J-Link PRO

J-Link PRO is fully compatible with J-Link and can be used “out-of-the-box”. J-Link PRO uses DHCP per default. The built-in web server makes manual configuration easy. Ethernet allows the use of the debug probe far away from the PC, over a hardwired or wireless network, in a development or production environment. It also makes download and debugging speeds higher and provides electrical isolation from the PC. The product also comes with all features of the regular J-Link.

Key features

  • Additional Ethernet interface
  • Download speed up to 4 MB/s
  • Unlimited breakpoints in flash memory (Flash Breakpoints)
  • Use with Ozone, RDI/RDDI and J-Flash
  • Additional LEDs for power and RESET indication
  • Comes with web interface for easy TCP/IP configuration (built-in webserver)
  • Built-in VCOM functionality
  • Supports a broad range of microcontrollers
  • Supports direct download into RAM and flash memory
  • Free software updates


All software is included free of charge. It comes with licenses for all J-Link related SEGGER software products, such as J-Link Unlimited Flash Breakpoints, Ozone, RDI/RDDI, J-Flash, J-Link GDB Server, providing the optimum debugging solution for professional developers.


As a multi-platform solution, J-Link PRO comes with the setup and control software for Linux, macOS and Windows. Software and firmware updates are included. Similarly, use on all currently supported target devices, and any that will be added, is also included.


J-Flash is a part of the J-Link Software and Documentation Package and allows the programming of the internal and external flash memory of a microcontroller-based embedded system via J-Link.


Up to 4 MB/s download speed make J-Link PRO the fastest debug probe on the market. Using TCP/IP instead of USB eliminates latencies from USB usage, resulting in higher debugging speed.


J-Link PRO provides an Ethernet interface as an alternative to USB connection.


Due to the Ethernet interface, long distances between the development PC and the target system are possible. You can set a default gateway for J-Link PRO making it also possible to use it in large intranets.

Safety (galvanic isolation)

Ethernet signal lines provide galvanic isolation of J-Link PRO (and so the target system) from the network and development PC.

Flash Breakpoints

The J-Link PRO comes with an additional feature, called Unlimited Flash Breakpoints. Unlimited Flash Breakpoints allow the user to set an unlimited number of breakpoints when debugging in flash memory.

Ozone — The J-Link debugger

Ozone is the debugger for J-Link and J-Trace. It includes all well-known debug controls and information windows and makes use of the best performance of J-Link and J-Trace debug probes.

Standalone debugger

Ozone focuses on debugging. There are no compiler or project window distractions. All debug windows can be moved, resized and docked, to provide you with the workspace you need.

Ozone offers all well-known debug controls and information windows, and more. Instruction trace, power graph, live watches, and real-time terminal I/O further extend these capabilities.

J Link Pro Standalone Debugger

Debugging with Ozone

Performance analyzer

With J-Link’s High-Speed Sampling technology, Ozone can sample and visualize an embedded system’s variables over time. Checking values and flags in the debugger, while the target keeps running, is easy.

J-Link’s power measurement features enable you to record the power consumption of your target device in a debug session. This is especially helpful when you are developing a low-power device and need to know how power consumption changes when you enable or disable certain components.

J Link Pro Performance Analyzer

Performance analysis with Ozone

Building a test farm with J-Link PRO

The J-Link PRO is ideally suited for the construction of a test farm. Also known as a board farm or a device farm, it consists of a number of boards or devices connected to a network via debug probes. It is an efficient way to share hardware, including with users in remote locations.

For any successful product, as the number of devices to be tested grows, a test farm becomes the only efficient way to ensure quality.

Using SEGGER’s Test Farm Power Adapter, the power supply of test devices can be controlled remotely. This enables automated reboot for the testing process as well as the ability to turn off devices not in use. In combination with the power-saving J-Link PRO, this makes it easy to build energy-efficient, large-scale test farms.

A J-Link PRO test farm can connect many of the same test devices or can connect completely different ones.

J Link Pro Building Test Farm

J-Link Test Farm setup

Wireless debugging/telemetry

The J-Link PRO can be used for a wireless connection between monitoring/debugging PC and the target device. To achieve this, the J-Link PRO needs to be connected to a WiFi router or switch.

Technical specifications

Supported OSMicrosoft Windows (x86/x64), Linux (x86/x64/Arm), macOS (x86/Apple Silicon)
Electromagnetic compatibility (EMC)EN 55022, EN 55024
Operating temperature+5°C … +60°C
Storage temperature-20°C … +65 °C
Relative humidity (non-condensing)Max. 90% rH
Size (without cables)100mm x 53mm x 27mm
Weight (without cables)73g
Available interfaces
USB interfaceUSB 2.0 (Hi-Speed)
Target interfaceJTAG/SWD 20-pin
JTAG/SWD interface, electrical
Target interface voltage (VIF)1.2V … 5V
Current drawn from target voltage sense pin (VTRef)< 25µA
Target supply voltage5V (derived from USB voltage)
Target supply currentMax. 300mA
Reset typeOpen drain. Can be pulled low or tristated
Reset low level output voltageVOL <= 10% of VIF
For the whole target voltage range (1.2V <= VIF <= 5V)
LOW level input voltage (VIL)VIL <= 40% of VIF
HIGH level input voltage (VIH)VIH >= 60% of VIF
For 1.2V >= VIF <= 3.6V
LOW level output voltage (VOL) with a load of 10 kOhmVOL <= 20% of VIF
HIGH level output voltage (VOH) with a load of 10 kOhmVOH >= 80% of VIF
For 3.6 <= VIF <= 5V
LOW level output voltage (VOL) with a load of 10 kOhmVOL <= 20% of VIF
HIGH level output voltage (VOH) with a load of 10 kOhmVOH >= 80% of VIF
JTAG/SWD interface, timing
Target interface speedMax. 50 MHz
SWO sampling frequencyMax. 100 MHz
Data input rise time (Trdi)Trdi <= 20ns
Data input fall time (Tfdi)Tfdi <= 20ns
Data output rise time (Trdo)Trdo <= 10ns
Data output fall time (Tfdo)Tfdo <= 10ns
Clock rise time (Trc)Trc <= 3ns
Clock fall time (Tfc)Trc <= 3ns
Analog power measurement interface
Sampling frequency200 kHz
Resolution50 uA

Package content

Ethernet Cable
20Pin Target Ribbon
USB Cable

J-Link PRO

Ethernet cable

20-pin, 0.1″ target ribbon cable

USB cable