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Altera_Forum
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8 years ago

Using Cypress FX3 as device for Passive Serial

Hey,

So I'm working on a setup with the Cyclone 3 (specifically EP3C5E144C8N), which uses a Cypress FX3 board as the passive serial initialisation device. Unfortunately I cant seem to get the device to successfully complete initialisation. So Far I have made sure the following things are in working order.

- Bytes are shifted out LSB first from the FX3

- The .rbf file that I export from quatrus is for the correct device and passive serial configuration

- The nConfig and nStatus timings are correct

- The clock for the data stream is 25MHz (less than the 100MHz max)

- The MSEL pins are the necessary configuration (000)

The only thing I can find that is going wrong is that nStatus occasionally drops low during the configuration process.

I have it connected to and oscilloscope so I can upload waveforms and circuit diagrams if necessary.

Kind Regards

7 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    nSTATUS going low before configuration completes indicates the FPGA has detected an error.

    I'm concerned about the relative timing between the clock and data. If you're configuring from such a remote source - by the looks of the FX3 solution it's going to be quite a lot further from the FPGA than ideal - then 25MHz sounds a little punchy to me, regardless of the 133MHz max speed supported by Cyclone III.

    What does the relative timing between DCLK and DATA0 look like at the FPGA?

    Cheers,

    Alex
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    It was in fact a timing issue between DCLK and DATA0. It turns out I missed a setting in the FX3 firmware that changed it to clock the data out on the Positive Edge rather than the Negative Edge.

    Thanks for the quick reply's.
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    Hi,

    RickyThomson, I would like to know if the passive serial configuration by Cypress FX3 has worked successfully. I could do this passive serial using xmega microcontroller and I may need this FX3 setup later.

    Thanks
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    Hi RickyThomson,

    Thank you for your reply.

    I believe you used some GPIOs from the FX3 chips as control input and output to handle nStatus and nConfig. I think you also used some pins as SPI to handle the DCLK and DATA, right??
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    Yeah that's correct, you set it all up in the FX3 firmware and the GPIF II.