Forum Discussion
Honored ContributorStratix III JTAG Failure
Hi All,
I have problem on Stratix III device on my Custom development board. Device: Stratix III - EP3SL340 Download cable : Altera USB Blaster We have provided two configuration option to configure the FPGA (JTAG & Passive serial). Only one device is connected with the JTAG interface. We are frequently using JTAG & USB blaster interface to validate our designs. so far It was working nicely. Suddenly the quartus Tool is not able to detect the device from the JTAG chain. I just went through the JTAG troble shooter, It gives the information of possible failure in the JTAG interface signal, Also I have noticed that TDI pin is almost shorting to GND. It shows 2 Ohm between TDI to GND. Whereas the other working board it was around 150 to 200 ohm. This is the second board I am facing the same issue. Is it the problem with the Stratix III device JTAG interface. Can anyone help me to findout the root cause for this trouble. Best Regards, Kalidoss22 Replies
Altera_ForumI had exactly the same thing and solved in the same way.
Our JTAG was not working anymore while the board worked for more than a month. TDI was measuring 50 Ohm to ground. We suspected an FPGA problem and no board problem. I disconnected the normal powersupply and I applied 5V to TDI from seperate power supply and ground to the ground of the board. This to "burn" the short in the FPGA... small change that it worked but as I could not use JTAG anyway it was no big loss if the FPGA would burn completely. The resistance was increasing. After applying the voltage for a second it was 70 Ohms, applying again for 5 seconds it became 150 Ohms but still not working. After another 10 seconds it became 2 Ohms and I put the board aside because I thought the board was now completely defective. However, after reading this thread I tried it again. TDI became 5k and I can program the JIC into the board. FPGA was a Stratix III 3SL70F780C4N. How can this happen? Is it a bad FPGA... or could short on TDI caused by electrostatic discharge?- Altera_Forum
Thanks but no hope for me :p
- Altera_Forum
No the board wasn't powered. I applied this voltage on just that jtag pin.
- Altera_Forum
Hi, on you post #17 (http://www.alteraforum.com/forum/showpost.php?p=146228&postcount=17), do you apply 3.8V when your board is powered or not ?
- Altera_Forum
ohming it may not be significant, but it was the problem and it fixed it.
- Altera_Forum
Altera recommands to supply power on the board before plug USB Blaster in.
TDO is an output pin : depends of technology (open-drain, TTL...) ohming it is not significant. JTAG problems seems to grow up last months on Cyclone II, Cyclone III, Stratix III - Altera_Forum
Actually I just fixed a shorted TDO pin to ground by applying 3.8V to it. The pin went from 40 ohm to ground to over 200 ohm and now JTAG works again.
I don't know why it failed, the board has been working fine for weeks. Today JTAG just stopped working. I guess a protection diode blew out and shorted. I just burned it open! - Altera_Forum
One thing to check is the JTAG power supply. Is it suppose to be 3.3V or 2.5V for Cyclone II? Supplying the wrong voltage can damage the JTAG port and the device as well after seeming to work initially. Also when you ohm out the JTAG pins, they may appear to be shorted to GND. If this is the case, the only soln is to replace the FPGA.
--- Quote Start --- I have similar problem too. My on-board JTAG doesn't work anymore after working for several months. I have cyclone II i found the tck net is about 35 ohms to gnd. In both directions. When power is supplied, I get 3.28V on TCK pin, I didn't notice over comsumption. I can still configure with Active Serial Programming. I notice that I have no progress bar but programming is succesfull. But I can't programm flash by Nios II. --- Quote End --- - Altera_Forum
I have similar problem too. My on-board JTAG doesn't work anymore after working for several months. I have cyclone II
i found the tck net is about 35 ohms to gnd. In both directions. When power is supplied, I get 3.28V on TCK pin, I didn't notice over comsumption. I can still configure with Active Serial Programming. I notice that I have no progress bar but programming is succesfull. But I can't programm flash by Nios II. - Altera_Forum
I aslo met the similar problem, the JTAG can work normal several days ago, but now it can't work, I checked the net of the JTAG connector, found the TCK net is about 80 Ohms to GND.
