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 gives:

>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..?


1 Answer 1


I had the same or very similar problem ("JTAG chain broken"). It seems to solve the problem if I download libudev1:i386 and create a symbolic link

$ sudo apt-get install libudev1:i386
$ sudo ln -sf /lib/x86_64-linux-gnu/libudev.so.1 /lib/x86_64-linux-gnu/libudev.so.0

Now it works:

$ jtagconfig
  1) USB-Blaster [2-4]
  020F70DD   EP3C120/EP4CE115

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