Using BLE OTA DFU to update the Bootloader itself

RE: Using BLE OTA DFU to update the Bootloader itself

user46136 — Wed, 15 Jun 2022 04:35:57 GMT

We also have the same version for our custom bootloader. Do I need to roll the version number somewhere to get past a no-downgrade test? I don't think we have downgrade prevention turned on, but I don't know where to look to find out.

RE: Using BLE OTA DFU to update the Bootloader itself

user46136 — Wed, 15 Jun 2022 04:33:17 GMT

I don't think we can use buttonless Secure DFU without updating the bootloader. I assume that if we just detect the button is down as we boot into our HDT app and jump to the bootloader on that condition, the bootloader will just jump right back into our HDT app because it knows there is a valid app at the prescribed address.

RE: Using BLE OTA DFU to update the Bootloader itself

user46136 — Wed, 15 Jun 2022 04:29:55 GMT

The app works as expected when the bootloader is present and when the bootloader is not present. Our issues are just with getting the bootloader to update the bootloader itself.

RE: Using BLE OTA DFU to update the Bootloader itself

user46136 — Wed, 15 Jun 2022 04:23:46 GMT

We actually have the larger bootloader expanded and using uECC in the units in the field. That bootloader works. Well it will work once and then forever jump to the installed app. So we are not trying to change the size of the bootloader from what is already in the target hardware. I would assume we could leave the MBR and Softdevice in there, and just update the bootloader itself. Is that not possible?

RE: Using BLE OTA DFU to update the Bootloader itself

user15146 — Tue, 14 Jun 2022 09:07:39 GMT

Hi,

[quote user=""]the update appears to work, but the new advertising name does not show up,[/quote]

Does the app work as expected when the bootloader is not present?

[quote user=""]Our issue is that we have a thousand units in the field with just the bootloader and no app in them. We can add the app once, but then we can never update it again because the DFU will always jump to the app after that. So we want to update the custom bootloader we put in there to our new custom bootloader that will jump to DFU if a button is held down at boot. We can make this work when programmed with a J-link, but we can't do it over the air which means we would need to open the cases of the 1000 units in the field that contain just the bootloader and use a Jlink and a cable to update the bootloader.
[/quote]

We have support for buttonless DFU as well. You can use the Buttonless Secure DFU Service to jump from the app to the bootloader. See this example: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/ble_sdk_app_buttonless_dfu.html

RE: Using BLE OTA DFU to update the Bootloader itself

user14028 — Tue, 14 Jun 2022 07:53:13 GMT

You don't need to include the bootloader settings page to the DFU package. The settings page is only needed if you flash the binary to the target with a programmer.

The other issue is the bootloader start address. The one thing you can't do using DFU is to change the size of the bootloader. I'm not sure if there are workarounds to this, but I believe it is not supported.