Combining DFU bootloader with application that doesn't use softdevice.

[JenR]

I am using SDK15.3.0 and softdevice 6.1.1 on a nrf52DK.

I have a binary (compiled contiki application) that works when I flash it using nRF Connect. It is flashed from address 0x0000000 to 0x00008318. 

Now I want to be able to update this binary using DFU, so i need a bootloader with DFU. My plan is to reboot from my application into DFU mode when necessary using the GPREGRET register.

I am using the secure_bootloader_ble_s132_pca10040_debug bootloader. When I flash this bootloader and then do a DFU with the example ble_app_buttonless, I see the buttonless example is flashed from address 0x00026000. This is all working.
Now I think I can just replace the buttonless example with my application, so my binary should be flashed from address 0x00026000 (just like the buttonless example) I guess. I used the srec_cat tool to offset my binary from 0x0000000 to ox00026000. 

After doing this, I do a DFU update with my binary. I see it is flashed on the correct location. The problem is that my application does not start. Any idea what could be the issue?

[JenR]

Just to clarify, below you can see the memory usage of the working ble_app_buttonless example. The buttonless example is written from 0x00026000 to 0x000329E8. The other occupied space is the bootloader and the softdevice I guess.

Below is my application, it also starts at 0x00026000, the bootloader and softdevice (which is not used by my application) are also present. I would assume the bootloader gives control to the softdevice and the softdevice will give control to the application at address 0x00026000, which is where my application is.

[Amanda Hsieh]

Hi, 

You cannot use the secure_bootloader_ble to update with the application that doesn't use the SoftDevice.

You should use Secure DFU Bootloader over Serial Link (UART/USB) e.g. pca10040_uart instead if you don't use BLE.

-Amanda H.

[Turbo J]

JenR said:

I used the srec_cat tool to offset my binary from 0x0000000 to ox00026000. 

VERY bad idea. Cortex-M binaries are linked on a specific address and will not work anywhere else in flash. You need to re-compile (or at least re-link) your application for the new 0x260000 start address.

[JenR]

Hmm I was afraid this would not be that simple. Any idea on how to link the binary to a specific address? I am using the arm-none-eabi-gcc compiler.

[JenR]

I do want to use BLE to do the DFU. My application does not use BLE. The idea is that my application decides when to enable the bootloader DFU with a softreboot (and setting the GPREGRET register). When the DFU is activated I can use BLE to connect to the DfuTarg and do the update.