NRF9106 Long Running operations are not stable

[Sashi]

I have ran a test with the nrf9160-dk board. 

Setup:

PCA100900  0.9.0 pcb

NCS 2.0

Modem 1.3.2

App: ncs_v2.0.0/nrf/applications/serial_lte_modem

modification: change n->y   

CONFIG_NRF_MODEM_LIB_TRACE_ENABLED=y

 

Sim: tested with google fi, twillio, ibasis

Test:

Connected to cell network, verified everything is working OK and no issues over 24 hours. 

Wait 2-7 days 

Device does not respond to AT commands, can not get Modem Trace from the device (may be other issue with app?) .  

Device is not connected to the network. 

Press reset on the PCB. 

Device will respond to AT commands

AT+COPS=?, AT+CFUN? and similar commands don't result in connecting to the network. 

Power Cycle DK board (toggle on/off switch): remove USB and reconnect USB. the board will reconnect to the network and work correctly. 

[helsing]

Hi Sashi,

We will try to reproduce this ourselves with the same DK version.

Have you seen the behaviour with any other hardware than this particular DK version?

[helsing]

Could you please share the whole log file from LTE Link Monitor? Click on "Open log file" as shown below, and store the file.

Could you please also collect the modem trace from when your board stops responding?

Please note the following from the modem firmware v1.2.3 changelog :

• Note that this modem firmware is targeted nRF9160 SiP Revision 2 
• It can be used for nRF9160 SiP Revision 1, but only for testing and development

This means that the firmware might work but it is not tested and unexpected errors can be seen.

We are setting up an additional DK with an nRF9160 SiP Revision 2, in order to see if we experience any issues.

Another thing to try is to connect another UART to the the nRF9160 DK via some of the other pins that are configured as a UART. That way one could try to see if the SiP responds.