The "S2-LP bring-up good practices v1.0.pdf" [1] document states the following information regarding AFC:
"AFC_CORR is 2-complement byte (signed). Granularity is 508Hz for 50MHz Xtal"
The mentioned step size of 508 Hz for a 50 MHz oscillator also corresponds to my practical observations.
The following information can be found in the datasheet:
[..]
Fdig/(3*(2^13)) where Fdig is the frequency of the digital block (24, 25 o 26 MHz).
1 LSB is:
At 24 MHz: 976.5625 Hz
At 25 MHz: 1017.25260416 Hz
At 26 MHz: 1057.9427083 Hz
[..]
Since Fdig corresponds to 25MHz for a 50MHz oscillator, the AFC_CORR step size would therefore be 1017Hz.
This doesn't match the actual results or the information in the mentioned PDF.
What is the correct formula to calculate the step size for all oscillator frequencies?
Thanks
~Matthias
[1] https://community.st.com/t5/interface-and-connectivity-ics/frequently-asked-questions-on-st-s2-lp-sub-1ghz-transceiver/m-p/736882/thread-id/11431?attachment-id=28318
