SIM7000G Power Saving Mode (PSM)

Jonas Fleck

Hi together :-)

Did anyone got the Power Saving Mode of the SIM7000 to work?

If I send the following commands the device is sleeping after a few seconds.

AT+CSCLK=1
AT+CPSMS=1

The Problem is that when I pulldown the power key pin of the SIM7000, the devices wakes up as expected but the connection is lost and needs to be reestablished which produces unnecessary traffic.

Is anyone facing the same issue or has a solution?

afzal_m

@jonas-fleck

I’ve reached out to some colleagues who might have an answer on this one. Will keep you posted.

afzal_m

@Jonas-Fleck

One of my colleagues did a test with the same device. He confirmed that this issue was not observed during our testing. Tests in our lab were performed with an evaluation board, which had a little momentary switch connected to the pwrkey pin on the module. When the device was sent to PSM and then the button was pressed, the device woke up and was able to connect to the cell just by raising an RRC connection, the attach and PDN connection were always maintained.

My colleague wonders if the issue has something to do with the fact that you have sent the device to slow clock mode (at+csclk=1) before sending it to PSM…

Jonas Fleck

Hi @afzal_m,

thank you so much (and of course your colleagues) for your efforts.

Indeed the SIM7000 stays attached to the cell but the PDN/PDP context is lost. Before the modem enters PSM, it deactivates the PDP context, which is logged via the Serial connection.

Maybe you can ask you colleagues for a short example of how to maintain the PDN/PDP context during PSM? In certain forums a lot of users are facing the same problem.

What I have done:


...General config

# Start PDP Context
AT+CIICR

#Receive IP
AT+CIFSR

#Connect to iotcreeators
AT+CIPSTART="UDP","172.27.131.100",15683

...Send Data

After a few seconds the device enters PSM and sends the following notifications:

+PDP: DEACT

+CPSMSTATUS: "ENTER PSM"

Maybe I just forgot one setting to tell the modem to keep the PDP context active?

Edit: After sending

AT+CIICR

after leaving PSM, the device gets the same IP-Address and the connection is established fast enough for me :)

I have read in your guidelines that you want devices do not reestablish PDN contexts within two hours. I just want to fulfill that requirement :) So reconnecting after leaving the PSM is not my preferred way to go…

afzal_m

@jonas-fleck

Could it be that this is just a message from the Qualcomm chipset which is displayed every time when the module enters PSM?

It doesn’t really mean that the device has closed the context.

One of my colleagues has observed the same behavior on the BG96 which relies on the same chipset and always displays a similar message when it enters PSM.

Jonas Fleck

@afzal_m

I thought the same because the device always gets the same IP address.

But anyway I have to execute the commands for connecting, receiving the Ip, and opening the udp connection every time the device wakes up, which feels a little bit wrong because the context should already be opened.

afzal_m

I am running out of ideas then :-(

Do you have access to the support teams of Simcom maybe?

Jonas Fleck

@afzal_m

Ok then I will go the hard way :)

The electronic lab of our university owns a spectrum analyzer. Next week I will try to investigate which command produces traffic and which not :)

Im a little bit overcorrect in building clean solutions. Sorry for consuming your time :)