CC1312R: Frequency change related questions

D. Devedzhiev

Part Number: CC1312R

I am working on a proprietary FHSS protocol so I need to change Rf frequency frequently (aproximatly every 20ms) and I have several questions:

1) If I am not goin to change the rf band (lets say that I am working in 868MHz band) does it have to always change frequency settings in both RF_cmdPropRadioDivSetup (rf setup) and RF_cmdFs, or in case that not changing rf band the change with RF_cmdFs is enought?

2) Are there any "rules" how big could be the difference betwee both frequences set with DivSetup and cmdFs?

3) Is there a faster approach to change rf setup parameters runtime than "change Setup"->RF_control->RF_yield? I mean is there a way to avoid losing time for RF_yield (real rf core power-off).

Regards

Dimitar

over 4 years ago

0 TER over 4 years ago

TI__Guru**** 317180 points

In the equation below, F_RF is the frequency set by CMD_FS and centerfrequency is CMD_PROP_DIV_SETUP.centerFreq:

if (F_RF - centerfrequency)/ centerfrequency is less than around 1.5 % you only need to do a CMD_FS to set a new frequency.

0 D. Devedzhiev over 4 years ago in reply to TER

Intellectual 705 points

Hi TER,

Thank you for the answer.

Just to be shure that I understand you correctly - according to your answer I can change the frequency only with CMD_FS as far as it stays within this interval -1.5% centerfrequency < F_RF < 1.5% centerfrequency, am I correct?

Best regards

Dimitar

0 TER over 4 years ago in reply to D. Devedzhiev

TI__Guru**** 317180 points

Just use the equation I posted, meaning:

(F_RF - centerfrequency)/ centerfrequency < 1.5 %.

0 D. Devedzhiev over 4 years ago in reply to TER

Intellectual 705 points

Hi TER,

Let me ask you in other way:

I your equation do you mean that the value (F_RF - centerfrequency) should be considered as an absolute/modulus value (the F_RF could be bigger or smaller then centerfrequency)?

Regards,

Dimitar

0 TER over 4 years ago in reply to D. Devedzhiev

TI__Guru**** 317180 points

Sorry, I was a bit imprecise in a mathematically sense:

It should be abs((F_RF - centerfrequency)/ centerfrequency) < 1.5 %.

Meaning that R_RF could be x Hz lower or higher than the center frequency.

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CC1312R: Frequency change related questions