i m working on a project with 89c51rd2.
my problem is how to store some datas in memory...
a passwoed for example, i store a defult value for the password when i programming. and i want the user can change the password. but if the user shuts down the device or wants to change batteries then the user works the device again, the password will take the default value again.
how can i solve this? im using C language with keil.
i cant store any values in code memory. can the data memory remember the value?
Where is the 8051's static memory?
i want to select an address an store the password there. and i wont use a default value. But the problem is which memory of 8051 should i use, and how can i use it.
i wanna select an address and when program starting up i will check that address, if there is no value, i will store 1234 value into there as password. when user wants to change the password i will change the value of that address.
well can i select an address in code segment(or any memory space which dont forget the value) and how can i store a value into there? eg. i wanna store a byte to FFF0 address in code segment. is it possible?
Keil clears all memory spaces with the file "STARTUP.A51" while starting up the device. Somebodies told that if i modify this file as i want, keil will not clear the memory while starting up.
But nobody told how to do it. if you can not figure that out, go back to basics
anyhow, what does that have to do with your problem, RAM is lost during battery change
do not try to run before you have even learned how to crawl
Erik