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Original question:

LMX2571: LMX2571

LMX2571: LMX2571

ATHIRA K VINOD
Prodigy 90 points

Part Number: LMX2571

Tool/software:

Dear Team,

I would like to know the following details for the SPI interface in microwire of LMX2571.

  1. clock frequency
  2. clock polarity
  3. clock phase

Thanks & Regards,

Athira K

  • 0
    TI__Guru** 120050 points

    Hi Athira,

    The device supports mode 0 and mode 3.

    SPI speed is available in the datasheet.

  • 0 in reply to Noel Fung
    Prodigy 90 points

    Dear Noel,

    from the above image it shows like Tcwh and Tcwl are 5ns. 

    SPI CLOCK FREQUENCY = 1 / Tcwh+ Tcwl

     

    SPI CLOCK FREQUENCY = 1 / 5ns + 5ns

     

     SPI CLOCK FREQUENCY = 100Mhz. can u please confirm is this clock frequency Right. Because 100Mhz is very huge frequency so we want to confirm this.? Also can we reduce this frequency?

    Thanks & Regards

    Athira K

  • 0 in reply to ATHIRA K VINOD
    TI__Guru** 120050 points

    Hi Athira,

    Right, max. is 100MHz.

    As long as SPI clock is not higher than 100MHz, it will work. 

  • 0 in reply to Noel Fung
    Prodigy 90 points

    Dear Noel,

    Thanks for the reply.

    We are trying to program the LMX2571EVM from an STM processor through the microwire, instead of the TICS pro software. We are not getting the output. seems like code is not loading into the IC. Can you help out?

  • 0 in reply to ATHIRA K VINOD
    TI__Guru** 120050 points

    Hi Athira,

    We don't support SW development. 

    In this case, make sure your SW loads exactly the same register values to the device. 

    You can test your SW by just programming POWERDOWN = 1, this should power down the device and you should see significant current drop. 

    Use a scope to probe the SPI signals, ensure they meet datasheet requirement.

  • 0 in reply to Noel Fung
    Prodigy 90 points

    Dear Noel,

    I followed up your instructions. Below are the updates.

    1. The EVM has been powered down (using power down bit)  through MCU with the algorithm we made.

    2. After power down, we were able to power it up also.

    3. We were also able to reset the registers, by writing the R0 register

    4. We used MUXOUT pin, were able to readout the registers using MCU and see the register values on our screen.

    All this worked fine. But we try to change frequency, it is not working. That is writing to registers other than R0 is not reflecting in the register. We would like to seek your assistance. Any idea why this issue arise?

    Regards,

    Athira K

  • 0 in reply to ATHIRA K VINOD
    TI__Guru** 120050 points

    Hi Athira,

    Do you have an example configuration? For example, below configuration has 480MHz signal coming out from RX port.

    After Vcc power up, program all the registers from R60 to R0.