nRF9160 Low Power Example

[GNotman]

Hi,

I'm currently trying to evaluate the nRF9160 for one of our projects.

One key requirement is the power consumption when using eDRX.

I have tried profiling the at_client sample, but the lowest I've manged with the nRF9160DK is about 900uAs.

Additionally, the power profile does not seem to show the expected paging windows when eDRX is configured.

Is there any low power example, or documentation which can help me with this?

[Håkon Alseth]

Hi,

 

I have tried profiling the at_client sample, but the lowest I've manged with the nRF9160DK is about 900uAs.

Most of this is due to the UART RX being enabled, which will keep the peripheral clock tree running in sleep. Disabling the UART will lower the floor current, but will also make this specific example non-working.

Is there any low power example, or documentation which can help me with this?

Unfortunately, we do not have a power optimized example showing the lowest consumption possible at this stage in the engineering phase. The closest is the asset_tracker example, where you can enable power optimization (PSM or eDRX), but you will also need to tweak other parts, such as disabling serial in both secure_boot and the application itself.

 

Kind regards,

Håkon

[GNotman]

Hi Hakon,

Here is the output from the profiler I am using.

The first image shows an average current of ~860uAs between the eDRX paging windows. You can also see the initial registration activity and the regular eDRX paging windows:

The second image is after using (CONFIG_SERIAL=n) with secure_boot and the same modified version of asset_tracker as used above. It is clear that the boot loader fails to load the main firmware:

[Håkon Alseth]

Hi,

 

GNotman said:

The first image shows an average current of ~860uAs between the eDRX paging windows

As you're using a more accurate AM-meter than I am, I'll trust your base current better than mine. My cheap am-meter shows approx. 1.0 - 1.2 mA between the wake up's.

Something is powered during these events that shouldn't be powered. As mentioned, we are actively looking into this issue internally.

GNotman said:

The second image is after using (CONFIG_SERIAL=n) with secure_boot and the same modified version of asset_tracker as used above. It is clear that the boot loader fails to load the main firmware:

Try cleaning your build directory after changing any configuration in the project file. Not sure what happens here, but it looks like a fault given the constant current consumption.

If you are in debug mode, it might be this errata: https://www.nordicsemi.com/DocLib/Content/Errata/nRF9160_EngA/latest/ERR/nRF9160/EngineeringA/latest/anomaly_160_17

Kind regards,

Håkon