Eeprom accesses

[BradenBurton]

Greetings all,

Ok - I should already know this one (being a programmer), but I just want to double check.

When using READ with the eeprom (within the picaxe), the number of accesses/reads can be unlimited, with no side affects, right ?
When using WRITE with the eeprom (within the picaxe), the eeprom can only take so much (100,000 from memory) - so use only as part of a setup and NOT in any loops if it can be helped, right ?

Thanks all
Braden

 

[BCJKiwi]

Correct.
However the the write life is 1,000,000.

The reason is pretty simple;
Writes require elevated voltages internally within the Flash Ram in the chip to 'burn' the memory locations to make them (semi) permanent so this can only be done a limited number of times.

Reading does not have any effect on the memory location.

A parallel might be a notebook in which you write with a pencil;
The page can be written multiple times but the act(s) of writing and rubbing out and writing again in the same place cannot be done an infinite number of times without permanent damage.
However reading causes no damage (to the page!).

 

[demonicpicaxeguy]

acording to the microchip application notes on the eeprom memory in the pics
you can get 2 million even up to 3 million write cycles out of the memory if you run it at lower voltage, basically the lower the voltage the high number of write cycles it will take,

do a search for "eeprom endurance testing" you should find my thread i started a while ago where i did an endurance test on a pic running at 5v i got a few more than a 1 millions out of it then

 

[BradenBurton]

Thanks

Thanks guys,
just thought I would check. Interesting thread demonicpicaxeguy