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LMX2572EVM: SPI DO Issue of LMX2572EVM with Zync7030 FPGA Board

Derek Wang
Intellectual 615 points
Part Number: LMX2572EVM
Other Parts Discussed in Thread: USB2ANY, LMX2572

Hi TI Expert, 

Below is what my customer's question about LMX2572EVM.

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These figures below are the waveform we observed using chip scope according the different SCKs, which are 50MHz and 25MHz respectively.

The question is why I change the SCK’s frequency, but the SPI DO’s pulse width doesn’t change according to the SCK’s frequency. SPI DO’s pulse width seems always a constant no matter how I adjust the SCK’s frequency. Is it possible to adjust the spi_do’s width? Or should I commend which register to achieve this purpose we truly want?

  • 0
    TI__Mastermind 27641 points
    Derek,


    Here, it looks like you are trying to write your own programming interface, and asking about the timing of this, which is not really a question about the LMX2572 and we really don't have good support. We do have the TICSPro tool that can help set up what registers to program and to what values, but you cannot change the write speed on this. I see you have the USB2ANY, but I don't know how to adjust the write speed on this or if it can be done.

    If you are talking about reading back from the device, the data is clocked out on the falling edge of the SCK.

    Regards,
    Dean