Is there a way to truly hard reset the nRF9160 without power cycling?

[GJSea]

Hi,

We have several hundred devices in real time deployment and find the typical DNS/Cellular connectivity issues during the day that we generally solve with delayed connection retries, up to and including ultimately resorting to automatically soft-rebooting using sys_reboot(SYS_REBOOT_COLD) that typically resolves the 'outage' issues.

However in some instances there's no amount of programmed rebooting that works, and only a battery disconnect+reconnect that instantly solves the connectivity issue. Is there some internal state in the modem firmware that is maintained across a soft reboot, does sys_reboot actually reboot the modem firmware, or cell tower association/mapping that is keeping some old state that only a full power cycle solves? Is there a way to fully reset the nRF9160/reboot the modem firmware as though a full power cycle occurred, or do we need to design a full de-energizing circuit for our motherboard?

Thanks! 

[Sashi]

So We are seeing something similar. where a sys_reboot does not recover the device.  But simply cutting power and re powering restores the device instantly. 

The device can stay connected for say 10-12 hours, but if there is an issue, the device can sys_reboot all day long after timing out over and over again. But the second the device is power cycled it connects and starts working again like nothing is wrong. 

There must be another command that allows your to restore the modem state the same as coming out of a power cycle.  

[GJSea]

Agreed, there's a definite flaw in the system if we're both seeing this. Didrik Rokhaug any more ideas what might be going on in our situations, whereby a power cycle immediately addresses the connectivity issues the SOC experiences?

[Sashi]

I tried using sys_power(1)   as well as toggling the with 

AT+CFUN=4  and 

AT+CFUN=1  

I do have a theory that perhaps the sim card gets to a weird state, and the resetting the sim card is needed with a 

AT+CFUN=4 command. but I have not idea what the modem code is doing, so just taking stabs into the black box and hoping for a good result. 

[Didrik Rokhaug]

Hi Sashi,

As I said in my previous reply to GJSea, I will need a modem trace to be able to look further into the cause of the lock ups you are seeing.

Please also include which SDK and modem FW versions you are using, as they might not be the same as it was a year ago.

Best regards,

Didrik

[Stratosphere]

It seems the issue is still there with modem fw. 1.3.4

after a certain number of connects/disconnects the modem is not able to connect at all, even after waiting for hours and trying again and agian with a few seconds/minutes gap in between. A hard power reset fixes the issue right away.