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CC1200 EMK Modul Problem

Andreas Riesner
Prodigy 180 points

Other Parts Discussed in Thread: CC1200EMK-868-930, CC1200, CC1120

Hi Guys,

i build my own Hardware for CC1200 with the Antenna from DN024. As MCU i use a FR5969. For testing i port the cc120x_easy_link porgramm with orginal register settings. But it will not communicate with the TI CC1200EMK-868-930 Board.

So i tried the direct communication between the EMK Boards. We have at least 12 EMK Moduls and i notice some disappointing behavior.

I tried every modul as RX and as TX part with all the other moduls. Also used a FR5969 (TS430RGZ48C) and the SOC_BB to mount the EMKs.
Green = the Paket received successfully.
Red = the Paket is corrupted or nothing was received.

For my own designs i have some Sample IC (TI 37I AQJ2 G4) and 300x from Mouser (TI 48I AE1Y G4).
So before i got more frustrated by searching the design flaw in my layout... is it even possible to communicate with one of the EMK Moduls?

Thanks for your help!

Andreas

  • 0
    TI__Mastermind 39860 points
    Check if there is a significant frequency offset between units which cannot communicate. Use a spectrum analyzer to measure the frequency offset and account for this when configuring the CC1120. If you do not have a spectrum analyzer one test would be to increase the RX filter BW and/or enable FB2PLL (see user guide, set FREQOFF_CFG = 0x30).
  • 0 in reply to Sverre
    Prodigy 180 points

    Hello Sverre,

    thanks for the hint! I organized a spectrum analyzer and the output frequency has a offset from approximately +70kHz. I increased the RX filter BW from 10 to 200 kHz. Nevertheless, many packets failed at CRC check. I adjusted the Carrier frequency (-70kHz) so it matched the 868 better, this seems to be the best soulution.

    Is the offset just dependent on the crystal inaccuracy and the RCL stuff?
    What does the NO xxxx PbF on the EMK stands for?
    Is there a better way to calibrate the RF Part on all PCB or is the usual way the bigger RX filter BW?

    Big Thanks
    Andreas

  • 0 in reply to Andreas Riesner
    TI__Guru**** 317180 points
    70 kHz offset is a lot.

    The frequency is given by the FREQ register and the xtal. Do you use the same xtal and xtal load caps as the reference design?
  • 0 in reply to TER
    Prodigy 180 points

    Hi TER, thanks for the fast reply.

    Own HW:

     NX3225SA (644-1057-1-ND  @digi) with 8pF

    EMK HW:

     NX3225SA EXS00A‐CS03880 with 15pF

    The 70kHz was with the EMK (EMK10)  and my Crystal+pF.  Attached my Meassurements:

    EMK 1:

    EMK 3:

    EMK 10:

    EMK 11:

  • 0 in reply to Andreas Riesner
    TI__Guru**** 317180 points
    Note that it is the total load that should be 8 pF. If you have used 2 caps equals to 8 pF the load will be much too low. This correspond with too high frequency
  • 0 in reply to TER
    Prodigy 180 points
    Thanks a lot TER. Learning never stops.