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cc2538 - The frequency synthesizer failed in Z-Stack

Vanessa Borba
Intellectual 255 points
Other Parts Discussed in Thread: CC2538, Z-STACK

Hello,

We use the z-stack Smart Energy 1.1.0 in cc2538. The company developed the layout of the board for cc2538 in compliance with Texas guidelines. But our board can't to send RF signal. By IAR, in the debug we find that the RFCORE_SFR_RFERRF (0x4008882c) register is with the value 0x0009, signaling NLOCK error -. "The frequency synthesizer failed to Achieve lock after time-out, or lock is lost During reception The receiver must be restarted to clear
this error situation. "

However, the z-stack operates as normal as if you were sending the RF packages. But, hardly the sniffer captures such packets. Of the few captured packets, LQI = 0.

Have any tips what we should do to solve this problem?

  • 0
    TI__Mastermind 27145 points

    Hi,

    I recommend to do the following to find the problem. 

    You can use our SmartRFStudio and test your board in Continuous TX - Unmodulated mode. This shows the Synthesizer Lock status on the RFStudio window and you also may use Spectrum Analyzer to check the frequency accuracy and stability of the transmit signal.

    If the LOC_ STATUS fails in this test then there might be a problem on the board. You need to investigate further.

    For receiver also, you can test it by using Continuous RX mode in SmartRFStudio. You may use RF Signal Generator or CC2538 as a continuous transmitter for RF input signal to the Receiver.

    Thanks,

    PM

  • 0 in reply to PM
    Prodigy 25 points

    Hello PM,

    I'm Vanessa's coworker.

    First of all, thank you for your response.

    Using SmartRFStudio's Device Control Panel, the Continuous TX unmodulated do not turn LOCK_STATUS on. The spectrum analyzer on our board have no effect.

    the Continuous RX test don't show any difference on RSSI graph. CCA and LOCK_STATUS don't turn on

    We've done the same test on CC2538's demo board and it run well.

    We already have another PCB working on with CC2538. The new PCB use the same components and basicly the same layout of the other one.

    Is there another test we can do?

    Thanks alot,
    Eduardo Cury

  • 0 in reply to Eduardo Teixeira
    TI__Mastermind 27145 points

    Hi Eduardo,

    It seems synthesizer is not locking.

    Did you check 32MHz Crystal oscillator? Check the frequency and level and comare with the good board.

    You may also check the power supply voltages on the supply pins?

    How many boards have this problem?

    At the end, you may need to change the chip and check the performance again. Please use ESD precautions in handling the device and the baords.

     

    Thanks,

    PM

     

     

  • 0 in reply to PM
    Prodigy 25 points

    Hi PM,

    The clock frequency is ok, and the 3V3 supply has no flicker or ripple. This problem occurs to all new PCB. We mounted 6 pcbs and the same error occurs to all of them.

    Can this problem be a Layout problem?

    Thanks,

    Eduardo Cury

  • 0 in reply to Eduardo Teixeira
    TI__Mastermind 27145 points

    Hi,

    Yes, I suspect this could be a layout/assembly problem. But to confirm that you may swap the chips from good board to the bad board and see what happens. If the problem still exists with the board that shows that the problem with the layout. If the problem follows the chip then the problem with the chip.

    Thanks,

    PM