Low Power Mode (BSR) (backup-self-refresh)

Hi all,
I was able to run the GiantBoard and put it into the Ultra Low Power Mode 1 (ulp1) as it is pre-configured in the uEnv.txt file.
I was also able to wakeUp the device by pressing the button.

Now I would like to try the BSR (backup-self-refresh) mode.
I exchanged the line in uEnv.txt
optargs=atmel.pm_modes=standby,ulp1 giantboard.disable_charging=1
optargs=atmel.pm_modes=standby,backup giantboard.disable_charging=1
Afterwards I rebooted the device and checks by reading the file /proc/cmdline, if the change was applied.

Then I wrote “mem” to /sys/power/state

The problem appeared after pressing the button, to wakeUp the device.
The UART-TX-PIN shows:
BKP: Failed to find the canary! Rebooting
BKP: @0xf8044000: 0x1 @0x20b0b538:0x9505f6cd -> resume @0x2010cb4cÿRomBOOT
in a endless loop.

Do I forgot anything ?

Thanks for your help.

Best regards

There is a problem with mem refresh that I hadn’t been able to track down. Partly why I never mentioned this mode in my power management write up. I did some research a little while ago and found others with a similar issue but no solution.