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Altera_Forum
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17 years ago

Combining AS and JTAG configuration schemes

Hi all ! I am a newbie in FPGA field. I am trying to design very simple Cyclone III FPGA board as follows * FPGA : EP3C10E144C7 * VCCIN : 1.2V * VCCD_PLL1,2 : 1.2V * VCCA : 2.5V * VC...
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Altera_Forum
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17 years ago

I'm having the identical problem with my EP3C5E144C8 device. I have another design which uses the EP3C5U256C8 and have no problems with it. The schematics are identical in the two cases except, of course, for the device pinouts.

One thing I notice is that although the JTAG pins TMS and TDI are pulled up to +3.3V through 10K resistors, they only pull up to about 0.8V (with no cable attached). Also, nConfig is pulled up to +3.3V through a 4.99K resistor, but only pulls up to about 1.1V. Something is clearly wrong. I've gone over the device pinout multiple times but can find no errors.