MAX 10 Jtag Problem

[Altera_Forum]

Dear Good people 

 My MAX 10 JTAG was working well but suddenly from yesterday it is showing some problem. When i push the button auto scan it is showing "Unable to scan device, Cant scan JTAG chain". After thar i tried to debug with JTAG Chain debugger and it showed 3 error message. 1.Error: JTAG chain problem detected 2.Error: The TDI connection to the first detected device UNKNOWN_20D10DD might be shorted to VCC or is an open circuit 3.Error: The TCK and TMS connections to the device before the first detected device UNKNOWN_20D10DD might have a problem  My development board is MAX 10M50DAF484C6GES. I have seen some thread regarding the same problem but could not figure out what they were exactly saying. It would be great to have some specific solution or advice. Thanks in advance

[Altera_Forum]

Did you accidentally enable JTAG pin sharing? Is your JTAGen high or low?

[Altera_Forum]

Hi Vinhael Thanks for your reply. Yes i accidentally enable JTAG pin sharing once. But after that i disable it. I am not sure which one is JTAGen but in my configuration settings CONFIG_SEL pin is enabled. Also in system programming clamp state is low. I tried different ways to resolve it but could not. It would be great if you can give me a solution which i can try. Thanks in advance

[Altera_Forum]

There is another problem i recognize today that in my USB port of development board, 1 pin out of 5 is tilted. Maybe this is the main problem not to scan my device. Need your advice and support.

[Altera_Forum]

You can try to pull nconfig/nstatus low to prevent the internal configuration from occurring. Then auto detect your device in Quartus programmer. If you successfully detect it then tick on the erase column. Your Max 10 should be empty after the erase and you will be able to detect your jtag as normal :)

[Altera_Forum]

Sorry for my understanding, I only find nconfig and nstatus option in Device option of quartus software. In general button there are several options where one option is enable nconfig,nstatus. I tried with enable and disable but could not scan the device. Am i missing something?

[Altera_Forum]

Hi vinhael, I tried what you said...But still it is showing the same problem. Do you have any other advice? would appreciate your help.

[Altera_Forum]

there is a bug on Quartus, so you need to affect TDO and use it as OUTPUT only; 

 from ALTERA/Support  "Why can’t I access the MAX 10 device via JTAG even though JTAGEN is pulled high in user mode?" https://www.altera.com/support/support-resources/knowledge-base/solutions/rd03222016_95.html  "How do I gain access to the JTAG pins of my MAX 10 device if I have enabled the JTAG pin sharing option, and the Quartus Prime Programmer is unable to auto detect the device?" https://www.altera.com/support/support-resources/knowledge-base/solutions/rd05192016_963.html