nRF9160 PSM active time strange behaviour

RE: nRF9160 PSM active time strange behaviour

tomhen — Thu, 17 Feb 2022 16:36:35 GMT

Right now I am using an almost unmodified version of the UDP sample application. I have changed the proj.conf to modify transmission interval and server address, and to set up the desired PSM configuration and modem tracing. The only change in main.c has been adding some text to the data being send over UDP. I attach both files to the message. The server I communicate with is currently unavailable, but I tried using the default "8.8.8.8" Google server and obtained similar results.

devzone.nordicsemi.com/.../4645.prj.conf devzone.nordicsemi.com/.../662818.main.c

Best regards,

Tomás

RE: nRF9160 PSM active time strange behaviour

JONATHAN LL — Thu, 17 Feb 2022 15:05:08 GMT

I dont think there should be any TCP traffic so this is strange, what modifications have you done to the UDP sample?

Regards,
Jonathan

RE: nRF9160 PSM active time strange behaviour

tomhen — Thu, 17 Feb 2022 10:44:12 GMT

Hi Jonathan!

I turned logging on and looked at the trace output with Wireshark. I can see that after sending data the modem receives a random amount of unintended TCP packets from several different sources. If this reception happens to be under the Active mode it triggers the modem back into RRC_CONNECTED state, as expected. I have no idea why these inbound TCP packets are being generated, but they would really impact the power consumption of my application. I attach the RAW and PCAP modem traces.

devzone.nordicsemi.com/.../trace_2D00_2022_2D00_02_2D00_16T16_2D00_14_2D00_57.136Z.bin devzone.nordicsemi.com/.../trace_2D00_2022_2D00_02_2D00_16T16_2D00_14_2D00_57.136Z.pcapng

Best regards,

Tomás

RE: nRF9160 PSM active time strange behaviour

JONATHAN LL — Tue, 15 Feb 2022 11:57:14 GMT

I want to specify that the Active timer is not the exact same as iDRX.

Looks like you are paging is happening so i would check if the log provides the same time windows as the spikes in the current measurements. You should be able to see what values matches form the current draw and the timer values.

RE: nRF9160 PSM active time strange behaviour

JONATHAN LL — Mon, 14 Feb 2022 15:46:16 GMT

Might look like PSM is not happening, can you turn on logging?

Regards,
Jonathan