NRF52810 bootloader size related questions

[haricane]

I'm looking to build a custom bootloader for my NRF52810 device. I'm developing on nrf sdk 17 with SD 112. I will be leveraging the secure bootloader example and re-using code. 

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/lib_bootloader.html?cp=8_5_0_3_5_0_7#lib_bootloader_memory

Can you please clarify what the last line means "The size of the bootloader is fixed for the lifetime of the device. This is because the location (MBR_BOOTLOADER_ADDR) that stores the start address of the bootloader is not (safely) updateable. See the SoftDevice Specification for more information."

Am I not able to build a smaller custom boot loader? And write its start address into the UICR.NRFFW[0]? More importantly, if I write a smaller bootloader, am I not able to use the flash space saved for my application?

Secondly, all the DFU examples in the SDK seem to start at 0x22000 , instead of the memory layout in above link which says Bootloader for nrf52810 starts at 0x28000. Any reason for this? Are the DFU examples larger than the 24k set aside for bootloader in nrf52810?

Regards,

Hari

 

 

[Jørgen Holmefjord]

Hi,

Can you please clarify what the last line means "The size of the bootloader is fixed for the lifetime of the device. This is because the location (MBR_BOOTLOADER_ADDR) that stores the start address of the bootloader is not (safely) updateable. See the SoftDevice Specification for more information."

Am I not able to build a smaller custom boot loader? And write its start address into the UICR.NRFFW[0]?

Yes, you can build a smaller bootloader. The line implies that you can't change the bootloader size for a future bootloader version, and update the bootloader through DFU with the smaller/larger bootloader.

More importantly, if I write a smaller bootloader, am I not able to use the flash space saved for my application?

If you build a smaller bootloader, you can use the saved space for your application. Note that the secure bootloader is already quite optimized from our end, so you may not be able to reduce the size by much.

Secondly, all the DFU examples in the SDK seem to start at 0x22000 , instead of the memory layout in above link which says Bootloader for nrf52810 starts at 0x28000. Any reason for this? Are the DFU examples larger than the 24k set aside for bootloader in nrf52810?

Not sure which examples you looked at, but the secure BLE bootloader in "nRF5_SDK_17.1.0_ddde560\examples\dfu\secure_bootloader\pca10040e_s112_ble" has a start address of 0x28000 and a size of 0x6000. The debug projects may be larger, as they may include additional debugging/logging capabilities, etc.

Best regards,
Jørgen

[Taylor]

Hi, I have the same question with nRF52810.

S112 bootloader's ROM start from 0x28000, so my application start from 0x19000+0xF000. But when my application's bin file over 52k, DFU will show insufficient resources.

[Jørgen Holmefjord]

Have you allocated some pages for application data, through NRF_DFU_APP_DATA_AREA_SIZE? Looks like you are missing 2 pages for the full available application size in the nRF52810 chip with s112.

[Taylor]

YES! Ihave found it!