5 years, 6 months ago.

Bootloader with header file does not boot

I'm trying to get a super simple bootloader up and running but I'm having issues when I introduce the application bootloader header. I'm running on an LPC1768.

Basically, I'm following the steps laid out here: https://os.mbed.com/docs/v5.10/tutorials/bootloader.html

I've got my example blinky project as my main application and create a new project from scratch for the bootloader. For the bootloader, here is my main for the bootloader:

#include "mbed.h"
#include <stdio.h>

int main()
{
    printf("Starting application...");
    mbed_start_application(POST_APPLICATION_ADDR);
}

Here's the bootloader's mbed_app.json:

{
    "target_overrides": {
        "LPC1768": {
            "target.restrict_size" : "0x20000"
        }
    }
}

and here's the bootloader's AND application's mbed_lib.json - two different files but share the exact same data, as specified is required in the link above:

{
    "name": "application_header",
    "target_overrides": {
        "*": {
            "target.header_format": [
                ["magic", "const", "32be", "0x5a51b3d4"],
                ["headerVersion", "const", "32be", "2"],
                ["firmwareVersion", "timestamp", "64be", null],
                ["firmwareSize", "size", "64be", ["application"]],
                ["firmwareHash", "digest", "SHA256", "application"],
                ["headerCRC", "digest", "CRCITT32be", "header"]
            ]
        }
    }
}

And finally, here is the required line in my main application's mbed_app.json:

"LPC1768": {
            "target.bootloader_img": "../mbed_bootloader/BUILD/LPC1768/GCC_ARM/mbed_bootloader.bin"
        }

When I compile and flash the main application (which bundles in the bootloader) I don't see the printf in the bootloader application at all. It's as if its not run at all for some reason. Yet, it's worth noting that when I remove the header mbed_lib.json from both projects, the bootloader kicks in just fine and I not only see the printf but it then successfully loads in the blinky application.

Can anyone help me? Even any general insight on how and where the bootloader header is used would also probably be useful.