View Full Version : Teensy 3.0 - EEPROM writes not persisting through reboot - wierd

12-14-2012, 12:22 AM

I have not had time to investigate this properly yet but the code I was using with Teensy 2.0 and Teensy 2.0++ for writing to the EEPROM reports to work fine with the Teensy 3.0.

However, when I power cycle the Teensy 3.0 it appears the EEPROM has never been written to and every byte returns 0xFF.

Anyone else had similar or offer an explanation. May weel just be me and I will investigate further and peform more tests as soon as possible to understand it.

Thanks for looking :)

12-14-2012, 12:34 AM
Are you reflashing instead of just rebooting (ie are you pushing the button on the board or just plugging and unplugging)? If yes this is a known issue (http://forum.pjrc.com/threads/4-Teensy-3-0-and-EEPROM-usage?p=9&viewfull=1#post9): the eeprom is actually stored in flash and is wiped by the bootloader. Paul has discussed wanting to change this in the future.

If you are just plugging and replugging, I'd guess something else is going on.


12-14-2012, 05:24 AM

You got it in one. Since I am deep in development I am continually reflashing, I had noticed the odd time it worked and I guessed some capacitance was maintaining the RAM for a few seconds. I now know it was the odd time that I had not reflashed !

Thanks for the help, it was a little confusing to find my non volatile data becoming volatile