nRF5340 takes too long from Power ON to start executing the main application

[neo_here]

Hi, we have a custom nRF5340 based device. Has NISB and MCUBoot Enabled. It takes about 2.5 seconds to get into the application and BLE advertisement to start.

Wanted to know how do we go about narrowing down the cause and potential solutions.

We are on nRF Connect SDK 2.6.1

[Elfving]

Have you tried this on more than one board and nRF?

There are things that can make the boot-up take longer, like eg. SD card initialization, or a missing DC/DC Converter. But if what you are running on the custom board is exactly that same as what is running quickly on the DK, and the two are otherwise the same then I guess that's not the problem. 

neo_here said:

seems like it's MCU boot which is taking quite a while to find the image and jump to the image. This is on our board with the production firmware. 

I assume you are not using SD card for MCUBoot? And everything regarding MCUBoot was the same on the DK?

Regards,

Elfving

[neo_here]

No we don't use SD Card. We use QSPI with an encrypted external flash. 

[Elfving]

Could you try disabling the external flash on the board, to see if that makes a difference?

Regards,

Elfving