I want to compute the resonant circuit formula to have the right value for C :
I use the STEVAL-ISB039V1 kit with transmitter and receiver board
First mistakes with inductive and capacitors values :
If I use the fomula for resonant frequency :
Fd = 1 / ( 2 * pi * racine ( L1 * ( 1 /( 1/C1 +1/C2 ) ) ) from STM STWLC03 datasheet, page 49/56
with the kit values : L1 is 12.3uH and C1= 304nF, C2=3.3nF
L1+C1+C2 form a serial circuit and 1 / (1/C1 + 1/C2) is a basic formula to have Ceq from 2 Capacitor in serial..
But Fd gives : 794 KHz !! (I use the kit's values !)
If I compute the transmitter Fs I have 138KHz (That's the right value I think..)
Do you have any idea about the mistakes ??
My goal is to change the Rx antenna and compute new capacitor tuning value at receiver side, but first, with kit's value I don't have the right value..
Thanks you for your help