High Current Consumption in Secure DFU Bootloader for SDK 14.2

[SK]

Hi Everyone, 

I am using nRF52832 with SDK v14.2 and SD v5.0.0 on a custom chip. 

Recently i included DFU support to our application. It turns out that secure bootloader is drawing a constant current of >2 mA.

Before integrating secure bootloader support, we managed to bring down application current consumption during system ON (sleep mode) to 30 uA. But after integration with DFU, even during the sleep mode, i see a constant surge of over 2 mA. 

Could any of you guys let me know what can be the cause of bootloader taking in so much current? I found something in the forum which says that the bootloader has not been power optmized and has been considerably optimized in SDK 15.0.0 -> https://devzone.nordicsemi.com/f/nordic-q-a/36570/excessive-power-consumption-in-bootloader_secure_ble

But if i don't want to migrate to 15.0.0, is there a way this can be optimized for SDK 14.2? Please let me know. 

Thank you!  

[Simonr]

Hi

Do you see this current consumption when you're running the application or when the bootloader is running? There must be something keeping the CPU awake that causes this extra current consumption if you're running the application, as the bootloader shouldn't draw any excess current when it isn't active. Did you add any peripherals what so ever that might not be uninitialized properly?

In any case, I think it would be a good idea to migrate to the newer SDK, as the bootloader was not only optimized in current consumption but also in throughput in SDK 15.0.0. If you're interested, you can take a look at the migration guide here.

Best regards,

Simon

[SK]

Hi, 

If i just use bootloader, current consumption is around 2.3 mA. 

If i just use application, current consumption is 30 uA once i power it down. 

If i use bootloader + application, current consumption is around 2.4 mA once i power the device down. 

[Simonr]

Hi

SK said:

If i use bootloader + application, current consumption is around 2.4 mA once i power the device down. 

 And what is this number when the device is on? It seems way too high, and I don't think the bootloader alone is to blame. It must be causing something else to draw power as well (even though it shouldn't, as the bootloader and application are independent of one another). 

As for your "silly question", this should be fine actually. As long as you don't use bond-sharing in your application, and use the same SoftDevice version for the bootloader and application, it should not be a problem using different SDK versions for the two.

Best regards,

Simon

[SK]

Exactly! It is really high. This is when device is powered down. Switching off some peripherals as well in application to minimize the current.

By bond sharing, do you mean bond support? Yes, i am using that for buttonless DFU service.