Is there data exchange between SPI controller and Visual Analog or HSC-ADC-EVALCZ FPGA?

I am currently working with the AD9637-80EBZ evaluation kit in conjunction with the HSC-ADC-EVALCZ evaluation kit. for the ADC value readout I use the Visual Analog software and the ADC's SPI interface is controlled by the SPI Controller from AD. A 20Mhz clock is supplied to the AD9637-80EBZ evaluation kit and J804 is removed. The binary file inside the Virtex-4 FPGA on the HSC-ADC-EVALCZ evaluation kit is Octal_Low_Speed.bin because sample-rate < 30Msps. When the input formatter in the Visual Analog software is set to 2's complement (Resolution: 12 and Alignment 12) and the ADC is configured to output the data in 2's complement mode everything works fine. If I change the ADC output mode setting (register 0x14) to offset binary mode everything still works fine while the data that is transmitted to the Visual Analog software has a different format (not 2's complement). When I change the input formatter from 2's complement to offset binary things start to get worse even more. What I see on the graph is the binary representation of 2's complement values.

Is there a possibility that the FPGA / Visual analog software knows in which format the incoming data is formatted? Also when the SPI register is changed?

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    •  Analog Employees 
    on Oct 21, 2017 6:50 AM

    Hi Oceley,

    Thank you for working with AD9637. I'm observing something different on my bench.

    AD9637 Output Format Set by SPIController VisualAnalog Input Formatter Setting Result in VisualAnalog (FFT)
    2s Complement 2s Complement FFT looks good
    Offset Binary 2s Complement FFT looks bad
    Offset Binary Offset Binary FFT looks good
    2s Complement Offset Binary FFT looks bad
    2s Complement 2s Complement

    FFT looks good

    One difference is that I was sampling at 80Msps, so I did not use Octal_Low_Speed.bin.

    VisualAnalog gets information from the ADC (e.g. chip ID) to determine which canvas to load. I do not believe that it knows what changes you make to the ADC configuration from SPIController.

    VisualAnalog and SPIController have the ability to communicate with both the ADC and FPGA.

    Is what you observe limiting your ability to evaluate the AD9637?

    Thank you.

    Doug

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  • 0
    •  Analog Employees 
    on Oct 21, 2017 6:50 AM

    Hi Oceley,

    Thank you for working with AD9637. I'm observing something different on my bench.

    AD9637 Output Format Set by SPIController VisualAnalog Input Formatter Setting Result in VisualAnalog (FFT)
    2s Complement 2s Complement FFT looks good
    Offset Binary 2s Complement FFT looks bad
    Offset Binary Offset Binary FFT looks good
    2s Complement Offset Binary FFT looks bad
    2s Complement 2s Complement

    FFT looks good

    One difference is that I was sampling at 80Msps, so I did not use Octal_Low_Speed.bin.

    VisualAnalog gets information from the ADC (e.g. chip ID) to determine which canvas to load. I do not believe that it knows what changes you make to the ADC configuration from SPIController.

    VisualAnalog and SPIController have the ability to communicate with both the ADC and FPGA.

    Is what you observe limiting your ability to evaluate the AD9637?

    Thank you.

    Doug

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