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CC1310: Cannot adjust the frequency with step = 15Hz

user5173365
Prodigy 140 points
Part Number: CC1310

Hi, 

We set up for RF: Frequency 922MHz, Baudrate 100kbps.

There are 2 variables related to setting frequency:
① RF_cmdFs.frequency (16bits)
② RF_cmdFs.fractFreq (16bits) (theoretically, Step = 1000000/65536 = ~ 15.3Hz)

When the actual test, we can only change the frequency with step = ~ 750Hz, when increasing or decreasing RF_cmdFs.fractFreq about 51.

We want to confirm really can only adjust the frequency of about 750Hz or because we did not set up correctly? Are there any documents related to this issuse?

  • 0
    TI__Guru**** 317180 points

    The actual synth resolution is about 750 Hz (the actual number will vary some with the RF frequency) meaning that your observation is correct. 

    The synth resolution is given as:

    (FREF/2^11)/(LODIV/2)

    Where FREF is 4 MHz and lodiv can be found from SmartRF Studio for the band you are operating in.

    The easiest would be to let SmartRF Studio calculate the .fracFreq.