I mistakenly used an EPCS16 (8-pin SOIC) in my design with a Cyclone III EP3C120. Active serial has been working but if I use more than half the chip then my program will probably not fit in 16Mb anymore. I ordered an EPCQ32 (same 8-pin SOIC package) and put it on the board and I can program the EPCQ32 but the FPGA does not load. I tried programming directly via the USB Blaster and active serial header as well as through the FPGA using JTAG. The chip programmed successfully both ways but when I examine the EPCQ32 I sometimes get a bad CRC. I tried removing the USB Blaster and cycling power with no luck. I probed the pins with a scope and it appears to be trying to load so I left it for a couple hours and when I came back it had loaded. I tried removing the active serial protection diodes and caps but that did not work either. Should an EPCQ32 work with an EP3C120 or am I doing something fundamentally wrong?
I think I figured it out, I can use the EPCQ32 but I have to select "Disable EPCS ID Check" under advanced when converting the programming file. I don't know why that was not the default for my selections but that's ok, life is good...
"Disable EPCS ID Check" is only for configuration purpose.Cyclone II and other older devices (prior to V series) cant recognized EPCQ device ID when this EPCQ is sending data to the FPGA.Thats why disabling the option solved the issue. If used with <EPCS128, there is no need to disable it. Note that Cyclone II was developed long time ago before the EPCQs.
you could check steps you generate JIC file for EPCQ32. JIC file generated for EPCS16 and JIC file generated for EPCQ32 are not the same. when you program EPCQ32 failed, what error information in QII? and I didn't saw Cyclone III can support EPCQ in its handbook.
