Vehicle Tracker NRF9160 Radio Sometimes hangs, we have initiated a nightly reboot which uses alot of battery. How can we avoid the radio hanging?

[crotberg]

We have designed a vehicle tracker that uses the NRF9160. We have found in the past that sometimes after the radio has been running for a while it gets into a loop where it becomes unresponsive, basically a loop where it doesn't receive messages.  We have to reset power to get it to work again. We are using the Asset Tracker 2 as our base code.

We added a nightly reboot to try to refresh the radio every night before it has a chance to hang. I was told that this solution can be bad for battery usage.

What are the best practices for the NRF9160? Can just the modem be reset if needed?

Thank You

[dejans]

Hi,

How many devices do you have? On how many devices have you noticed hanging behavior?

We have found in the past that sometimes after the radio has been running for a while it gets into a loop where it becomes unresponsive, basically a loop where it doesn't receive messages.

Can you provide more details about the loop and unresponsiveness? What kind of loop and unresponsiveness have you observed?

We have to reset power to get it to work again.

How often do you perform reset? Is one reset enough to bring device to life? Does the device become unresponsive again and if so, when? Do you need to perform reset every time device hangs?

We added a nightly reboot to try to refresh the radio every night before it has a chance to hang.

How do you perform this nightly reboot?

What are the best practices for the NRF9160? Can just the modem be reset if needed?

Modem can be reset using nrfxlib API. You can look at nrf_modem_shutdown() which deinitializes modem library and turns off the modem and nrf_modem_init() that initializes the library and turns on the modem. You can also put the modem to desired functionality using CFUN set command. Please be aware that it is possible to activate reset loop restriction. You can read more about modem behavior in that case in the documentation. 

Best regards,
Dejan

[crotberg]

It was just a couple when we were in beta. We just rebooted the power on the device and it worked. We add watchdog and it mostly fixed the issues. 

I will review the best practices, is it best to reset the modem and scheduled interval?

Thank You

[dejans]

Hi,

crotberg said:

I will review the best practices, is it best to reset the modem and scheduled interval?

There might be various reasons when modem reset is needed. It is generally recommended to de-initialize the modem gracefully using +CFUN=0. Another consideration is the existence of potential reset loop. You can read more about the process of activating reset loop.

Is it that you want to do modem reset on scheduled interval only to remove unresponsiveness, otherwise you would not do it normally in your application?

Best regards,
Dejan

[crotberg]

Thank You

We don't want the unit to become unresponsive because we have no way of resetting it manually

[dejans]

Hi,

I was just thinking about potential underlying issue that is causing unresponsiveness. If the reset is doing the job for you and does not have any negative impact on your application, then it might be fine. 

Best regards,
Dejan