I've been playing with FPGA(Cyclone II EP2C5T144C8) with Quartus II 13.0 WebEdition 64bit and Altera USB Blaster.
At first, I was using JTAG mode for programming FPGA into RAM. When I wanted to program EEPROM(EPCS4), so I switched to AS mode.
Since I programmed in AS mode, I can't use JTAG mode anymore. 'Auto Detect' fuction in Programmer window responds with 'unable to scan device chain... bla bla'.
>jtagconfig -d 1) USB-Blaster [USB-0] Unable to read device chain (JTAG chain broken) Captured DR after reset = () Captured IR after reset = () Captured Bypass after reset = () Captured Bypass chain = ()
However, programming in AS mode works. Seems like JTAG mode has been disabled somehow..?