Writing to eeprom memory inside a picaxe

[@lowa]

Hi everybody
Is it possible to write to the non volatile memory from inside a program on a 18x so the written value(s) will still be there after the power is tunned off and on again

Thanks

@lowa

 

[testerrrs]

Yes. Have a look at the 'read' and 'write' commands in the BASIC manual. How much available memory you have will depend on program size and/or variety of PICAXE.

*j

 

[crossthreaded]

Yes the 18x eeprom can be accessed using read and write commands and, yes, it will retain the data during a power cycle. However, when you download software to the picaxe, it clears the eeprom.

If you want to maintain the eeprom values during a software update I think you have to have a routine to upload the eeprom values so that you can restore them after (or during) the next software download.

 

[@lowa]

Yes the 18x eeprom can be accessed using read and write commands and, yes, it will retain the data during a power cycle. However, when you download software to the picaxe, it clears the eeprom.

If you want to maintain the eeprom values during a software update I think you have to have a routine to upload the eeprom values so that you can restore them after (or during) the next software download.

Thank you for your reply.
What is the instruction name to put data in the eeprom during a software download

@lowa

 

[BCJKiwi]

Check out "eeprom" in manual2

 

[@lowa]

Is the eeprom instruction only executed on software download or will it been executed every time I power the chip aferward?

@lowa

 

[BCJKiwi]

It's in the program on the chip so will execute every time the program passes the line.

So if it's at the top BEFORE your Main: loop, then it will only execute once at power up.

If it is in the body of the program somewhere then it will re-write to the eeprom every time the program hits the line.

Remember eeprom has a finite number of writes so it is recommended to use it in the once per power up mode.
For RAM type storage on 18X (no write limits), see Manual2 page12

 

[westaust55]

The EEPROM command is a Programming Editor control not a BASIC instruction that is not run by the program within the PICAXE.

It is used to a method of pre-loading the microcontrollers data memory only at the time a program is downloaded. If no EEPROM command is used the values are automatically cleared to the value 0.

 

[westaust55]

as geforce has stated, you must use the READ and WRITE commands to read data from EEPROM or write data to EEPROM within a running program.

 

[BrendanP]

Another option is to use external eeprom, that will give you plenty of storage room and it wont be affected by program downloads into the picaxe.

 

[@lowa]

Thanks Westaust55
This is exactly want i want to do.
This is very clear in the description of the eeprom instruction.
i can go back to programmation

@lowa