Dualbank to Singlebank via BLE DFU

[UncleGravity]

I currently have a dualbank bootloader setup and I'm trying to change it to singlebank. If I burn the singlebank bootloader with the jlink it works fine, but if I use the old dualbank bootloader to update itself to the new singlebank hex, then it doesn't boot. It goes both ways, I can't go from singlebank and dfu the old dualbank hex.

On the other hand, If I burn the singelbank hex and try to dfu another modified singlebank hex, then it works perfect.

I'm using SDK 7.1.0 with softdevice 2.0.1 with Keil 5.

All I'm doing to change from between single and dualbank is selecting the correct option form the "dfu_bootloader" dropdown in the "Manage Run-Time Environment" window of Keil.

Is this a known issue?

EDIT:

It works now. I modified dfu_bl_image_validate() in dfu_single_bank.c from this:

uint32_t dfu_bl_image_validate(void) {
    bootloader_settings_t bootloader_settings;
    sd_mbr_command_t      sd_mbr_cmd;

    bootloader_settings_get(&bootloader_settings);

    if (bootloader_settings.bl_image_size != 0)
    {
        uint32_t bl_image_start = (bootloader_settings.sd_image_size == 0) ?
                                  DFU_BANK_0_REGION_START :
                                  bootloader_settings.sd_image_start +
                                  bootloader_settings.sd_image_size;

        sd_mbr_cmd.command             = SD_MBR_COMMAND_COMPARE;
        sd_mbr_cmd.params.compare.ptr1 = (uint32_t *)BOOTLOADER_REGION_START;
        sd_mbr_cmd.params.compare.ptr2 = (uint32_t *)(bl_image_start);
        sd_mbr_cmd.params.compare.len  = bootloader_settings.bl_image_size / sizeof(uint32_t);

        return sd_mbr_command(&sd_mbr_cmd);
    }
    return NRF_SUCCESS;
}

to this:

uint32_t dfu_bl_image_validate(void) {
    bootloader_settings_t bootloader_settings;
    sd_mbr_command_t      sd_mbr_cmd_1;
    sd_mbr_command_t      sd_mbr_cmd_2;

    bootloader_settings_get(&bootloader_settings);

    if (bootloader_settings.bl_image_size != 0)
    {
        uint32_t bl_image_start_1 = (bootloader_settings.sd_image_size == 0) ?
                                  DFU_BANK_0_REGION_START :
                                  bootloader_settings.sd_image_start +
                                  bootloader_settings.sd_image_size;

        sd_mbr_cmd_1.command             = SD_MBR_COMMAND_COMPARE;
        sd_mbr_cmd_1.params.compare.ptr1 = (uint32_t *)BOOTLOADER_REGION_START;
        sd_mbr_cmd_1.params.compare.ptr2 = (uint32_t *)(bl_image_start_1);
        sd_mbr_cmd_1.params.compare.len  = bootloader_settings.bl_image_size / sizeof(uint32_t);

			
		
    uint32_t bl_image_start_2 = (bootloader_settings.sd_image_size == 0) ?
                                  DFU_BANK_1_REGION_START :
                                  bootloader_settings.sd_image_start +
                                  bootloader_settings.sd_image_size;

        sd_mbr_cmd_2.command             = SD_MBR_COMMAND_COMPARE;
        sd_mbr_cmd_2.params.compare.ptr1 = (uint32_t *)BOOTLOADER_REGION_START;
        sd_mbr_cmd_2.params.compare.ptr2 = (uint32_t *)(bl_image_start_2);
        sd_mbr_cmd_2.params.compare.len  = bootloader_settings.bl_image_size / sizeof(uint32_t);

        return sd_mbr_command(&sd_mbr_cmd_1) && sd_mbr_command(&sd_mbr_cmd_2);
    }
    return NRF_SUCCESS;
}

And it works perfectly. I'm sure other people will need this in the future. Particularly if they have a dualbank bootloader (on devices in the field) and they run out of space for runtime code. I hope it helps. Thanks Vidar.

[Vidar Berg]

Hi,

The problem with updating the bootloader from dual- to single bank through bootloader DFU is that the new bootloader expects swap to be at the start of BANK0, while it's actually loaded to BANK1 by the old bootloader. What happens then is that the new bootloader updates itself with whatever data located in BANK0 using the MBR.

The fix is to modify the dfu_bl_image_validate() function in dfu_single_bank.c run verification on both addresses (BANK0 and BANK1). This stops the dfu_bl_image_swap() function from being called twice.

[UncleGravity]

Thanks for the quick reply, Vidar. I edited the original question with my attempt at modifying dfu_bl_image_validate() but it still doesn't work. Perhaps I misunderstood your answer. Am I missing something?

[UncleGravity]

Nevermind, I found the problem. I had not looked into the return values of SD_MBR_COMMAND_COMPARE. It works now! I changed the code in my question to show the working code.