How to restore the information in the external flash?


I have accidentally erased tte Reserved part and the Public Key part in the external flash.

Address Content Size
0x00000 Reserved 4KB
0x01000 Public Key 294 Bytes - 4KB max

How can I restore those two parts and where can I find the information to be restored?


IF you are on Windows,

I have a guide to install the DFU driver:

Once you have DFU driver installed,

  1. download DFU-UTIL ((

  2. download the Public key from

  3. Flash it to the core using: dfu-util -d 1d50:607f -a 1 -s 0x00001000 -v -D cloud_public.der

I have totally no clue what is on 0x00000 but seems like there is something sitting there. @zachary?

be careful when you play with the :dragon_face: in future! But it’s fine. I been through that before and restoring it is fun :wink:

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I think (not 100% sure), that initial reserved block is for system flags and stuff, I think if you do a factory reset it’ll restore itself. (essentially, if firmware is still starting you’re fine, otherwise erasing it works too for the moment, I think!) – I wouldn’t go erasing that sector for fun though. :slight_smile:

We’re not actively using address zero on the external flash chip, but we have it reserved for future use.

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