Scan Chain Fails After FPGA is Programmed Once

[nimapf]

Hi,

I have an Actel Igloo FPGA on a custom FPGA board for controlling a few components over SPI interface. I have managed to program the FPGA despite an initial errors including a "TDO stuck at 0" fault. That fault turned out to be due to faulty soldering. However, I am now getting a scan chain failure after I successfully programmed the FPGA once. I program the chip and the FlashPro interface gives me a successful termination message; I test the board; I make a change in the code and program with the new data, then I get a scan chain failure error.

Could something in the code already loaded into the chip keep the JTAG from working properly? Or is it that something in the code have damaged the chip? I would appreciate any ideas as to what could be happening here.

Thanks,

 

[shaiko]

Could something in the code already loaded into the chip keep the JTAG from working properly?

NO

Or is it that something in the code have damaged the chip?

Possibly.
Please post your schematics.