Memory Layout nRF52840 without SoftDevice

[Pietro Beraldini]

Hi, I'm not able to find the memory layout of the nRF52840 without the SoftDevice. I'm working with the nRF52840-Preview-DK and the SDK v15.0.0. I don't need the SoftDevice and I would like to better understand how the bootloader and the MBR work and where they are located. Can someone help me? I found the documentations about MBR and bootloader with regard to SoftDevice, but I didn't find nothing about MBR and bootloader without SoftDevice.

[Andre]

The bootloader can technically be located in any unoccupied place in the flash. You set the address of the bootloader in the UICR.NRFFW[0]  register and the MBR will start the bootloader on boot.

[Pietro Beraldini]

Thanks for the answer. Do you know an example provided by Nordic in which can I test it?

[bjorn-spockeli]

Hi Pietro, 

you can simply use the bootloader example from the SDK and modify the start address, this start address will be written to the UICR.NRFFW[0]  register when you flash the bootloader to the nRF52840.

Best regards

Bjørn 

[Pietro Beraldini]

Which example do you mean? Every example of bootloader is related to DFU or SoftDevice, I didn't find an example regarding only the bootloader

[bjorn-spockeli]

The MBR is included in the SoftDevice binary, so if you want only the MBR you will need to flash only parts of the SoftDevice binary. 

I am referring to the projects found in <SDK-folder>\examples\dfu. My understanding was that you simply wanted to verify that the bootloader could be placed in any unoccupied flash region. 

The nRF5 SDK bootloaders perform application validation by comparing a stored CRC against the one computed from the actual application code in flash. IN addition the bootloader is responsible for receiving a new firmware image over a transport layer( UART, USB or OTA with BLE), we do not have any example that only performs the validation part.  It is only our serial  Bootloader that is SoftDevice independent, i.e. it does not use the SoftDevice flash API to write/erase flash during the DFU.