DFUButtonless consume power?

[nghia]

Hi,

I'm using NRF52832 with s132 softdevice for a low power project. I notice that when running firmware with DFU Buttonless, the SoC consume more power than without it.

I refer ble_app_buttonless_dfu example for my firmware. From my understanding, ButtonlessDFU is enable when calling bleDfuButtonlessAsyncSvciInit().

My question is:

- Does ButtonlessDFU truely consume more power than just flash using IDE?

- Is there any way to reduce power when using Buttonless service?

Thanks a lot for helping!

[Sophisti]

nghia  and srac  we have the same problem. Have either of you been able to solve this issue and if so how?

[Vidar Berg]

There can be a number of reasons for the increased current consumption. Anything from forgetting to turn off logging over UART to having an assertion in the code. Have you measured the idle current in your case? If so, did it increase after you enabled the buttonless service?

[Sophisti]

The firmware without buttonless is around 20 uA and with buttonless is around 2 mA. But in both situations the firmware works as intended. Logging is off that is certain. 

What is the VSCI interface they mention maybe that is the solution?

[Vidar Berg]

SVCI interface allows the main application to make calls to functions inside the bootloader. It is currently used to let the application change the adv. name to be used when the bootloader starts up in DFU mode: Setting new advertisement name. But I don't see how this could lead to the increased current consumption. 

Is 2mA the average current draw, or is it the idle current? Also, did you make sure to exit Debug Interface mode before you conducted the measurements (you can power-cycle the board after programming to ensure this)?

[Sophisti]

It is the idle current draw that is the problem. The 'spikes' you see is are BMA400 I2C event. But without Buttonless firmware the nRF52805 goes to sleep and draws 10-20 uA.

UART and Debug is turned off. 

[srac]

I blieve problem was the bootloader's UART. I forgot to change bootloader's sdk_config.h according to project

[Vidar Berg]

Thanks. However, the SDK bootloader should always reset the UART before entering the main app(). Also, the idle current with UART RX enabled should be in the 1 mA range, not >2 mA as shown in your measurement.

Do you continue to receive data from BMA400 as before? I'm asking because your idle current is similar to what it would be if the TWIM was stuck in receive mode for some reason (with LDO regulator).