Is there some mechanism to subscribe to unsolicited modem responses?

[Richard W Mincher]

SDK 2.0.0, nrf9160, modem fw 1.3.2

We are effectively running the GNSS sample and the MQTT sample in separate threads.  We are interested in seeing the modem temperature (via AT%XTEMP=1 command).  This command seems to enable periodic notifications of the form %XTEMP: N,M

Is there a way for one of my threads to register a "callback" that is executed when the %XTEMP string is received from the modem and delivers that %XTEMP: N,M to me?

We saw the nrf_modem_at_cmd_filter_set, but that looks like it is intercepting commands going to the modem rather than processing responses from the modem.

Thank you.

[Hakon]

Hello,

I believe the AT monitor library is the closest thing to what you are asking for. It should be pretty straight forward to use it for XTEMP, as far as I can tell.

[Richard W Mincher]

Yes, it does seem like AT monitor is what I am looking for.  We started with the AT Monitor sample and it ran showing us the +CEREG and %CESQ messages.

We modified it by adding another AT_MONITOR() for "XTEMP" (the monitor library uses strstr() for filtering) and did a nrf_modem_at_printf("AT%%XTEMP=1"); to enable perioding reporting.  This returned "OK".  We never saw an XTEMP message.  We even tried changing the AT_MONITOR filter to ANY.  And we enabled debug messages in the AT monitor library -- it never received an "%XTEMP" message from the modem.

Does the modem ever send those %XTEMP notifications?  It doesn't seem to.

Thank you.

[Hakon]

Richard W Mincher said:

Does the modem ever send those %XTEMP notifications?  It doesn't seem to.

A notification is sent when the temperature is rising above a high or critical temperature level or cooling down from a critical or high temperature level.

So if the modem temperature doesn't change much at all, it's possible that the modem will never send a notification.

[Richard W Mincher]

The documentation seems to imply that the reporting frequency is approximately 60 seconds and that it may report more frequently if it gets closer to a critical threshold.  I find it hard to believe that it 1) doesn't give an initial report when it is turned on, and 2) it never reports unless it changes severely.  I can believe that the update frequency is dependent on the proximity to a critical threshold.  I can try hitting it lightly with a heat gun or some freeze spray, but I would have expected in the minutes that I waited for a report that I received nothing.

Are there periodic reports (other than +CEREG and %CESQ) that I can see?  I would have expected that by setting the filter to ANY (NULL) I would see other things that other system components were watching.

Thanks.

[Hakon]

Richard W Mincher said:

Are there periodic reports (other than +CEREG and %CESQ) that I can see?  I would have expected that by setting the filter to ANY (NULL) I would see other things that other system components were watching.

Have you enabled any other notifications? The modem won't send notifications unless you subscribe. That includes the AT%XTEMP=1 to subscribe to temperature notifications.

I don't have access to equipment until Wednesday, but if you wait I can try to test this myself.

[Richard W Mincher]

I would love to see what you find.  We did send  AT%XTIME=1 and did get one single response from that.  I would expect that it would get this at some infrequent rate as well -- or maybe each time the LTE network connects at a minimum.  Still nothing with AT%XTEMP=1.

If we were to poll the battery and temperature, what is a reasonable rate to do this without interfering with performance?  Is that too often if I send a %TEMP every minute?  Clearly, under normal circumstances, the temperature would not move quickly.  2 minutes?  Thirty seconds?  5 minutes?  I would like to have a relatively current reading to report whenever the client application requests it but don't want to unnecessarily choke the modem pipe.

Thank you.