Segger J-Link - Troubleshooting

J-Link / J-Trace (UM08001) © 2004-2017 SEGGER Microcontroller GmbH & Co. KG
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20.2 Troubleshooting
20.2.1 General procedure
If you experience problems with J-Link / J-Trace, you should follow the steps below to
solve these problems:
1. Close all running applications on your host system.
2. Disconnect the J-Link / J-Trace device from USB.
3. Disable power supply on the target.
4. Re-connect J-Link / J-Trace with the host system (attach USB cable).
5. Enable power supply on the target.
6. Try your target application again. If the problem remains continue the following
procedure.
7. Close all running applications on your host system again.
8. Disconnect the J-Link / J-Trace device from USB.
9. Disable power supply on the target.
10. Re-connect J-Link / J-Trace with the host system (attach the USB cable).
11. Enable power supply on the target.
12. Start
JLink.exe.
13. If
JLink.exe displays the J-Link / J-Trace serial number and the target proces-
sor’s core ID, the J-Link / J-Trace is working properly and cannot be the cause of
your problem.
14. If the problem persists and you own an original product (not an OEM version),
see section
Contacting support on page 469.
20.2.2 Typical problem scenarios
J-Link / J-Trace LED is off
Meaning:
The USB connection does not work.
Remedy:
Check the USB connection. Try to re-initialize J-Link / J-Trace by disconnecting and
reconnecting it. Make sure that the connectors are firmly attached. Check the cable
connections on your J-Link / J-Trace and the host computer. If this does not solve the
problem, check if your cable is defective. If the USB cable is ok, try a different host
computer.
J-Link / J-Trace LED is flashing at a high frequency
Meaning:
J-Link / J-Trace could not be enumerated by the USB controller.
Most likely reasons:
a.) Another program is already using J-Link / J-Trace.
b.) The J-Link USB driver does not work correctly.
Remedy:
a.) Close all running applications and try to reinitialize J-Link / J-Trace by disconnect-
ing and reconnecting it.
b.) If the LED blinks permanently, check the correct installation of the J-Link USB
driver. Deinstall and reinstall the driver as shown in chapter
Setup on page 157.