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CC110L: Frequency Hopping

Part Number: CC110L

Hi everyone,

I am using 430BOOST-CC110L RF BoosterPack and I found in the datasheet that CC110L supports frequency hopping. I want to send some frames to an RF receiver in three channel: 433.589MHz, 433.920MHz and 434.251MHz.

In the datasheet §5.27.2, it is mentioned that a calibration process is required when implementing frequency hopping, it affects three registers: FSCAL1, FSCAL2 and FSCAL3. Moreover, it is mentioned that, between each frequency hop, this calibration process can be replaced by writing the FSCAL3, FSCAL2 and FSCAL1 register values that corresponds to the next RF frequency.

By using SmartRF studio to configure my transceiver I have noticed that for those three channels(433.589MHz, 434.251MHz, etc.) FSCAL registers retain the same values. that being said, when implementing frequency hopping all I should to do is setting the new values of FREQ0, FREQ1 and FREQ2 registers (the only registers that change when I switch between the freq channels ) ?

Should I configure the transceiver registers everytime I enter IDLE state or their values are preserved and the only registers I have to configure are the ones that I want to change(FSCAL registers in this case)?

It is mandatory to enter IDLE state to configure the transceiver registers?

To apply frequency hopping, what is the difference between using channel number with channel spacing and directly configuring FREQ registers?

I will be very grateful if anyone could help me to figure out how to implement frequency hopping.

Best regards,

Mohamed

  • Hi Mohamed

    Even if the FSCAL registers have the same value when writing them for 3 different frequencies, they might be different after performing the calibration (the registers holds the calibration result).
    That means that for fast frequency hopping you should write to the FREQ and FSCAL registers for freq. 1, perform a calibration and then read back the FSCAL registers and store them. Repeat for freq. 2, and freq. 3.
    After you have the calibration result for the 3 frequencies you want to use, you need to write these registers (and the corresponding FREQ registers) when changing frequencies.
    The radio must be in IDLE state when writing to these registers.
    The advantage of using the CHANNR register is that you can have 1 register access instead of 3.

    BR
    Siri
  • Hi Siri,

    Thank you for your continuous support.

    In my application, I am using automatic calibration when going from IDLE to RX or TX, or back to IDLE (FS_AUTOCAL = 01) I don't use SCAL strobe to calibrate the frequency synthesizer. In this case, should I change FSCAL registers even though automatic calibration is enabled or all I need to do is to change FREQ registers?

    Best regards,
    Mohamed
  • If you are using FS_AUTOCAL = 01, you only need to write to the FREQ register (or CHANNR) given that SmartRF Studio gives the same value for the FSCAL registers for all the different frequencies you are using.
    You should not use FS_AUTOCAL = 10 or 11 when operating on several frequencies (You mentioned calibrating when going back to IDLE).

    BR
    Siri
  • Thank you so much Siri, that's exactly what I was looking for.