blueseahaichao

这里有个概念错误。FPGA的编程是硬件编程，编程后，FPGA就成为你所设计的硬件，所以不存在什么程序掉不掉的问题。FPGA的程序问题也就是硬件问题， 因为FPGA的编程是硬件编程。有许多原因可能造成你说的情况，其中一个常被疏忽的就是没使用的管脚的定义，不能让它们FLOATING(悬空)。另外，你的程序是最后烧在PROM里而不仅仅是灌在FPGA芯片上吧？

blueseahaichao

For the spartan3 familay, A pin supports differential standards if the pin is labeled in the format “Lxxy_#”. The pin name suffix has the following
significance:
• ‘L’ indicates differential capability.
• "xx" is a two-digit integer, unique for each bank, that
identifies a differential pin-pair.
• ‘y’ is replaced by ‘P’ for the true signal or ‘N’ for the
inverted. These two pins form one differential pin-pair.
• ‘#’ is an integer, 0 through 7, indicating the associated
I/O bank.

If unused, these pins are in a high impedance state.