Difference between revisions of "Segger J-Link: JTAG Usage"
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J-Link supports many different devices/CPUs already. The BeagleBoard however requires a custom configuration script which can be found here: https://github.com/nullsub/sidplayer/blob/master/jlinkserver/Samples/JLink/Scripts/ScriptBeagleBoard_OMAP3530.JLinkScript | J-Link supports many different devices/CPUs already. The BeagleBoard however requires a custom configuration script which can be found here: https://github.com/nullsub/sidplayer/blob/master/jlinkserver/Samples/JLink/Scripts/ScriptBeagleBoard_OMAP3530.JLinkScript | ||
This script requires a little modification before it can be used. Some variables are declared as type __int64. This type was only available up to version 6.16 of the J-Link Software. For the usage in newer version it can be replaced with U32. Although the name __int64 might suggest that it stores 64-bit values, according to https://forum.segger.com/index.php/Thread/4189-SOLVED-JLinkScript-and-int64/?postID=15018#post15018 it was internally handled as 32-bit, so these changes should have no effect on the script. | This script requires a little modification before it can be used. Some variables are declared as type <code>__int64</code>. This type was only available up to version 6.16 of the J-Link Software. For the usage in newer version it can be replaced with <code>U32</code>. Although the name <code>__int64</code> might suggest that it stores 64-bit values, according to https://forum.segger.com/index.php/Thread/4189-SOLVED-JLinkScript-and-int64/?postID=15018#post15018 it was internally handled as 32-bit, so these changes should have no effect on the script. | ||
The modified script has to be saved in the installation directory as | The modified script has to be saved in the installation directory as <code>Default.JLinkScript</code>. | ||
Power the target device and connect the J-Link to the PC (if not already connected) and start the J-Link Commander. An output similar to the one shown in Step 1 should be shown again. Type <code>connect</code> and then specify the target device / core. For the BeagleBoard type <code>CORTEX-A8</code>. For the other settings keep the default values. After connecting it is possible to run commands like <code>halt</code> to halt the cpu, <code>go</code> to resume, etc. A list of commands can be found by typing <code>?</code>. | |||
== Used Hardware == | == Used Hardware == | ||
Revision as of 12:44, 20 April 2023
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
Step 3 - Connect using J-Link Commander
J-Link supports many different devices/CPUs already. The BeagleBoard however requires a custom configuration script which can be found here: https://github.com/nullsub/sidplayer/blob/master/jlinkserver/Samples/JLink/Scripts/ScriptBeagleBoard_OMAP3530.JLinkScript
This script requires a little modification before it can be used. Some variables are declared as type __int64. This type was only available up to version 6.16 of the J-Link Software. For the usage in newer version it can be replaced with U32. Although the name __int64 might suggest that it stores 64-bit values, according to https://forum.segger.com/index.php/Thread/4189-SOLVED-JLinkScript-and-int64/?postID=15018#post15018 it was internally handled as 32-bit, so these changes should have no effect on the script.
The modified script has to be saved in the installation directory as Default.JLinkScript.
Power the target device and connect the J-Link to the PC (if not already connected) and start the J-Link Commander. An output similar to the one shown in Step 1 should be shown again. Type connect and then specify the target device / core. For the BeagleBoard type CORTEX-A8. For the other settings keep the default values. After connecting it is possible to run commands like halt to halt the cpu, go to resume, etc. A list of commands can be found by typing ?.