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LMX2592EVM: LMX2592 Burst mode Problem

Kevin Lin
Prodigy 20 points
Part Number: LMX2592EVM
Other Parts Discussed in Thread: LMX2592, USB2ANY

Tool/software:

Hi TI support,

I'm trying to automate a short output frequency sweep by changing Register R45 value (& keeping R44 unchanged)

WriteRawData(0x2C0000);~time.sleep(1);~WriteRawData(0x2D0001);~time.sleep(1);~WriteRawData(0x2C0000);~time.sleep(1);~WriteRawData(0x2D0010);~time.sleep(1);~WriteRawData(0x2C0000);~time.sleep(1);~WriteRawData(0x2D0011)~time.sleep(1);~WriteRawData(0x2C0000);~time.sleep(1);~WriteRawData(0x2D0100);~SetPins("CE","True");

Unfortunately I can't get this to work. First timer of using this part, any suggestions (an example how to code for Burst mode perhaps) will be appreciated.

Thanks and best regards,

  • 0
    TI__Guru* 97600 points

    Hi Kevin,

    Was it locked before you use burst mode to sweep the frequency?

    Could you provide the TICS Pro configuration?

  • 0 in reply to Noel Fung
    Prodigy 20 points

    Hi Noel,

    Thanks for the prompt reply, here're the screenshots and configuration: 

    Please let me know if there are other information I can provide to help assist this case.

    Thanks and best regards,

    Kevin 

  • 0 in reply to Kevin Lin
    TI__Guru* 97600 points

    Hi Kevin,

    You should keep FCAL_EN = 1 all the time. 

    During initial programming (first programming after Vcc power up), load all the registers to make it lock to, in this case, 3600MHz.

    Now you can use Burst Mode to sweep the frequency. 

    You were changing the PLL_NUM, from 0 to 11, this will change the VCO frequency by 6.8MHz. Your script should work. However, if you are sweeping a larger frequency step, you need to program R0 after R45. This is because a VCO calibration is required if the VCO frequency change is big (approx. 10MHz+). Since R44 is not changing, we do not need it in the script.

  • 0 in reply to Noel Fung
    Prodigy 20 points

    Hi Noel, after locking the frequency and load the registers - the issue I'm seeing now is that it only run the very first command but not the rest. Can you help provide an working example?

    Thanks and best regards,

    Kevin

  • 0 in reply to Kevin Lin
    TI__Guru* 97600 points

    Hi Kevin,

    Looks like there is issues with the current version TICS Pro. Please try below the older version.

    snac072au.zip

  • 0 in reply to Noel Fung
    Prodigy 20 points

    Hi Noel, 

    I re-installed TICS Pro with you revision you provided. Unfortunately the device became un-responsive, it seemed that the communication between the device and TICS Pro has been lost. I had to install the latest TICS pro back then I was able to observe the output signal at 1800MHz again.

    Can you help double check if TICS Pro revision you provided is indeed compatible with LMX2592?

    Best regards,

  • 0 in reply to Kevin Lin
    TI__Guru* 97600 points

    Hi Kevin,

    After installing the old version TICS Pro, you need to update the USB2ANY firmware, did you get prompt to update the firmware?

    Try again with the following sequence.

    1. unplug USB2ANY

    2. open TICS Pro (old version)

    3. plug in USB2ANY, TICS will ask you to update the firmware

    4. follow the onscreen instruction to update firmware 

  • 0 in reply to Noel Fung
    Prodigy 20 points

    HI Noel, it works now after updating the USB2ANY. Thanks much for helping Slight smile