nRF9160, mfw 1.3.2 - power consumption in eDRX - realistic value / demonstration?

[Achim Kraus]

Reading The adhoc smart waste solution uses the nRF9160 SiP I tried to reproduce the mention 6 µA with LTE-M in eDRX with an interval of 655 s.

I use

CONFIG_LTE_EDRX_REQ_VALUE_LTE_M="1011"

CONFIG_LTE_PTW_VALUE_LTE_M="1111"

and these values are reported in LTE_LC_EVT_EDRX_UPDATE, "eDRX: LTE-M 655.36 [s], page 20.48 [s]".

Using a nRF9160-DK, v1.1.0, with NCS 2.1.2, mfw1.3.2  (suspended UART, wakeup on io level interrupt), my PPK II shows 31 µA.

Using PSM with the same device and application goes down to 3.7µA (UART suspended, wakeup on io level interrupt), so for me it seems to be the modem part, which consumes more. That's not too bad, but what is required or what is the precondition for 6 µA ?

I already searched the forum and others seems also to stick to larger values  nrf9160 psm and edrx mode power consumption test (117µA) and I failed to find the hint, how to get it down to the 6 µA.

[Achim Kraus]

I recognized, that the SIM card stays active (P30 1.8V).

With PSM, it shutsdown (0 V).

I tried "%XDATAPRFL=0", but that doesn't help. Very strange, that PSM switches it off, but eDRX not.

[Achim Kraus]

I found:

how to select buy an edrx low power capable sim card for the nrf9160

that mentions:

> From what I've heard, SIM cards with this feature enabled are not commercially available.

and it mentions also

> the file EFad in the SIM card controls UICC deactivation during eDRX. 

> AT+CRSM=176,28589,0,0,0

reports

> 144,0,"00000002"

so bit 4 in byte 4 is 0 => my UICC doesn't power off for eDRX.

[Øyvind]

Hello! 

I will look into your issue and get back to you on Thursday. 

Kind regards,
Øyvind

[Øyvind]

Hello, sorry for the delayed answer.

The numbers presented in the article are numbers from the nRF9160 product specification as far as I can tell. Can you do measurements with your PPK2 and provide the logs to us? Please measure during idle eDRX and also try measuring the SIM as well. 

What kind of application are you running?

Kind regards,
Øyvind

[Achim Kraus]

> Can you do measurements with your PPK2 and provide the logs to us? Please measure during idle eDRX and also try measuring the SIM as well. 

I did that measurement already. My conclusion after I detected, that my SIM card didn't switch off in eDRX (1.8V at P30), is that my power consumption (31 µA) mainly results from the SIM card (and a minor contribution from the DK).

> From what I've heard, SIM cards with this feature enabled are not commercially available.

I guess, that's my issue. If such SIM cards, which are switching off for eDRX are hard to get, I have to live with the current for the SIM card + modem.