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Program internal EEPROm

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edi

Joined: 22 Dec 2003
Posts: 82

Program internal EEPROm
Posted: Mon May 17, 2004 1:39 pm

Hi, I have parameters file of 256 Bytes, that I want to program to the 16F877. What is the recommended way to program the internal EEPROM from the C code. (I can't use RS232 to transfer the file). Edi

PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Mon May 17, 2004 6:01 pm

Quote:

I have parameters file of 256 Bytes, that I want to program to the
16F877. What is the recommended way to program the internal
EEPROM from the C code.

Use a #rom statement, with the starting address at 0x2100.
This address is the start address of the on-chip EEPROM for the 16F877.
Example of how to put a string in EEPROM:

#rom 0x2100 = {"Hello there"}

Example of how to put data bytes in EEPROM:
#rom 0x2100 = {0x01, 0x02, 0x03 }

Put the #rom statement above main(). After you compile the file,
open the EEPROM window in MPLAB. You should see the data there.
---------

Edited on 5-18-04 to put the entire string in quotes, instead of using
single quotes on each character. The newer versions of the CCS
compiler now allow you do this. Also added a separate example
which shows how to put bytes in EEPROM.

Last edited by PCM programmer on Tue May 18, 2004 1:25 am; edited 1 time in total

djpark

Joined: 02 Mar 2004
Posts: 49

Posted: Tue May 18, 2004 1:02 am

PCM programmer wrote:

Is the start address of eeprom different from PIC to PIC? If so, what is a general way to find out the address within the program execution?

-- dj

PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Tue May 18, 2004 1:45 am

Quote:

Is the start address of eeprom different from PIC to PIC ?
If so, what is a general way to find out the address within the program
execution?

I haven't checked the data sheet for every PIC, so I don't know
how many different addresses they use. I do know that the 16F877
(etc.) and the 16F628 use 0x2100. The 18F452 and 18F458 use
0xF00000.

To find the address, you can look in the Programming specification
document for each PIC. In the modern documents, they have a
section in the back, titled "Embedding Data EEPROM Information in
the HEX File", or something similar. That section has the address.
In earlier Programming Specification documents, the address may
be in the section on "Data EEPROM Memory", or it might be somewhere
else in the document.

The Microchip website appears to be down at the moment I'm writing
this, so I can't give you a link to the page that has the programming
specifications.

Neutone

Joined: 08 Sep 2003
Posts: 839
Location: Houston

Posted: Tue May 18, 2004 7:52 am

djpark wrote:

PCM programmer wrote:

Is the start address of eeprom different from PIC to PIC? If so, what is a general way to find out the address within the program execution?

-- dj

From program execution the address of the first byte is 0. The 0x2100 address only applies to compile time for the purpose of preloading the EEPROM during programming.

rnielsen

Joined: 23 Sep 2003
Posts: 852
Location: Utah


Posted: Tue May 18, 2004 10:19 am

Thanks PCM programmer. I've always wondered how to do this.

edi

Joined: 22 Dec 2003
Posts: 82


Posted: Wed May 19, 2004 12:54 pm

Thanks you all. Edi

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