I am working with some NetFPGA-SUME boards and I have an issue that is bothering me. This board contains a Xilinx Virtex-7 690T FPGA, a part that loads a configuration file into internal configuration RAM.
When the FPGA loads the configuration file, the FPGA works all right, but when I leave the board turned on for a while (let's say, a whole night) and use the board, the FPGA seems to lose its configuration and I have to reload the configuration file and restart the computer.
Example: I program the FPGA with a NIC design, I
ping other machine and it sends the message. But when I come back the following day and I
ping the same machine, it is not send by the NIC.
I don't know if it is a normal behavior of an FPGA. Is it possible that I forgot to configure something on the board? I don't thing the FPGA is defective, as I tested it on other NetFPGA-SUME boards and found the same problem.
Has anybody any insight in what could be happening?
Edit: as some people talked about it in the comments and answers, I have also tried to load the bitfile from one of the flash files the board has. The result is the same, and I have to turn off the system so the bitfile is loaded again from flash.
Edit 2: due to one of the comments, I add this piece of information. I have tested the boards with two different power supplies and hosts, with the same exact result.