Sara N211 SFF - Deep Sleep Current


I have some problems with the power usage of the Sodaq SARA N211 SFF. I tryed the WDT example but it only got the power down to 2 mA. Does anyone have more experience with this?



Might be a very simple answer, but have you checked if there are any LED’s enabled? I’ve had this issue for way too long without realising.

Yes, I checked that one. There are no LED’s enabled.

Have you tried uploading the serial passthrough sketch and putting in AT commands to get it into PSM manually?

I never boot or enable the SARA chip inside.


I would like to go into deep sleep mode for about one hour and then wake up and send some data but I’m having problems. The low power example watchdog sketch only sleeps for 8 seconds so I can’t use that and I have also tried the RTCZero library but the device seems never to wake up after rtc.standbyMode(). Has someone an example to share? I have been using USB as power supply.

Thanks for your help!


I use also the example of the watchdog sleep for 8 seconds and then I immediately put it to sleep again. Its awake for a very short time before it goes to sleep again. It is usable.


I made a note that we should make some easy to use low power examples.

We have a full working universal tracker with the sleep and wake on time.

For now Gabriel made some Autonomo RTC examples

And we have a low power sketch for the SFF here:

Best regards,

Hi all, I have experienced the same issue - Sodaq SARA SFF N211 rev. 2 without any sensors - upload low power sketch from your website and the device fall to 3,3 mA, not 20 uA.

I have also Sodaq SARA AFF N211 and there is NO problem with it.
Can you help what could be wrong, is it HW related?

Thank you.

Hi @Freisi ,

I have added the TX_ENABLE to the example code.

Best regards,

Hi @Jan,
thx, it is much more lower - now in sleep 15 uA.

So the high current in sleep was caused by the Low Power Bus Buffer Gate SN74AUP1G remaining powered ON?

For proper deep sleep it is necessary shut the bus buffer down before entering sleep and when wake up turn it back on for further communication with SARA module, right?

Thank you for your reply.

hey jan,
but still I am getting 2.4 mA even after TX_ENABLE LOW?
Could you please help.

Thanks a lot

Hi @Radheshyam_Singh,

Do you get 2.4 mA with your own sketch or with the low power sketch?

Best regards,

hey hi,
Sorry to disturb you again and again but I am not getting the current in the range of 3 micro ampere. I am using the same Low power sketch given by you.
Still I am getting the 2.4 mA.

What changes I can do ?

waiting for your reply.

Hi @Radheshyam_Singh,

What revision of the SFF are you using?
On the bottom of the board should be the revision number.

Best regards,

I am using Rev 3, and Rev 1. You can see in the Picture


I have tried each and every thing what you have suggested but still I am getting the same current that 2.4 mA using the low power sketch given by you. And I also did not get the POWER SAVING MODE.

Hope you can give me some positive solution.

Waiting for your positive reply.


Hey Jan,
Could you please reply me. Still I am struggling to get the PSM for SARA n211 module.


Are you compiling and uploading the low power sketch for the right board? AFF instead of SFF

Dear Kristofer,
Thanks for your reply, could you please tell me what’s the difference between SFF and AFF board ? I have all the AFF board. Do AFF board not have the PSM mode?