Segger J-Link: JTAG Usage
Summary
This documentation describes the steps necessary to use the Segger J-Link V8 to connect to a device using JTAG. In this example, a BeagleBoard® https://www.beagleboard.org/boards/beagleboard is used.
Requirements
- Target JTAG Device (e.g. BeagleBoard®)
- Compatible cable to connect the target's JTAG pins to the J-Link
- J-Link uses a standard 20-Pin connector compatible to ARM's Multi-ICE.
- Software: J-Link Software and Documentation pack https://www.segger.com/downloads/jlink/
Description
Step 1 - Connect J-Link to PC
Connect the Segger J-Link to the PC using the included cable and start the J-Link Commander. Upon successful detection of the J-Link, a message like the following is shown:
SEGGER J-Link Commander V7.86f (Compiled Mar 29 2023 16:41:57) DLL version V7.86f, compiled Mar 29 2023 16:39:17
Connecting to J-Link via USB...O.K. Firmware: J-Link ARM V8 compiled Nov 28 2014 13:44:46 Hardware version: V8.00 J-Link uptime (since boot): N/A (Not supported by this model) S/N: 788529685 License(s): RDI,FlashDL,FlashBP,JFlash,GDB VTref=3.313V Type "connect" to establish a target connection, '?' for help J-Link>
Step 2 - Connect J-Link to target device
Connect the J-Link to the target device's JTAG pins using an appropriate cable.
In this example, such a cable to connect to the BeagleBoard was not available. Therefore, the pins have been connected manually in the following way:
| BeagleBoard | J-Link |
|---|---|
| 1 - TMS | 7 - TMS |
| 2 - nTRST | 3 - nTRST |
| 3 - TDI | 5 - TDI |
| 4 - GND | 4 - GND |
| 5 - VIO | 1 - VTref |
| 7 - TDO | 13 - TDO |
| 9 - RTCK | 11 - RTCK |
| 11 - TCK | 9 - TCK |
The other pins were not connected.
See https://beagleboard.org/static/BBSRM_latest.pdf (Page 112) for more information about the BeagleBoard's JTAG connector.
Information about the J-Link's pins can be found here: https://www.segger.com/products/debug-probes/j-link/technology/interface-description