# Debugging with Eclipse
This topic explains how to setup and use [MCU Eclipse](https://gnu-mcu-eclipse.github.io/) with a *Segger Jlink adapter* to debug PX4 running on NuttX (e.g. Pixhawk series boards).
## Required Hardware
* [J-Link EDU Mini](https://www.segger.com/products/debug-probes/j-link/models/j-link-edu-mini/)
* Adapter to connect Segger JLink to Flight Controller [SWD Debug Port](https://px4.gitbook.io/px4-user-guide/development/debug/gdb_debugging/swd_debug) (debug port).
* Micro USB cable
## Installation
### PX4
Setup PX4 by following the normal guidelines:
* [Setup the PX4 Developer Environment/Toolchain](https://px4.gitbook.io/px4-user-guide/development/getting_started/dev_env) for your platform (e.g. for Linux see: [Development Environment on Ubuntu LTS / Debian Linux](https://px4.gitbook.io/px4-user-guide/development/getting_started/dev_env/dev_env_linux_ubuntu)).
* [Download PX4](https://px4.gitbook.io/px4-user-guide/development/getting_started/building_px4) and optionally build it on the command line.
### Eclipse
To install *Eclipse*:
1. Download [Eclipse CDT for C/C++ Developers](https://github.com/gnu-mcu-eclipse/org.eclipse.epp.packages/releases/) (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](https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPack) for your OS (Windows and Linux packages available).
* On Linux the tools are installed in **/usr/bin**.
For more information, see: .
## First Use
1. Connect the *Segger JLink* to the host computer and the [flight controller debug port](https://px4.gitbook.io/px4-user-guide/development/debug/gdb_debugging/swd_debug) (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:
* Click the small icon on the top right called *Open Perspective* and open the *Packs* perspective. 
* Click the **update all** button.
:::tip This takes a VERY LONG TIME (10 minutes). Ignore all the errors about missing packages that pop up. :::
* 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.
8. Setup debug configuration for target:
* Right click project and open the *Settings* (menu: **C/C++ Build > Settings**)
* Choose the *Devices* Tab, *Devices* section (Not *Boards*).
* Find the FMU chip you wish to debug.
9. Select debug configurations with the small drop-down next to the bug symbol: 
10. Then select *GDB SEGGER J-Link Debugging* and then the **New config** button on the top left. 
11. Setup build config:
* Give it a name and set the *C/C++ Application* to the corresponding **.elf** file.
* Choose *Disable Auto build* :::note Remember that you must build the target from the command line before starting a debug session. :::
12. 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](https://www.segger.com/products/debug-probes/j-link/tools/j-link-gdb-server/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).
* Open a terminal in the root of your PX4-Autopilot source code
* In the terminal, open `menuconfig` using the appropriate make target for the build. This will be something like:
```
make px4_fmu-v5_default boardguiconfig
```
(See [PX4 Menuconfig Setup](https://px4.gitbook.io/px4-user-guide/hardware/porting_guide/porting_guide_config#px4-menuconfig-setup) for more information) on using the config tools).
* Ensure that the *Enable TCBinfo struct for debug* is selected as shown: 
2. Compile the **jlink-nuttx.so** library in the terminal by running the following command in the terminal: `make jlink-nuttx`
3. Modify Eclipse to use this libary. In the *J-Link GDB Server Setup* configuration, update **Other options** to include `-rtos /home//Tools/jlink-nuttx.so`, as shown in the image below.
4. 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**): 
2. Download missing packages from:
3. Open downloaded pack with a decompression tool, and extract the **.SVD** files from: **/CMSIS/SVD**.
4. Select desired **.SVD** file in: **Debug Options > GDB SEGGER JLink Debugging > SVD Path** 