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Spark STM32 Bootloader

Careful! Low level dragons here!

  • Really make sure you have a working programmer shield and an ST-link programmer.
  • Is this a brand new core from scratch (that you made? nice!) goto 1, or is it this a core that came from Spark - goto "unlocking your bootloader"

Please note this documentation is for the Core only. The photon automaatically updates the bootloader as needed.

Unlocking your bootloader

Welcome! The bootloader on the stm32 is protected by a "write protect" flag that helps prevent accidental "bricking" of a core for those without a programmer shield / st-link programmer. But that's not you, you want to fully erase your core, or re-write your bootloader, and you're not scared of "bricking" anything.

  • Grab the "unlocker" from here: (https://github.com/spark/firmware/tree/master/bootloader/tools (use "raw")
  • dfu that with a: dfu-util -d 1d50:607f -a 0 -s 0x08005000:leave -D unlocker-firmware.bin
  • Your core should restart, flash some lights, and end with a 'green' flash before wiping saved wifi profiles and resetting
  • Your bootloader is unlocked!

1. Make sure you have st-flash installed, or have a copy of the ST-Link Utility software.

2. Grab a copy of the latest bootloader from here:

https://github.com/spark/firmware/blob/master/bootloader/build/bootloader.bin?raw=true5.) With your core in your programmer shield / st-link connected, lets re-flash some stuff!

  • In the windows utility set device -> settings to "connect under reset" true! (if you can't find this that's okay)
  • Do a full erase of your core, do this a few times, if you're in the windows utility, view the memory and make sure it's zero-ed out.
  • Write your bootloader.bin back to 0x08000000
  • Congrats, you re-wrote your bootloader!

3. Lock your bootloader back up! (Optional, but recommended)

4. Okay, lets keep going and update the radio driver on the CC3000

It's time to write some stuff to external flash!

1. Lets make some keys (optional step if your keys have been fine):

    openssl genrsa -out core.pem 1024
    openssl rsa -in core.pem -pubout -out core_public.pem
    openssl rsa -in core.pem -outform DER -out core_private.der

2. Flash your new private key:

`dfu-util -d 1d50:607f -a 1 -s 0x00002000 -v -D core_private.der`

3. Grab the server public key, and flash it: https://s3.amazonaws.com/spark-website/cloud_public.der

`dfu-util -d 1d50:607f -a 1 -s 0x00001000 -v -D cloud_public.der`

4. Grab the latest firmware and flash it

https://github.com/spark/firmware/blob/master/main/build/core-firmware.bin?raw=true
    # to the factory reset spot
    dfu-util -a 1 -s 0x00020000 -v -D core-firmware.bin

    ## to the main firmware spot
    dfu-util -a 0 -s 0x08005000:leave -D core-firmware.bin

5. If you made new keys, be sure to send someone at Spark your new public key, along with your core id, otherwise your core won't connect to the cloud again!

(Thanks to David for putting this together) Ref: https://community.spark.io/t/st-link-programmer-shield-only-so-youve-decided-you-want-to-update-your-bootloader-and-everything/2355