Program code now and eeprom later

[MarcosAmbrose]

Hi All,
CCS has a #rom directive that allows bytes of data to be embedded in the final .Hex file and burnt to the eeprom at program time. However I would like to be able to program the eeprom at a later stage and from a seperate file. I'm using both IC-Prog and WinPic800 with a JDM programmer, but I can't see anywhere in either of these applications where I can program just the eeprom without erasing the code first.

Could someone kindly set me in the right direction. -Cheers

[treitmey]

I'm sorry I don't know how to do what your asking.

BUT, could you tell us why you want to do this?

Perhaps there is another way around your problem.

[Fro_Guy]

Hi

I dont know if this is what you are asking but i had a problem where i had to change the eeprom whenever i have had to write a new PIC. What i did was write a program to change the eeprom to the orginal hex file, and then called a .bat file with the program to invoke the compiler and write that version to the PIC.

[MarcosAmbrose]

OK, Im developing an application that uses parameters stored in the eeprom and these parameters act as security keys. Due to the security implications, I didn't want to write the parameters into the source code where they'd be visibly open. Furthermore, these parameters would change from time to time.

I was initially thinking that I'd program the pic code first and then the eeprom with the parameters at a later date from a seperate file. However I'm now thinking it would be better to transfer the security parameter to the eeprom via the serial uart and write a little app that runs on a pc to handle the transfer. -Any thoughts or ideas?

[bsodmike]

Marcos,

What you've suggested would work, but you'd want to impliment some sort of security over the RS232 link, so you would in essence transmit encrypted data to the PIC and it'll perform the decryption on board.

I've not looked in to algorythms suchs as say AES-128, etc but if you google around you might find something that you can implement quite effectively.

[asmallri]