How to reach < 10 uA current in PSM mode with the nrf9160 DK?

RE: How to reach < 10 uA current in PSM mode with the nrf9160 DK?

Martin Lesund — Fri, 12 Jul 2019 06:51:39 GMT

Measuring PSM idle current on the nRF91 DK

RE: How to reach < 10 uA current in PSM mode with the nrf9160 DK?

slomusti — Fri, 12 Jul 2019 04:59:12 GMT

Dear Erienne, did you happen to be successful with the above work? Can you share some details please.

RE: How to reach < 10 uA current in PSM mode with the nrf9160 DK?

Étienne Castanié — Wed, 27 Feb 2019 09:24:59 GMT

Dear Martin,

Thank you for your detailed answer.

We started again working on the nrf9160 DK these days. Our main goal remains the same: compiling a working example that regulary sends data to a server (mqtt or http or else could even be SMS) then goes to sleep in PSM mode between transmissions.

If such an example is published please do not hesitate to tell us where we can find it.

We tried using the mqtt_simple example as you said. We ran into some issues with the latest master branches (similar to what this ticket describes https://devzone.nordicsemi.com/f/nordic-q-a/43366/nrf9160-mqtt-example).

We are currently trying to get mqtt_simple example working, then we will be able to test the modifications you suggested (using lte_lc_psm_req() or the AT cmds).

Best regards,

Étienne

RE: How to reach < 10 uA current in PSM mode with the nrf9160 DK?

Martin Lesund — Tue, 05 Feb 2019 14:32:49 GMT

Hi Étienne,

Since the asset_tracker is not yet power optimized, I would rather recommend you to use the simple_mqtt sample as a starting point.

The thing is that the PSM periods needs to be negotiated with the network, and also the idle eDRX periods:

1.use functions from the lte_link_control driver:

Function for requesting modem to go to PSM mode: lte_lc_psm_req()

Function for requesting modem to use eDRX. lte_lc_edrx_req()

For configuring the PSM values, you can set the CONFIG_LTE_PSM_REQ_RPTAU and CONFIG_LTE_PSM_REQ_RAT in the prj.conf file or directly in the SES IDE.

For configuring the eDRX values, you can set the CONFIG_LTE_EDRX_REQ_ACTT_TYPE and CONFIG_LTE_EDRX_REQ_VALUE in the prj.conf file or directly in the SES IDE:

2. manually with AT+commands:

I would advise you to set the Power Saving Mode (PSM) via this AT-command and then set the requested Extended Discontinuous Reception (eDRX) via this AT-Command.

You can add this into your application similar to how it's done in this "simple_at" sample.

And when measuring the current you should avoid having UART and such enabled to avoid additional current consumption.

RE: How to reach < 10 uA current in PSM mode with the nrf9160 DK?

Martin Lesund — Tue, 29 Jan 2019 09:56:11 GMT

Hi Étienne,

I am sorry for the delay.
[Note that the FW is not quite completed with regards to power optimizations.]

That being said you should be able to reach a much lower current consumption than you are measuring.

First thing that needs to be modified is the secure_boot application.

We need to disable the Serial Drivers

Or directly modify the "prj.conf" file by setting:

CONFIG_SERIAL=n

The "prj.conf" file is located in the same folder as where the CMakeLists.txt is located:

[Build and flash the new secure_boot FW]

Regarding the Asset_tracker sample, it is not power optimized to the fullest, so there may be some peripherals/clocks running in the background.

I need more time to debug and look at this. I will update this case.