about programming Atmel 89c51

[neera]

hi everyone !!!!!!!!!!!!!!
I am making a project using Atmel 89c52 and i am stuck up at a point...
well i need to save a value permanently in its memory (so obviously i
cant utilize the RAM for the purpose). So i need to punch in the value
in ROM. Well is it possible that using any compiler statements of KEIL
the value is placed in the ROM and later on read from there????
please tell me a way to permanently store a value in this
microcontroller.

thanks

 

[Rich Grise]

hi everyone !!!!!!!!!!!!!!
I am making a project using Atmel 89c52 and i am stuck up at a point...
well i need to save a value permanently in its memory (so obviously i
cant utilize the RAM for the purpose). So i need to punch in the value
in ROM. Well is it possible that using any compiler statements of KEIL
the value is placed in the ROM and later on read from there???? please
tell me a way to permanently store a value in this microcontroller.

According to the data sheet I'm looking at
http://www.atmel.com/dyn/resources/prod_documents/doc0313.pdf
(BTW, is that 89C51 or 89C52?), it's doable, but a real pain in
the ass.

Why not google "serial eeprom"?

Good Luck!
Rich

 

[Rich Webb]

hi everyone !!!!!!!!!!!!!!
I am making a project using Atmel 89c52 and i am stuck up at a point...
well i need to save a value permanently in its memory (so obviously i
cant utilize the RAM for the purpose). So i need to punch in the value
in ROM. Well is it possible that using any compiler statements of KEIL
the value is placed in the ROM and later on read from there????
please tell me a way to permanently store a value in this
microcontroller.

Presumably something on the order of

#include <stuff>

#define THINGS

int ValueInROM = 0x1234;

main()
{
int Local;

Local = ValueInROM;
}

should work, if I correctly interpret "compiler" and "KEIL" to imply
that you're working in C. Otherwise, look for the MOVC instruction.

 

[Peter Bennett]

hi everyone !!!!!!!!!!!!!!
I am making a project using Atmel 89c52 and i am stuck up at a point...
well i need to save a value permanently in its memory (so obviously i
cant utilize the RAM for the purpose). So i need to punch in the value
in ROM. Well is it possible that using any compiler statements of KEIL
the value is placed in the ROM and later on read from there????
please tell me a way to permanently store a value in this
microcontroller.

thanks

If you know the value at compile time, just include it as a constant
in your program.

Otherwise, I think you will need to use an external serial EEPROM. I
use a 93C46 (I think - something like that) to store calibration
values on some of my 89C52 projects.

I don't think there is any way for a program to write to the on-chip
program EEPROM on the 89C52. Some other processors do have some
program-accessible EEPROM


--
Peter Bennett, VE7CEI
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[Paul Burke]

Well is it possible that using any compiler statements of KEIL
the value is placed in the ROM and later on read from there????

This is one of my pet peeves, that there isn't a standard way of doing
this. I use Raisonance, not Keil, and not having done anything with 8051
for 6 months I've forgotten whgat they use. So you'll have to read the
manual. It's usually something like

code int xxx = yyy;

or some misuse const:

const int xxx = yyy;

Though I've seen still others where you have to use constructs like
#pragma segment, that force subsequent declarations to the desired area,
then remember to change back again afterwards.

C has only been around since the 70s, so it's a bit hasty to expect them
to have noticed the problem yet.

Paul Burke