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CC110L: No sync word detection

Pedro Carneiro da Silva
Prodigy 10 points
Part Number: CC110L


I'm having trouble to detect the sync word (0x1234) with CC110L. My application is 434MHz of center freq. 20kHz of deviation, 162kHz of Rx filter BW, 2.4k baud rate, fixed packet lenght of 8 bytes, 200kHz of channel spacing and using channel 0. This last channel config is the SmartRf recommendation. I'm also using iocfg2 = 0x0e to know when the sync word is detected.

When i use any 16 bit sync word configuration it detects sync word randomly but when i read RX FIFO it is only garbage bytes. In any 32 bit configuration it doesn't detect anything and with preamble/sync word disable it gets my signal but with bit dessynched, which makes sense.

I used the another pin to detect carrier wave and it works as expected.

As can be notted i have tried many different configurations, different sync words, filter BW, deviation, baud rate... But nothing helped the sync word detection. What else could i try? Is any configuration I'm missing?

  • 0
    TI__Intellectual 2262 points

    Hi Pedro,

    Is this happening only for the 0x1234 sync word of for any configuration?

    Have you tried testing it with SmartRF studio?

    Best regards,

    Daniel

  • 0 in reply to Daniel Guarecuco Aguiar
    Prodigy 10 points

    I've tried 0xbcbc, 0xbbbb and the default 0xd391 too. 

    I'm using SmartRf studio to generate register values, the board isn't direct connected to it because is the final board not a development one.

    Best regards,

    Pedro.

  • 0 in reply to Pedro Carneiro da Silva
    TI__Expert 5010 points

    Hi Pedro,

    Which PHY did you use generate your custom settings?

    I have done the following in smartRF studio with based on your settings and I can transmit and receive packets between 2 devices.

    As a starting point I used the 38.4 kBaud 20kHz deviation PHY

    The sync word in SYNC1 and SYNC0 is set to 0xD391 and in MDMCFG2.SYNC_MODE is set to 0x03 making the sync word effectively 0xD391D391.

    I suggest you use the default SYNC word used in studio unless you are trying to communicate with another device that is using a different sync word.

    A few questions to help you debug further:

    Have you checked with a spectrum analyzer that the Tx device is transmitting on the correct frequency?

    Have you tried transmitting from your device to a EM connected to Studio?

    Have you tried transmitting from an EM connected to Studio to your Rx device?

  • 0 in reply to Diego P
    Prodigy 10 points

    I was using this one to generate my custom settings.

    Also tried with yours settings but didn't detect sync even thought it shows that carrier is above threshold.

    Doing some test i noticed that when it comes from power down and i configure GDO2 to output PLL lock with 0x0A value it goes high immediately and a few us after it goes low and even when i strobe SCAL it keeps low forever. What is expected to see when i use 0x0A in the GDoxCFG and strobe SCAL? Could it all be a problem with the oscillator?

    I used the spectrum analyzer to verify the transmitted signal and its fine.

    I do not have and EM or EB to connect with Studio.

    Best Regards,

    Pedro.

  • 0 in reply to Pedro Carneiro da Silva
    TI__Mastermind 18645 points

    Hi Pedro,

    We would strongly recommend intially testing with SmartRF Studio 7 for this.

    For a lower-cost option (than a TrxEB board) you can use a CC Debugger: https://www.ti.com/tool/CC-DEBUGGER

    Section 6.3 of SWRU197 (CC Debugger User's Guide): https://www.ti.com/lit/swru197 details how to connect the CC110L device.

    Regards,

    Zack

  • 0 in reply to ZC
    Prodigy 10 points

    Hi Zack,

    Thanks for the recommendation.

    What about the PLL lock signal? What should be the signal behavior?

    Regards,

    Pedro.