OpenOCD

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About

OpenOCD is a open and free project to support different debug probes under one "API".

Using J-Link with OpenOCD

In general, it is possible to use J-Link with OpenOCD. OpenOCD handles J-Link as a dumb JTAG/SWD/... probe and only uses the very low level logic to output JTAG/SWD/... sequences. It does not make use of any high level logic etc. and therefore is much slower than the proprietary SEGGER J-Link DLL / GDBServer / ... implementation. In order to use J-Link with OpenOCD the standard J-Link USB driver must be replaced with the WinUSB driver, using 3rd party utilities. There are lots of walkthroughs available on the internet.

Note: Once the J-Link USB driver has been replaced, no SEGGER software from the J-Link software package will be able to communicate with J-Link anymore. To use SEGGER J-Link software again, the USB driver needs to be switched back to its default.

Limitations

There are several limitations that apply when using J-Link with OpenOCD instead of the SEGGER J-Link software:

  • Much slower than using J-Link with the SEGGER J-Link DLL
  • No RTT support
  • No HSS support
  • No unlimited flash breakpoints support
  • No support for any utilities from the SEGGER J-Link software package
  • No support from SEGGER

Support

Please understand that SEGGER does not provide any support for J-Links used with OpenOCD. The OpenOCD software is released and maintained by a 3rd party. In order to get support, we recommend to get in touch with the OpenOCD community.