DFU without rebooting nRF

[honsch]

Is there a supported way of doing an unsecure flash (the nRF is hardwired via UART to a secure processor) without rebooting? 

The HW design the nRF is integrated with uses the nRF as as the main CPU power sequencer and thus cannot be rebooted to allow DFU update from that CPU.

[honsch]

Hug,

We're not using a bootloader, our app was originally based on the ble peripheral uart example. 

The SDK is 15.0.0 a53641a with softdevice 132 v6.0.0.

The DFU  happens after the softdevice is enabled via a command over a hardwired serial connection.  The nRF's main job is reading a bunch of sensors and acting as a BT conduit to the main CPU. 

Thanks,

Eric

[Hung Bui]

Hi Eric,

I understand that you are not using the bootloader.

But as your requirement we need to run your application as a bootloader (so that you can replace the softdevice, change the vectortable location etc). 

To run your application as a bootloader you need to follow what we do in our bootloader and implement that in your application. 

In SDK v15.0 to tell the MBR that you have a bootloader (at address 0x40000 for example) you need to write to UICR 

Please have a look at the attribute commands inside nrf_bootloader_info.c , this is where we write to UICR to tell the MBR where the bootloader (your application ) is. 

[honsch]

I cannot use the Nordic supplied methods for switching which program is running.

Using the Nordic bootloader requires resetting the CPU to switch programs and I cannot do that.  This is a REQUIREMENT of the hardware design.

How do I turn off the memory protection so that I may access all of the CPU registers?  If this is not possible then we cannot have any DFU code. It is that simple.

Thanks,

Eric

[Hung Bui]

You don't need to reset CPU to switch program. Please have look at nrf_bootloader_app_start() function. 

You always have access to all of CPU registers (interrupt) when you are in bootloader mode. 

[honsch]

Looking at the bootloader code filled in the missing gaps.

Thanks for letting me know where the correct process is.