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
According to the data sheet I'm looking at
Why not google "serial eeprom"?
Good Luck! Rich
Presumably something on the order of
#include
#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.
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
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
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