an error occurs during configuration（nSTATUS)

[Altera_Forum]

Hello all， 

Please help! We have a problem with cyclone III during configuration。My fpga used in AS and JTAG modes ,all the configuration pins are connected to the GND or VCC through resistors or directly according to a previous available fpga project 。But I can't program it in any modes. The nSTATUS pin is pulled low for 60us,and then pulled high for 1us. It is pulled in cycles. I have check the circuit and voltage,but nothing. What can I do for this problem?:( Appresuated for any help.  in addition:my fpga is EP3C25E144I7.In the bottom of the EP3C25E144I7,there is a single GND pin which may be not connected very well. Shall it influence?

[Altera_Forum]

These problem has been solved,thanks~! 

1、I don't try to program it in JTAG mode again for a period of time.Because I think the nSTATUS signal is not right. But to my surprise ,when I try program again ,it can be programed in JTAG mode now! Befor programed in JTAGmode, the nSTATUS is pulled low and high in cycles.After I program it in JTAG mode ,nSTATUS is pulled high steady. 2.Although , the AS mode still can't used at all. As the JTAG mode is right, I doubt the problem is occurs by EPCS16 . Erenow, I had replaced the EPCS16 by new ones for three times! Now, I decide replace the EPCS16 by a old one which had been used in other board. It can be work!!! Are the new EPCS16 I bought bad ???

[Altera_Forum]

It could be a bad batch yes. Are you sure they are genuine EPCS chips that can be traced back to the manufacturer? 

About your second question, you should ensure that the bottom pad is correctly connected to ground. You will have configuration (and run-time) problems if it isn't well connected.

[Altera_Forum]

Thank you for your reply！I quite agree with you！