Hello,
As mentioned in the subject, I am currently working with an LTE EVB Kit baseboard along with a BG96 modem.
Lately, I’ve been experiencing inconsistent behavior when attempting to enter PSM (sometimes it works, sometimes it doesn’t). However, it’s important to note that I’m working on a cellular network that has only recently started implementing PSM, so many of the failures may be due to the network itself rather than the modem.
That said, the main question of this post is: what physical procedure should be performed on the LTE EVB Kit to ensure proper entry into PSM (assuming the network is fully optimized for PSM)?
I was considering that the modem might not be entering PSM because a trigger pin is held high. While reviewing the LTE EVB Kit user manual, I found a pin named WAKE_IN on connector J805, which could potentially be high. Currently, nothing is connected to that pin, but in electronics, it’s common for a floating pin to act like an antenna and unintentionally remain high due to ambient noise. This could explain the inconsistency in the tests. Therefore, I was thinking of grounding this pin to ensure it stays LOW.
The issue is that I haven’t found enough information to confirm whether this connection is safe for the baseboard.
Another interesting point is that although there is a dedicated pin on the EVB Kit to wake up the modem called WAKE_IN, this pin is not defined in the BG96 hardware design. If one wants to wake up the modem via pins, the only requirement is to pull the PWRKEY pin low (essentially using a jumper on connector J302 of the EVB Kit). This makes me uncertain about the actual purpose of the WAKE_IN pin in this context.
P.S. I also reviewed the document Mechanism and Application Reference for PSM and Sleep Mode of NB-IoT Module, but I couldn’t find relevant information for my use case.
Thank you in advance.
