I have a J-Link Ultra that would previously connect with my STM32 target. Although, the J-Link always seemed to have trouble powering up. When the USB Type B connector was plugged into the J-Link, the Main LED would often come up with a solid red indication. The way that the USB connector was plugged in greatly affected the power-up performance of the J-Link. After much experimentation, it was discovered that the J-Link would power up without a fault almost every time if the USB Type B connector was plugged into the J-Link first, then the Type A connector was plugged into the PC last. This worked fine for a couple of weeks. The J-Link and target would connect, download, and debug as expected.



Now, it is difficult to get the J-Link to power up at all without a fault. However, after many attempts I still get it to power up with a Green Main LED. However, when I try to download my application with IAR Workbench, I get an error message that says it can't connect. At this point, the Main LED on the J-Link flashes red 3 times quickly, pauses 1 second, then repeats. Is this an error code ? This doesn't seem to be documented anywhere.



Of course, I've replaced cables, restarted the computer, etc. It also doesn't seem to matter whether or not the JTAG cable is connected to the target board or not (for the power up problem). Also, the J-Link Arm 4.46 application won't connect with the J-Link either. When connection is attempted, the same 3 red LED blinks is obtained, and the application reports that it is unable to connect.



The target seems to be working fine because it's running the last application code that was downloaded.



Is the J-Link hardware damaged in some way ? If so, how ? Nothing extraordinary happened during debugging. Can the J-Link Ultra be returned to the factory for analysis/repair ?



FYI - I am using the SWD interface instead of full JTAG.