Wrong Bootloader Start Address

[JDBC]

I created a custom bootloader based on the SDK 15.3.0 secure bootloader.  At location 0xFF8 I defined the uicr bootloader start address as 0xE4000 but my bootloader actually starts at 0xE8000.  0xE4000-0xE7FFF are all 0xFF.  Will my application still start the bootloader correctly by seeing all the FFs and skipping them until it gets to 0xE8000?

[JDBC]

I'm using the nRF52840.

[Simonr]

Hi

In SDK v15.3.0 the memory layout says Bootloader should be stored between 0xF8000 and 0xFE000, so why have you set the start address to 0xE4000 in your project? 0xFF means the address space is empty I believe, so it will likely not run a bootloader if the startup goes there.

Best regards,

Simon

[JDBC]

0xF8000-0xFE000 was not enough memory space for my custom bootloader.  I'm testing to verify the bootloader will not run.

[Simonr]

Hi

Okay, can you show me where/how exactly you changed the bootloader start address in your application, where it didn't work as intended? You will for example need to do a chip erase if you're changing the start address of the bootloader, you can use either an nrfjprog --eraseall command with the nRF command line tools, or you can use the nRF Connect for Desktop Programmer app to do this.

Best regards,

Simon

[JDBC]

Yes, I use nrfjprog -e and nrfjprog --qspieraseall before programming my custom combined SD/BL/Application file.  Testing showed that you were correct - the bootloader would not run if the bootloader start address was an address starting with 0xFF. Thank you.