Debugging JTAG for cyclone III

Altera_Forum · ‎06-06-2013

Hi,

I have just finished my very first FPGA board, with an EP3C5E144C8N programmed by JTAG (no AS). I have attached the design in *zip.files (actually it is the old circuit, I changed thing a bit but the JTAG is the same), or the image can be found here: http://i.stack.imgur.com/2calk.png

When I used the programmer in Quartus to test JTAG, at first I received the error "no device detected". I check the voltage of the pins as followed (when there are no program loading):

TMS: GND

TDO: 2.1V

TMS: 3.3V

TDI: 3.3V

After a while, I re-loaded the program and received the error stated that JTAG Chain is in used ( and also it took very long to give a "Failed" warning)

My board has a 3.6MHz clock, and core logic of the FPGA is at 1.2V. For the the 144EQFP package, I have tried to solder the pad below the FPGA.

Would you please telling me what could happen in my case, and how can I debug the JTAG? Some told me that even when there are no clock, with appropriate configuration of JTAG, the program can still load. Is that correct?

Thanks for your help

Altera_Forum · ‎06-06-2013

One thing that's not right according to Cyclone handbook:

--- Quote Start ---

Do not leave the MSEL pins floating.

--- Quote End ---

--- Quote Start ---

I have tried to solder the pad below the FPGA.

--- Quote End ---

That's in fact essential.

Altera_Forum · ‎06-07-2013

Thank you, I realized that I missed MSEL2 (Silly me!). But, is the TDO voltage level correct?