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Original question:

RTOS/CC1310: Changing Frequency On-the-Fly w?EasyLink API

RTOS/CC1310: RF_yield in EasyLink_setFrequency

Hans Christian Glittenberg
Expert 2235 points
Part Number: CC1310

Tool/software: TI-RTOS

Hi,

Related to https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz/f/156/t/705756

Why is RF_yield(rfHandle); placed after RF_control?

According to the API, RF_yield is a notification to the RF core that no new further commands will be issued for a while and thus the radio can be powered down at the earliest convenience.

However, RF_runCmd is to be run immediately as the next command. The task of changing frequency is also a lot slower with RF_yield.

Is this command needed for some reason?

  • 0
    TI__Guru* 86101 points

    In the case you are reffering to, the change of the frequency also requires a change of the setup command. The RF_control function is used to update the setup command (RF_CTRL_UPDATE_SETUP_CMD). However, the updated setup command will not take effect before the next power up cycle when RF executes the setup command. The RF_yield is called to force the radio to power down and hence waking up using the new setup.

    Siri

     

  • 0 in reply to Siri
    Expert 2235 points

    Hei Siri,

    Thanks for the clarification. In my setup I use LRM 5 kbps. I measure 1.62 ms between end of TX to new TX when changing frequency in-between (I use the RAT_GPO0). I also notice the calibration occurring within this 1.62 ms delay, which is 0.22 ms.

    Is there any way to speed up the latency between each TX when changing frequency (a quicker power cycle perhaps)?

    I am also not sure if the "modified" setFrequency is needed for my application which is from 902 to 928 MHz (915 ISM band).

  • 0 in reply to Hans Christian Glittenberg
    TI__Guru* 86101 points
    Hi

    Unfortunately, there are no ways to speed up this, if you need to do the setup command.

    The centerFreq in the setup command is used for two things:

    1) It scales the deviation in TX
    2) It scales the RXIF

    If you set the centerFreq @ 915 MHz, you change the RF frequency +/- 1.5% and hence the deviation and RXIF will vary 1.5%.

    When it comes to the deviation, this should not be a problem.
    Regarding the RXIF, it depend on the required frequency offset tolerance.

    If the RXIF is 250 kHz, you will end up with a frequency error of +- 3750, which means +/- 4ppm on the RF.

    BR
    Siri