nRF9160 persistent socket in eDRX

RE: nRF9160 persistent socket in eDRX

user2115 — Thu, 02 Jun 2022 13:23:13 GMT

Hi,

Normally you'd let poll time out, as there's not much else that can interrupt it, except when there's activity on the socket itself.

I do not see any immediate way to interrupt it mid-sequence other than the above, except maybe closing the socket (which should give you a POLLNVAL)? I suppose you could try to call poll sequentially, ie. split it up into 20*1min timeouts?

Kind regards,

Håkon

RE: nRF9160 persistent socket in eDRX

user108651 — Wed, 01 Jun 2022 19:47:36 GMT

Hi Håkon,

I know it's been a couple months since my last response. The poll is working great to have the nRF9160 in a low power mode.

Currently I have the poll with a 20min timeout running in a thread. I have a scenario where I would like to interrupt the socket poll so it will stop listening. What is the best way to do this? Is there a signal I can send to the poll? The sdk code says poll is based on this command:

https://pubs.opengroup.org/onlinepubs/9699919799/functions/poll.html

One of the comments is this:

poll() shall block until a requested event occurs or until the call is interrupted.

How do I cause this [EINTR] to occur or is there a better way to interrupt the poll?

Thanksfor your help,

Chris

RE: nRF9160 persistent socket in eDRX

user2115 — Wed, 30 Mar 2022 08:51:34 GMT

Hi Chris,

Yes, that is correct.

Kind regards,

Håkon

RE: nRF9160 persistent socket in eDRX

user108651 — Tue, 29 Mar 2022 15:05:19 GMT

Great, thanks Håkon. I'll test out using poll.

I'm not using MQTT, but based on the code it looks like I can simply do a recv after the poll to get my data. Is this correct?

if ((fds.revents & POLLIN) == POLLIN) {

err = recv(fd, recv_buf, length, 0);

// handle error or data here....

}

Thanks for the help,

Chris

RE: nRF9160 persistent socket in eDRX

user2115 — Tue, 29 Mar 2022 08:44:44 GMT

Hi,

[quote user=""]How do I know something is available for me to process? Do I have to keep polling with a socket receive command?[/quote]

You can use the poll() function, similar to what is done in the mqtt simple sample:

https://github.com/nrfconnect/sdk-nrf/blob/main/samples/nrf9160/mqtt_simple/src/main.c#L622

[quote user=""]That seems like it would eat up my battery. Recommendations on how I should best approach this for low power would be great.[/quote]

poll() itself will not eat your battery. It is the responsiveness of your link that consumes power

Have you looked at the power calculator for nRF9160? https://devzone.nordicsemi.com/power/w/opp/3/online-power-profiler-for-lte

Please note that if your device is TX oriented (ie. you drive the communication), I'd recommend that you use PSM instead and send data on-demand instead.

However, if you expect to receive data from a server, eDRX would be wise to use.

Kind regards,

Håkon