How to know which bank got booted when working with BFB2 bit in STM32L4 MCU's

[MDinn]

Hi,

I'm implementing an OTA system using the L486VG MCU.

This one has the dual bank option and the BFB2 option bit to enable to boot in Bank2.

It works and I can constantly swap the banks and erase and read them.

Only when the BFB2 bit is set and there is no valid firmware in Bank 2 it boots from Bank 1.

The problem is that I need logic in my firmware to know what bank got booted so I can erase the correct bank before writing my new firmware. How could I do this? At the moment I just check the BFB2 bit, but that is no assurance that it's in Bank 2.

Thanks,

Marvin

[Tesla DeLorean]

Pretty sure you can read the mapping register. Failing that you can put a unique identifier in each, and perhaps a common boot loader at the front of each bank that forks.​

[TDK · Accepted solution]

Check the SYSCFG_FB_MODE bit to see if it accurately reflects what is mapped.

[MDinn]

Thanks for the info!

For others searching for more info on this you can read the FB_MODE bit like this:

if(SYSCFG->MEMRMP & 0x00000100)
{
	//bank2 is mapped
}
else
{
	//bank1 is mapped
}