SARA pin 2 marked as 'Reserved' but used in schematic

Hi @Jan and others!

I’m currently working my way through the documentation on the SARA R410M module. According to it’s datasheet pin 2 is Reserved. Looking at the SODAQ SARA R410M Board’s schematic I noticed a 200k resistor connecting to pin 15. The schematic shows that pin 15 is reserved as well, but looking at the datasheet I found out pin 15 is the PWR-ON pin. I felt creative and fotoshopped the schematics to show the correct pin names.

This still makes me curious as to what pin 2 is used for, I have no clue. Does anyone here have a good guess?


Hi @M.Bend,

Thanks for updating the pin names.
I have send this to our hardware engineers.

Best regards,

Hi @M.Bend,

Apologies for the confusion on the pin-names, we tried to keep one footprint/schematic-block for several modules (e.g. SARA-G350, SARA-U270, SARA-N211, SARA-R410, SARA-R412). But as you might’ve noticed, this gets confusing quite quick (maybe even more when everything is called RSVD). I’ll discuss this with my colleagues and see if we can make this a bit more clear (in future revisions).

As for pin 2, this is used on the 2G/3G-modules (e.g. SARA-G3, SARA-U2). This is V_BCKP and is typically used as Real Time Clock supply input/output (you can check more here:, page 18/19).

Hope this clarifies it a bit!

Thanks for the info @Gregory! Luckily I’m using the R410M. So I’ll have pin 2 floating. Thanks for the quick response!