Help understanding Marlin Flash vs Eeprom
October 06, 2012 02:01PM
When I make a change to my Marlin firmware and upload it to my Ramps 1.4/Arduino Mega 2560 board, where exactly is the firmware being stored? In flash memory or eeprom? I ask because it seems that whenever I make a change to the files and upload them with the Arduino IDE, the changes don't seem to be in effect. Do I have to turn off then on the machine? Or is it being loaded to eeprom and I have to 'restore' them with M502. Are they automatically used when the board is reset by Arduino IDE after the upload?

Any info is appreciated.
Re: Help understanding Marlin Flash vs Eeprom
October 06, 2012 09:02PM
You'll have to restore the defaults (M502?) then store those in the EEPROM (M500 or M501 I can't remember which it is), if EEPROM is enabled, then you'll get whatever you last stored there.

Edited 2 time(s). Last edit at 10/06/2012 09:07PM by Polygonhell.
Re: Help understanding Marlin Flash vs Eeprom
October 07, 2012 12:59PM
By this:
if EEPROM is enabled

do you mean:

//define this to enable eeprom support
//to disable EEPROM Serial responses and decrease program space by ~1700 byte: comment this out:
// please keep turned on if you can.
from Marlin?

If that is what you mean, and I leave eeprom turn off, then any changes made are only stored in Flash ?
Re: Help understanding Marlin Flash vs Eeprom
October 18, 2012 12:52AM
Yes - my understanding is that if you do not enable eeprom, your data is only stored in flash and will be overwritten each time you re-upload the firmware.

If you enable eeprom, then after each reset - or when you enter m501 - the eeprom values are copied into flash. So you cannot change settings by modifying source code and ten uploading ( actually I think there is a way by playing around with the version number).

The advantage to eeprom is tat you can tinker with your settings easily - every eeprom parameter is settable with an m command - and easily revert back to your standard settings if things don't work out. If you like your new settings, there is another m50x command to commit everything to eeprom.
Re: Help understanding Marlin Flash vs Eeprom
October 20, 2012 07:11AM
Through trial and error, I can confirm what jbernardis is saying. Personally, I prefer to write all my changes into firmware on PC, flash to arduino and then forget about the rest. Especially during testing.
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