Nrf9160 not setting requested active time

[PieterK]

Good day I am wondering if you can help me.

For background information.

Network - NB-iot

Firmware -  1.3.1

Software - Serial LTE Modem

Hardware - nrf9160dk

I am trying to set the requested active time down so that when I go into idle to save power and keep my IP connection that the modem doesn't stay active for 60 seconds there after.

The device is going into low power mode but only after 60 seconds. 

I will attach a screen shot of the AT-commands that I take to get to the point where I'd like to go into low power but the Requested Active Time does not change.

I came across this following link while attempting to get my power consumption down.

(+) turn off active time and go directly to power save mode - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

I tried the command AT+CPSMS=1,"","","10101010","00000000" to set the periodic TAU to 10 minutes and the requested active time to 0 and to 2 (00000001) seconds.

But they had no influence on the 60 seconds of high power consumption after issuing the AT#XSLEEP=2 to put the system into idle.

If anyone has any input as to where I am going wrong I will greatly appreciate it.

[Albrecht Markus Schellenberger]

PieterK said:

Thank you very much for all the help.

My pleasure, Pieter! I’m glad I can help :-)

PieterK said:

Here is the steps I took according to your steps.

What I can see in the log is that the modem:

(11:00:12.926) +CEREG: 1,"5209","09A53917",9,,,"00000000","10010100"

Successfully establishes a connection to the network.

(11:01:13.267) %CESQ: 255,0,255,0

Releases the active session and goes into idle. The delay from RRC connected to RRC idle is network specific and can not be affected by the UE.

(11:01:13.304) %XMODEMSLEEP: 1,599999

Is entering sleep mode directly afterwards.

Hence, the nRF9160 goes into PSM as soon as possible, which also is < 60s and that looks correct to me. If you perform the same steps with the Serial LTE modem application, do you get a similar result?

Regards,

Markus

[PieterK]

Good day.

Yes this is correct. Both At Client and the SLM do the same steps. Both enter idle after we issue idle command.

My main concern is that in these 60 seconds before going to low power we are consuming weeks worth of power. The nrf9160 modem consumes 20ma for these 60 seconds.

Can we cut down the 60 seconds as we have battery powered applications and we cannot afford that most of our power consumption is used by the modem after we are already finished. 

Our MQTT cycles last about 15 seconds. 

[Albrecht Markus Schellenberger]

Hello Pieter,

PieterK said:

My main concern is that in these 60 seconds before going to low power we are consuming weeks worth of power. The nrf9160 modem consumes 20ma for these 60 seconds.

Can we cut down the 60 seconds as we have battery powered applications and we cannot afford that most of our power consumption is used by the modem after we are already finished. 

Our MQTT cycles last about 15 seconds. 

I’m not sure if I can follow you here. Since the modem goes to PSM immediately, those 60s your are mentioning can not have anything to do with <Active Time> or PSM, unless the modem remains in RRC connected state (e.g. because of active MQTT transmission).

Otherwise, we are probably talking about Power Management of the application core or specifically Power saving for the SLM, which is a different thing as the modem is operating on a separate core.

Regards,

Markus

[PieterK]

Good day.

The 60 seconds will happen when the device has only been connected to the NB-IOT networks. By the time we issue the sleep command we are already disconnected from the MQTT broker.

We are just looking for a way to make the device go into idle (Keeping the IP connection) without having to wait 60 seconds after for the device to go into low power

(+) turn off active time and go directly to power save mode - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

I was following these steps to try and get the device enter the low power mode immediately. Those 60 seconds of high power consumptions is something we cannot handle. The device entering idle is taking more battery consumption that what our MQTT cycles are using.

We would like to be able to idle keeping our IP connection to just connect to the broker ,publish, disconnect and enter idle.

 

[Albrecht Markus Schellenberger]

Hello Pieter,

PieterK said:

We are just looking for a way to make the device go into idle (Keeping the IP connection) without having to wait 60 seconds after for the device to go into low power

My bad! Looking one more time at the time stamps, I now see that there is a 60s delay between:

(11:00:12.926) +CEREG: 1,"5209","09A53917",9,,,"00000000","10010100"

and

(11:01:13.267) %CESQ: 255,0,255,0

My apologies for overlooking that!

I actually might need a modem trace here to get some more details around what the modem is reporting internally. You can follow this guide to do so, but I would recommend you to use Trace Collector V2 preview instead.

Thanks & regards,

Markus