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Altera_Forum's avatar
Altera_Forum
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12 years ago

JTAG design for cyclone iii ep3c5E144

Dear all,

This is my first attempt to create a FPGA board. My board only uses JTAG (no AS) for programming. I have attached the schematic and board in the *.zip file. Would you please having a look for me?

I have some doubts

1/ Should I connect nCE of JTAG directly in to nCE of the FPGA, or nCE from FPGA is connected to ground?

2/ About the clock: I see that there are 16 clocks. To which clock I should connect the output from oscillator to?

3/ In my board, I only use 3.3V (the label VCC means 3.3V). Is that ok?

Thank you for your help,

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    By the way, would you please showing me how to add a flashing LED to indicate the JTAG is working?

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    nCE function is related to the AS/AP configuration interface. It's purpose is to tristate the FPGA signals driving a configuraton memory. It can be tied to GND if no external access to a configuration memory (through AS programming connector or embedded processor) is intended.

    Your design is missing 1.2V and 2.5V supplies. Both are required by the Cyclone 3 FPGA, read the device manual. Furthermore bypass capacitors at all power supply pins are strongly suggested.

    I would always add a serial configuration flash (EPCS or compatible) to the design. It can be programmed through JTAG indirect method.

    A single clock input is sufficient for most basic designs.
  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    --- Quote Start ---

    nCE function is related to the AS/AP configuration interface. It's purpose is to tristate the FPGA signals driving a configuraton memory. It can be tied to GND if no external access to a configuration memory (through AS programming connector or embedded processor) is intended.

    Your design is missing 1.2V and 2.5V supplies. Both are required by the Cyclone 3 FPGA, read the device manual. Furthermore bypass capacitors at all power supply pins are strongly suggested.

    I would always add a serial configuration flash (EPCS or compatible) to the design. It can be programmed through JTAG indirect method.

    A single clock input is sufficient for most basic designs.

    --- Quote End ---

    Hi, thank you for your prompt response. I also just realized that I missed 1.2V and 2.5V. But the symbol confused me. I thought that all of the VCC pin of the symbol should be connected to 1.2V. Can you please show me which pins are 1.2V, which are 2.5 V according to the symbol?

    Also, is it ok if I only use JTAG without AS?

    Thanks