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I am designing the JTAG for a Altera Cyclone 3 (EP3C5E144C8N). I was only aiming at normal JTAG, and do not need Active Serial. I have attached the schematic and board in the *.zip file (http://www.mediafire.com/?0gt55eyperbm385)

Or just a snapshot here:

enter image description here

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 (clk0 t clk15). 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?
  4. By the way, would you please showing me how to add a flashing LED to indicate the JTAG is working?
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    \$\begingroup\$ I've done a board for Cyclone IV, which should be fairly similar, have a look in here: bitbucket.org/avakar/omicron_analyzer/src/… \$\endgroup\$ – avakar May 12 '13 at 8:09
  • \$\begingroup\$ Hi there, thank you for generousity. Just one more doubt, is that ok if I use 3.3V for the entire board? Just like this board ebay.com/itm/… They provide the schematics here, which seems to use only 3.3V etang.co.uk/datasheet/FPGA/EP2C5T144mini.pdf \$\endgroup\$ – Josh Vo May 12 '13 at 9:05
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    \$\begingroup\$ They're also using 1.2V (the stabilizer is at C8), they're supplying it to VCCINT (at D1). They're also supplying it to VCCA, which is wrong, VCCA should be connected to 2.5V (and according to the datasheet should be connected even if PLL is not used). \$\endgroup\$ – avakar May 12 '13 at 9:10
  • \$\begingroup\$ Sorry for the amateurish questions. I am using the library provided by Eagle itself for Cyclone 3. Im sure you also have it in Eagle (or I have uploaded it here: mediafire.com/?5jrc6tn33gw24w3) This symbol is so confusing for me. I have no ideas where is VCC, VCCINT, VCCA. Would you plz tell me how to get it correct? \$\endgroup\$ – Josh Vo May 12 '13 at 9:23
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    \$\begingroup\$ The device may consist of multiple symbols, some of which are not automatically added to the schematic. Use the INVOKE command on the FPGA, you'll see all the symbols and will be able to add them to the schematic. \$\endgroup\$ – avakar May 12 '13 at 11:20
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Should I connect nCE of JTAG directly in to nCE of the FPGA, or nCE from FPGA is connected to ground?

I'm not sure what you mean by "nCE" of "JTAG", but the nCE pin of the FPGA should be tied low. It is only used in multi-device configuration scenarios, where you daisy chain devices by connecting nCEO of one device to nCE of the next.

About the clock: I see that there are 16 clocks (clk0 t clk15). To which clock I should connect the output from oscillator to?

It doesn't matter, choose whichever is easier for you to route.

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

I doubt it. Doesn't the device require 1.2V for core logic and 2.5V for PLL?

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

You can just connect a LED via resistor between 3.3V and TMS. The pin is driven by the programmer and will be low most of the time during the programming.

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