JTAG Chain Broken – Unable to Program Agilex 5 Modular Development Board

[Ganeshz]

Dear Intel FPGA Support Team,

I am currently working with the Agilex™ 5 Modular Development Kit. Upon initial setup, the board functioned as expected. We successfully ran the Built-In Self-Test (BIST), and subsequently programmed the board with official Intel demonstration .sof files via JTAG without issue.

However, on the following day, the board suddenly became unresponsive to JTAG programming. The Quartus Programmer now reports the following error:

Info (213045): Using programming cable "Agilex_5E MDK Carrier [1-2.1]"
1) Agilex_5E MDK Carrier [1-2.1]
Unable to read device chain – JTAG chain broken

This issue occurred without any change in hardware setup or configuration. It is unexpected and has blocked further development.

Actions Taken:

• Verified switch settings S13, S7, and S4 as per the Quick Start Guide.

• Retried with multiple .sof files and different versions of Quartus.

• Reconnected and tested the JTAG micro-USB cable, including using a known-working cable and port.

• Powered cycle and rechecked all board connections.

• Confirmed that the same error appears consistently across multiple host systems.

Request:

We kindly request your assistance in identifying the root cause of this sudden JTAG chain failure. Please advise on the recommended next steps for debugging or recovering the JTAG interface.

We have attached a screenshot of the Quartus Programmer and JTAG Chain Debugger for your reference.

Looking forward to your support to help restore JTAG programming capability on the Agilex 5 MDK.

Best regards,

Ganesh

[Farabi]

Hello,

Can you use Quartus configuration debugger to see if the device power up successfully? (attached config debugger status)

regards,

Farabi

[Farabi]

[Ganeshz]

Hi Farabi, 

Thanks for your reply. Find captured. 

We observed that if we keep the auto-adjust frequency at chain scanning, then we are not able to scan the device. 

Also, if we keep the hardware frequency low 16/6MHz then we are able to program Agilex5 as expected. But after programming, if we want to access the JTAG port from Python code, then it is not accessible every time and throws JTAG chain broken error.

[Fakhrul]

As we haven't received a response to our previous notification, this thread will be transitioned to community support. We hope all your concerns have been addressed. If you have any new questions, please feel free to open a new thread to receive support from Intel experts. Otherwise, community users will continue to assist you here. Thank you.