Altera JTAG Problem

Hello ~

We are using the 3 stratix4 as 1 chain, but it is separated from JTAG for flash rom.
In other words, JTAG signals are shared for 3FPGAs.

Program for EPC device is okay, but problem is about JTAG connection for FPGA.
Almost case USB blaster can't find JTAG chain when I push the autodect button.
(Sometimes they can initialize successfully.)
And at JTAG debugging windows, if push "Test JTAG Chain",
then programmer could find the FPGAs successfully
but it generate the 3 lines error message as below.(See attached captured error.)
- Error : JTAG chain problem detected
- Error : The TDI connection to the first detected device EP4SE530 might be shorted to VCC or is an open circuit
- Error : The TCK and TMS connections to the device before the first detected device EP4SE530 might have a problem

So I have tested many cases.
- When I take a Probing some signal, TDI, TDO, TCK looks as good.
- When I use byteblaster, also same error is displayed.
- Re soldering at some points, changed OS, reinstall altera programmer or driver ... ==> same error

I wonder the about my case...
- They can find device, it means some communication are succeeded, correct ?
- Then which condition can cause the error message like that? What is the Error criteria ?
- What is the next test step after finding the device ?
=> I wonder the software's action when I push the "Test JTAG Chain" button.

And my circuit is as below,
- Pull-up for TDI, TMS is 2.5k ohm.
- Pull-down for TCK is 1k ohm.
- JTAG Pin 6 is not connected.
- Vcc for JTAG is 2.5V
- Program mode for EEPROM is AS Mode and JTAG for program is separated from JTAG for FPGA I/O.

Could you help me for my issue ?

Regards,
JS Lee

Attached Images

• error capture.jpg (95.5 KB)