyAddress;
I would suggest you check the HiTech manual for more information

 

[Nikunj Tanna]

Hi,

Yes, I heard about that.. It's something called HI Tech eeprom qualifier.. But i don't know how to use it and if my current version is supporting it or not ? If any one knows that way to write in EEPROM, it will also be helpful to me.. I have evaluation version of Hi tech PRO 9.60PL5.

Thank you
NIKS

 

[ckshivaram]

Its not mandatory to use it. the sample code works fine in simulator

 

[Nikunj Tanna]

But sir,

It doesn't get run as you can see in my first post. I blinked three pins of Port C on successful write and read of single byte.
which doesn't happen.. when I read it, it gives 0xff..

Can you tell me where i made mistake in my code ?
or any fuse bit problems ?
Is it necessary to monitor WREER bit? I checked it just after calling write function and it's high.
Where it should be checked ?
is it the problem with my code ?

Thank you
NIKS

 

[ckshivaram]

Microchip PIC micros and C - source and sample code

 

[Nikunj Tanna]

The issue is solved. I tried three different PIC 16f876a after that, the fourth one did work for me.. It works.. Thanks

NIKS