Version Check in dfu_init_prevalidate

[WestCoastDaz]

The comment in dfu_init_prevalidate says the following

  // To support application versioning, this check should be updated.
// This template allows for any application to be installed. However, 
// customers can place a revision number at the bottom of the application 
// to be verified by the bootloader. This can be done at a location 
// relative to the application, for example the application start 
// address + 0x0100.

Is there a recommendation as to what form of structure should be stored at address + 0x0100?

Thanks, Darren

[shibshab]

Which version of the SDK are you using? In the latest versions it is interpreted as a uint32_t, but should be verified by inspecting how the bootloader reads the value stored at the given address.

[Hung Bui]

Hi Darren,

It's up to you to decide where you want to locate the application version and how you should check and compare. It doesn't need to be application address + 0x0100. And it should not be because most likely your application has bigger size than 0x0100. I would suggest to put it at the end of your application image size or any location that you know for sure will not be used by the bootloader as the swapping area.

The structure can be anything, could be simply a 32bit word to tell which application version you currently have. So if the image you are receiving is older than the one the device has then the device can reject this update. But this also mean you can't do downgrading your device. It's all up to you to define this check.

[WestCoastDaz]

Hung,

Thanks for the reply, but I don't really understand your comment "And it should not be because most likely your application has bigger size then 0x100". Isn't it OK to force the linker to place the version structure at this address? Application address + 0x0100 should would be 0x1D00 which isn't near the bootloader or pstroage.

[Hung Bui]

@Darren: You are right, I was thinking of "a revision number at the bottom of the application " then the + 0x100 wouldn't make much sense. Yes, you can tell the linker to force place the version data in a specific place in flash and it could be at application address + 0x100. Sorry about that.

[Arjun]

Hi Hung Bui,

Can you give an example on how to modify linker script to achieve this? I do not have too much experience with linker scripts.

Thanks, Arjun