SIM selection on nRF93M1 DK

[Jon Arne Pedersen]

Hi,

On the nRF93M1 DK, we can switch between physical SIM and eSIM with %SIMCFG="SimSlot" (mfw 1.5.0).

1. Is SimSlot written to NVM on set, or in the flush at CFUN=0?
2. Does every CFUN=0 write NVM anyway?
3. Are two writes per power-on acceptable over a 10-year life?

Regards,
Jon-Arne Pedersen

[Simon D-M]

Hi,

Is SimSlot written to NVM on set, or in the flush at CFUN=0?

Yes, this configuration is even kept through power cycles.

This is easily testable. You can send the %SIMCFG="SimSlot",1 to set the slot to 1, perform any other command or test you want to check, and then finally read back the SIM configuration with the %SIMCFG? command.

Does every CFUN=0 write NVM anyway?

I must say that I'm not fully familiar with the nRF93M1 yet, but from what I was able to test, it seems like +CFUN=0 does write to NVM.

Are two writes per power-on acceptable over a 10-year life?

How many power-on do you expect in the lifetime ?

Best regards,

Simon

[Jon Arne Pedersen]

Thanks, yes, SimSlot writes to NVM in my test.

Normally, there won't be many power-on in the lifetime, but there will always be outliers and problematic devices that may power-cycle every day or even several times a day.

To avoid the NVM writes, I see two alternatives:

1. SIM holder with a detect line to the host
2. SIM1_DET level readable via an AT command

I don't see the second in mfw 1.5.0 (AT+CLAC). Is it supported or planned? If not, what is the rated write endurance of the modem NVM?