16F877 internal EEPROM still can't write / read

[David Lu]

Hi,All:
I am posting my roblem on Feb. 26,(I trying to use C language to write and read internal EEPROM on my 16f877, but it can not working) . I am very thanks about some friends give me good idea. But both read and write is not working, I open EEPROM Windows , each bute is 0xff, so I am still need some help.
I use C2C-plus IDE, MPASM and MPLAB IDE. I think program maybe no problem, is it necessary to set CONFIG register ( address: 0x2007) CPD ( Data EE memory code protection bit), and I don't know how to set it as 1.
Thanks.

David

my program is:
void write_eeprom ( char addr, char data ) // Write eeprom
{
while ( EECON1 & WR); // check completion of last write
EEADR = addr; // set address register
EEDATA = data; // set data register
disable_interrupt( GIE ); // Enable Global Interrupts
clear_bit ( EECON1, EEPGD );
set_bit( EECON1, WREN );
EECON2 = 0x55;
EECON2 = 0xAA;
set_bit( EECON1, WR ); // write command
clear_bit( EECON1, WREN ); // inhibit further writing
}


char read_eeprom ( char addr ) // Read eeprom
{
EEADR = addr; // set address register
clear_bit (EECON1, EEPGD );
set_bit(EECON1, RD ); // read command
return (EEDATA);
}
___________________________
This message was ported from CCS's old forum
Original Post ID: 12267

[PCM programmer]

:=Hi,All:
:=I am posting my roblem on Feb. 26,(I trying to use C language to write and read internal EEPROM on my 16f877, but it can not working) . I am very thanks about some friends give me good idea. But both read and write is not working, I open EEPROM Windows , each bute is 0xff, so I am still need some help.
:=I use C2C-plus IDE, MPASM and MPLAB IDE. I think program maybe no problem, is it necessary to set CONFIG register ( address: 0x2007) CPD ( Data EE memory code protection bit), and I don't know how to set it as 1.
----------------------------------------------------------

You're using the C2C compiler. Did you know that this forum
is for a different compiler (CCS) ?

I'm not trying to kick you off this forum
but C2C has its own forum. Go here, and
click on the link for "C Programming with C2C-plus compiler".
<a href="http://www.picant.com/boards/ikonboard.cgi" TARGET="_blank">http://www.picant.com/boards/ikonboard.cgi</a>

I read that forum a little bit, and I think they're
discussing your problem on Page 5 of the forum.
Click on the "5" down at the bottom of that page.
Then read the article called:
"eecon1...not working on pic16f876a"

Basically, the Admin recommends that the person
use the proper header file, which is supplied with C2C.
For example, you have obviously got your code from here:
<a href="http://www.picant.com/c2c/examples/eeprom.html" TARGET="_blank">http://www.picant.com/c2c/examples/eeprom.html</a>
But, you have changed all the register names by removing
the underscore "_" symbol in front of them. The Admin
on that forum says that is the problem !
You are supposed to use the symbol names that come
in their header file, which they have here:
<a href="http://www.picant.com/c2c/examples/p16f877x.html" TARGET="_blank">http://www.picant.com/c2c/examples/p16f877x.html</a>
(Also, include that header file in your program).

You should read the C2C forum, if you are using that compiler.
___________________________
This message was ported from CCS's old forum
Original Post ID: 12269

[David Lu]

Hi, PCM Programmer:

Thank you give me much advice.
Now the problem is in MPLAB I check the EEPROM WINDOW,all unit is 0xff, and running in STEP by step, but can't change WR (Bit 1 in EECON1), when do " bsf EECON1,D'2'; set_bit_EECON1,WREN))", the EECON1 (address 0x018c) can change the value, but do "bsf EECON1,D'1';(set_bit(_EECON1,WR))" can't change regiser EECON1's value. I try to change bit 1 in EECON1 to "1" manually, but after the next command running, the bit will change to "0" automatically.
I think that is why I can't read and write EEPROM. But I don't
know how can I do now. I try to change different bit of MPLAB, but still no way.

David
___________________________
This message was ported from CCS's old forum
Original Post ID: 12288

[David Lu]

Hi,

I check it again, EECON1.WR will be clear by hardware, when write cycle to the EEPROM is complete, it will be '0'.
so, I also don't know how to solve my problem.

David
___________________________
This message was ported from CCS's old forum
Original Post ID: 12296

[chris_1982]

:=Hi,All:
:=I am posting my roblem on Feb. 26,(I trying to use C language to write and read internal EEPROM on my 16f877, but it can not working) . I am very thanks about some friends give me good idea. But both read and write is not working, I open EEPROM Windows , each bute is 0xff, so I am still need some help.
:=I use C2C-plus IDE, MPASM and MPLAB IDE. I think program maybe no problem, is it necessary to set CONFIG register ( address: 0x2007) CPD ( Data EE memory code protection bit), and I don't know how to set it as 1.
:=Thanks.
:=
:=David
:=
:=my program is:
:=void write_eeprom ( char addr, char data ) // Write eeprom
:={
:=while ( EECON1 & WR); // check completion of last write
:=EEADR = addr; // set address register
:=EEDATA = data; // set data register
:=disable_interrupt( GIE ); // Enable Global Interrupts
:=clear_bit ( EECON1, EEPGD );
:=set_bit( EECON1, WREN );
:=EECON2 = 0x55;
:=EECON2 = 0xAA;
:=set_bit( EECON1, WR ); // write command
:=clear_bit( EECON1, WREN ); // inhibit further writing
:=}
:=
:=
:=char read_eeprom ( char addr ) // Read eeprom
:={
:=EEADR = addr; // set address register
:=clear_bit (EECON1, EEPGD );
:=set_bit(EECON1, RD ); // read command
:=return (EEDATA);
:=}
:=


Im not sure if this will help you but i also have a PIC16F877 and could not get the internal eeprom write to work in the MPLAB simulator BUT it DOES work when run on the PIC.
___________________________
This message was ported from CCS's old forum
Original Post ID: 12300

[chas]

:=Hi,All:
:=I am posting my roblem on Feb. 26,(I trying to use C language to write and read internal EEPROM on my 16f877, but it can not working) . I am very thanks about some friends give me good idea. But both read and write is not working, I open EEPROM Windows , each bute is 0xff, so I am still need some help.
:=I use C2C-plus IDE, MPASM and MPLAB IDE. I think program maybe no problem, is it necessary to set CONFIG register ( address: 0x2007) CPD ( Data EE memory code protection bit), and I don't know how to set it as 1.
:=Thanks.
:=
:=David
:=
:=my program is:
:=void write_eeprom ( char addr, char data ) // Write eeprom
:={
:=while ( EECON1 & WR); // check completion of last write
:=EEADR = addr; // set address register
:=EEDATA = data; // set data register
:=disable_interrupt( GIE ); // Enable Global Interrupts
:=clear_bit ( EECON1, EEPGD );
:=set_bit( EECON1, WREN );
:=EECON2 = 0x55;
:=EECON2 = 0xAA;
:=set_bit( EECON1, WR ); // write command
:=clear_bit( EECON1, WREN ); // inhibit further writing
:=}
:=
:=
:=char read_eeprom ( char addr ) // Read eeprom
:={
:=EEADR = addr; // set address register
:=clear_bit (EECON1, EEPGD );
:=set_bit(EECON1, RD ); // read command
:=return (EEDATA);
:=}
:=

There is a note in the MPLAB development mode set up window (see details) that indicates that single stepping does not work for program memory and data (EEPROM) reads and writes.
___________________________
This message was ported from CCS's old forum
Original Post ID: 12305