CSCON and GPS timer

[Alban THIERRY]

Hi,

I try to use CPSMS command to reduce the power consumption. The idea is to send a MQTT message every 10min and have the GPS coordinate every 5 min.

The NRF9160 is flashed with serial LTE modem and I communicate with him through AT command.

This is the list of command I send to NRF9160 :in bold the master command in none bold the response from the NRF9160

Ready
AT+CEREG=5
OK
AT+CSCON=1
OK
AT%XSYSTEMMODE=1,0,1,0
OK
AT+CPSMS=1,"","","10101010","00100001"
OK
AT+CFUN=1
OK
AT+CPSMS?
+CPSMS: 1,,,"10101010","00100001"
OK
+CEREG: 2,"E488","09343C10",7
+CSCON: 1
+CEREG: 5,"E488","09343C10",7,,,"00011110","11100000"
AT+CPSMS?
+CPSMS: 1,,,"10101010","00100001"
AT#XMQTTCFG="befc_gateway",600,1
OK
AT#XMQTTCON=1,"","","test.mosquitto.org",1883
OK
#XMQTTEVT: 0,0
AT#XGPS=1,0,300,290
OK
#XGPS: 1,1
+CSCON: 0

after 580s
#XGPS: 1,3
#XGPS: 1,2
+CSCON: 1
+CSCON: 0
+CSCON: 1
#XMQTTEVT: 1,-113
+CEREG: 0
+CSCON: 0

I don't understand why but the GPS timeout after 580s instead of 290s

I don't understand in the second CEREG response the Active-Time and the Periodic-TAU is not the same than the one I set with the CPSMS command. Did I configure something wrong ?

Also I'm not sure how the CPSMS command work. I don't understand how the MQTT can wake up the modem part and ask for a synchronization.

My ultimate goal is to reduce the power consumption and the consumption of data.

This the salae record of the At command exchange to check the timing : cereg and gps timer.sal

I hope my problem is clear,

Best regards,

Alban

[Charlie]

Hi Alban,

Kazi is not available temporarily. I will continue to help you on this ticket.

I don't understand why but the GPS timeout after 580s instead of 290s

This is properly a bug, but I need to do more test to verify, I will let you know when I figure out more information. 

Just in case you did not realize, GNSS and LTE can not work at same time on nRF9160, you can refer to https://docs.nordicsemi.com/bundle/ncs-2.7.0/page/nrf/device_guides/nrf91/nrf91_features.html#concurrent_gnss_and_lte for details.

I don't understand in the second CEREG response the Active-Time and the Periodic-TAU is not the same than the one I set with the CPSMS command. Did I configure something wrong ?

The actual Active-Time and Periodic-TAU values are decided by the network, you can check the with AT%XMONITOR command or +CEREG notification. 

+CEREG: 5,"E488","09343C10",7,,,"00011110","11100000" shows the network Periodic-TAU value is "11100000" which means PSM feature is deactivated on your network. You can check with your network operator to confirm.

My ultimate goal is to reduce the power consumption and the consumption of data.

This is quite general requirement for an IoT device, nRF91 is designed for this kind of application.

Alban THIERRY said:

I understand for the roaming, when you say modem sleep notification, is just the LTE-M that turn off or also the GPS ?

What is the difference between this method and send AT+CFUN=31 ?

AT+CFUN=31 Activates GNSS without changing LTE.  docs.nordicsemi.com/.../cfun_set.html

%XMODEMSLEEP set command subscribes and unsubscribes all types of modem sleep notifications. https://docs.nordicsemi.com/bundle/ref_at_commands/page/REF/at_commands/mob_termination_ctrl_status/xmodemsleep_set.html

 Best regards,

Charlie

[Alban THIERRY]

Hi Charlie,

To resume my project, I would like to have the GPS coordonate every 10min (for example) and send it in a MQTT.

Since the GPS and the LTE-M can't work together, I try to using CPSMS (to cut the LTE-M), but it don't seem to work.

What do you suggest ? What sequence of command I need to sent  to be able to do this ?

Best regards,

Alban