Bootloader taking higher current consumption upon power on

[Jay_Shah]

Misc info:

1.  SDK Version: v15.3

2.  SD: 6.1.1

3.  Toolchain: IAR v7

I'm trying to use secure_bootloader from the examples but it's taking higher current upon power on. 

Our intention is to integrate the bootloader with the soft device+application but higher current consumption is an issue.

Please check the attached images which we got from PPK.

Can you please help me out on this?

[Kenneth]

The bootloader will do some checksum calculation that take some time during boot,the time will depend on the size of the application, this is a one time operation when chip is powered, and I think it is reasonable to check integrity of the application firmware. You can skip the integrity check for instance when wakeup from system OFF reset:

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsdk_nrf5_v16.0.0%2Flib_bootloader.html&cp=5_1_3_5_0_3&anchor=lib_bootloader_app_start

[asr]

Hi Kenneth,

I did Skip the integrity check ( system OFF reset ) in sdk_config.h file by disabling the below configuration.

// <i> Only CRC checks can be skipped. For other boot validation types, the reset state is ignored.

#ifndef NRF_BL_APP_CRC_CHECK_SKIPPED_ON_SYSTEMOFF_RESET
#define NRF_BL_APP_CRC_CHECK_SKIPPED_ON_SYSTEMOFF_RESET 0
#endif

still I see it drawing higher current.

From the above PPK screenshots, when I do power cycle I noticed that for the duration of around 300ms drawing current about 6-7mA. In the second image about 90ms average current is around 7mA. Can I know what are these bust transactions that we noticed in above PPK screens even after disabling integrity check.

Regards,

asr

[Kenneth]

If you are using an external 32kHz crystal the startup time may for instance be around 300ms, so that may be the first (typical 0.25sec):
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/clock.html?cp=4_2_0_18_3_3#unique_1385509760 

If you erase an flash page, then that can take around 90ms (max 89.7ms):
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/nvmc.html?cp=4_2_0_10_7_0#unique_156661312 

[asr]

We flashed bootloader+softdevice (*.hex) image using the J-link commander. Then we flashed the application (*.zip) image using the "nrf Toolbox" by using the DFU option. I flashed above images on the Nordic nrf52832 DK board and connected the PPK and captured the above screens. I see both the bulk transactions all the time whenever I do powercycle. In the dfu example we just disabled  integrity check ( system OFF reset ) that all. No more changes.

With above reply I can conclude that I can't minimize or avoid both the burst transactions(300ms & 89ms) right?

Regards,

asr.

[Kenneth]

I assume you may reduce the time by using the internal 32kHz RC oscillator instead of the external 32kHz. But do you expect your product to be power cycled frequently?

300ms @ 7mA equal about 200-300 advertising events, unless you power cycle your product many times a day I doubt it will have any impact on the battery life time.