Eclipse Jlink

Debugging with Eclipse and J-Link

This topic explains how to setup and use MCU Eclipse with a Segger Jlink adapter to debug PX4 running on NuttX (e.g. Pixhawk series boards).

Required Hardware

• J-Link EDU Mini
• Adapter to connect Segger JLink to Flight Controller SWD Debug Port (debug port).
• Micro USB cable

Installation

PX4

Setup PX4 by following the normal guidelines:

• Setup the PX4 Developer Environment/Toolchain for your platform (e.g. for Linux see: Development Environment on Ubuntu LTS / Debian Linux).
• Download PX4 and optionally build it on the command line.

Eclipse

To install Eclipse:

1. Download Eclipse CDT for C/C++ Developers (MCU GitHub).
2. Extract the Eclipse folder and copy it anywhere (there is no need to run any install scripts).
3. Run Eclipse and choose a location for your initial workbench.

Segger Jlink Tools

To install the Segger Jlink tools:

1. Download and run the J-Link Software and Documentation Pack for your OS (Windows and Linux packages available).
2. On Linux the tools are installed in /usr/bin.

For more information, see: https://gnu-mcu-eclipse.github.io/debug/jlink/install/.

First Use

1. Connect the Segger JLink to the host computer and the flight controller debug port (via an adapter).
2. Power the flight controller.
3. Run Eclipse.
4. Add a source by choosing File > Import > C/C++ > Existing Code as Makefile Project and click Next.
5. Point it to the PX4-Autopilot folder and give it a name, then select ARM Cross GCC in the Toolchain for Indexer Settings and click Finish. Import takes a while, wait for it to complete.
6. Set the MCU settings: right-click on the top-level project in the Project Explorer, select Properties then under MCU choose SEGGER J-Link Path. Set it as shown in the screenshot below.

7. Update packs:

8. Click the small icon on the top right called Open Perspective and open the Packs perspective.

9. Click the update all button.

   :::tip This takes a VERY LONG TIME (10 minutes). Ignore all the errors about missing packages that pop up. :::

   

10. The STM32Fxx devices are found in the Keil folder, install by right-clicking and then selecting install on the according device for F4 and F7.

11. Setup debug configuration for target:

12. Right click project and open the Settings (menu: C/C++ Build > Settings)

13. Choose the Devices Tab, Devices section (Not Boards).
14. Find the FMU chip you wish to debug.

1. Select debug configurations with the small drop-down next to the bug symbol:
2. Then select GDB SEGGER J-Link Debugging and then the New config button on the top left.

3. Setup build config:

4. Give it a name and set the C/C++ Application to the corresponding .elf file.

5. Choose Disable Auto build

   ::: info Remember that you must build the target from the command line before starting a debug session. :::

1. The Debugger and Startup tabs shouldn’t need any modifications (just verify your settings with the screenshots below)

SEGGER Task-aware debugging

Task-aware debugging (also known as thread-aware debugging) allows you to show the context of all running threads/tasks instead of just the stack current task. This is quite useful since PX4 tends to run many different tasks.

To enable this feature for use in Eclipse:

1. You first need to enable CONFIG_DEBUG_TCBINFO in the NuttX configuration for your build (to expose the TCB offsets).

2. Open a terminal in the root of your PX4-Autopilot source code

3. In the terminal, open menuconfig using the appropriate make target for the build. This will be something like:

   sh make px4_fmu-v5_default boardguiconfig

   (See PX4 Menuconfig Setup for more information) on using the config tools).

4. Ensure that the Enable TCBinfo struct for debug is selected as shown:

5. Compile the jlink-nuttx.so library in the terminal by running the following command in the terminal: make jlink-nuttx

6. Modify Eclipse to use this libary. In the J-Link GDB Server Setup configuration, update Other options to include -rtos /home/<PX4 path>/Tools/jlink-nuttx.so, as shown in the image below.

1. When running the debugger you should see now multiple threads instead of just one:

Troubleshooting

Target CPU not in Package Manager

If the target CPU does not appear in the package manager you may need these steps to get the register view working.

:::tip This should not generally happen (but anecdotally has been reported when connecting to an STM F7 controller). :::

Adding missing SVD files for the Peripheral View:

1. Find out where MCU Eclipse stores its packages (Preferences > C/C++ > MCU Packages):

1. Download missing packages from: http://www.keil.com/dd2/Pack/
2. Open downloaded pack with a decompression tool, and extract the .SVD files from: /CMSIS/SVD.
3. Select desired .SVD file in: Debug Options > GDB SEGGER JLink Debugging > SVD Path