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Altera_Forum
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10 years ago

Cyclone IV configuration - nCONFIG signal and JTAG programming issue

Hi, I have a custom board for EP4CE22E22 Cyclone IV FPGA. I have configured the board for JTAG only mode and using USB Blaster Rev.B for programming. The problem I am facing is that JTAG Scan f...
Altera_Forum's avatar
Altera_Forum
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10 years ago

No it can't be a license problem. If you had some Opencores IP it would only work when uploading the .sof file using the programmer and you wouldn't be allowed to flash the design into the EPCS.

I would rather look for some earthing/grounding problems. When you connect the USB blaster to your board and the PC, you connect your board's ground plane to earth.

Another possibility is load on the JTAG pins or the VCC power plane connected to the JTAG connector. Do you have pull-up/pulldown resistors on the FPGA's JTAG pins? It's not required but depending on your PCB design they could pick up noise during startup that would disturb the start-up process.