RF channel frequency settings for S2LP

[H..10]

I am in the process of migrating from spirit1 to S2LP, I am stuck in the calibration of the frequency, before in spirit 1 it is mentioned in the datasheet of spirit1 via equation 3 

• fc=fbase+foffset+(fxo/2^15  ×CHSPACE)×CHNUM

On the other hand in the S2LP datasheet in equation 6 it's mentionned =>

• fc=fbase+(fxo/2^15  ×CHSPACE)×CHNUM

So I want to know where is the foffset on the S2LP equation 6

[Winfred LU]

The offset frequency is a correction term which can be set to compensate the crystal inaccuracy after e.g. lab calibration.

Please refer to equation 7 -

foffset = (fxo / 2^18) * FC_OFFSET

where:

FC_OFFSET is a 12-bit integer (expressed as 2's complement number) set by the FC_OFFSET[1:0] registers

[Winfred LU]

For S2LP, the frequency offset is not calibrated with registers. So foffset is not shown.

[H..10]

Thanks for your reply Winfred, so if the frequency offset is not calibrated with registers, is there a software workaround to fix this issue ? it means is there an alternative solution ?

[Winfred LU]

The crystal shall be calibrated in hardware.

Then the compensation can be done firmware, by measuring frequency differences on a generating single wave and configure accordingly.

This is used for most communication protocols such as Sigfox.