i am using the cyclone iii ep3c120 development kit. i can successfully program my .sof into the fpga directly via the usb blaster interface.
i followed the instructions in the development kit user guide (appendix a) to create a .pof file, and then to program the flash. at step 9 - "click auto detect" - no flash device is detected.
i should note that the very first time i tried to implement the design into flash, everything worked perfectly. now that i have updated the design, it does not.
can anyone suggest why this is the case?
The user guide doesn't talk about programming your file, but the supplied example design. If your design doesn't include a PFL instance, no flash can be auto-detected. You are still able to attach the flash manually, but you need a PFL instance in the FPGA design to perform the flash programming.
As far as I recall, one of the pre-programed(factory default) design in Flash does have PFL in it. I thought it was page 1 or 2...Or as Fvm mentioned, easiest way is just build PFL only design by yourself. Just instantiate PFL from Megacore, and hook up Flash pins to PFL.