PSM TAU and AT

RE: PSM TAU and AT

Mohammad Amin — Sun, 21 Jul 2019 19:02:07 GMT

Thanks. I used other sim cards and it seems they enter PSM mode.

RE: PSM TAU and AT

Carl Richard — Fri, 05 Jul 2019 12:55:50 GMT

Hi Mohammad!

We just ran into a somewhat similar issue, it's not resolved yet, but I can maybe provide some helpful info! We also use the iBasis card and have discovered that it forces the <Requested active time> value to 0, effectively disabling PSM.

You can check if there is a difference in the PSM modes of your different providers by using the AT command AT+CPSMS? after activating PSM. (as stated in the AT Command documentation). It will return the parameters used.

Hope you can utilize this!

For reference: we are situated in Norway, so it could be a different situation.

- Carl

RE: PSM TAU and AT

Mohammad Amin — Thu, 20 Jun 2019 20:57:12 GMT

Hi, Thanks for responding.

1. I am using MQTT_simple example and I added "err=lte_lc_edrx_req(true)" to it right after "modem_configure" function. This example uses polling in a while loop to see if any data is received or not.

Does the device wake up from PSM after each polling? Do I need to enable PSM after each polling again?

I tried to enable PSM after each polling and then go to sleep using " k_sleep" and "k_cpu_idle", however, my power consumption has increased. I guess because every time for requesting PSM a large power is consumed. In this case, what are my options? Is only calling "err=lte_lc_edrx_req(true)" once before the while loop enough or I need to call it every time after each polling?

I checked this link and nmeasured the current based on the instructions and it works for me, however, in this tutorial in order to reduce the floor current, the serial peripheral has been disabled both from SPM and the main project. But I want to disable serial and other peripherals in the code whenever I want because I may need to interact with other sensors once in a while and therefore for that time I need the serial to be on. Is this possible to disable serial through the code and then go to sleep? I read this and this topic and it seems other ones want to disable the peripherals in the code too and no one answered them.

2. Thanks for the clarification.

3. Both HOLOGRAM and iBASIS connect to the same network(Rogers in Canada) but their power consumption is completely different and HOLOGRAM shows a lot less power consumption.

RE: PSM TAU and AT

Sigurd — Wed, 19 Jun 2019 09:28:36 GMT

Hi,

For measuring current in PSM mode, I would recommend taking a look at this blog post.

The TAU is a mandatory procedure to do after waking up from PSM.

If you start to send data, while in PSM mode, the device will wake up from PSM.

Also note that some networks does not support PSM yet!

[quote user=""]I also am not sure about the role of AT too[/quote]

What do you mean ? the role of AT commands ?

[quote user=""]through LTE or LTE-M?[/quote]

The system mode is either NB-IoT or LTE-M, see this link.

[quote user=""]a lot more power consumption than the HOLOGRAM[/quote]

How much difference ? Also see this comment. Are you on the same network for both sim cards? If it's a different network operator with the HOLOGRAM sim, it could be that only that network support PSM ?