Feedback

Debugging in nRF Connect for VS Code

Debugging, in the context of embedded development, is the process of identifying, analyzing and resolving issues related to software and hardware. Debugging is an iterative process where the developer analyzes the code or hardware and makes small adjustments before they test their application again. Common problems you might face during development are syntax errors, logical errors, memory leaks, timing issues, and hardware-related issues.

The nRF Connect SDK has multiple tools that can help when debugging your application. In this chapter, we will go through some of the most useful debugging tools and how to use them.

Preparing for debugging

To be able to debug your nRF Connect SDK application, you must configure it correctly before building.

In the build configuration menu, under Optimization level, select the option Optimize for debugging. This option enables additional extension-specific debugging features after the application is built.

When this optimization is set, the following Kconfigs are enabled in the build:

CONFIG_DEBUG_OPTIMIZATIONS – Limits the optimizations done by the compiler to only those that do not impact debugging.
CONFIG_DEBUG_THREAD_INFO – Adds additional information to the thread object so the debugger can discover the threads.

Other Kconfigs that can be useful when debugging:

CONFIG_I2C_DUMP_MESSAGES – Enables the possibility to log all I2C messages. See Debugging I2C communication for more information.
CONFIG_ASSERT – This enables the __ASSERT() macro in the kernel code. If an assertion fails, the policy for what to do is controlled by the implementation of the assert_post_action() function, which by default will trigger a fatal error.

It’s worth taking into consideration that enabling optimization for debugging will affect the size of the code, and this can cause errors. If this is a problem, enabling only what is needed from the default optimization for debugging might be used; for example CONFIG_THREAD_NAME or CONFIG_DEBUG. There are also additional Kconfigs for different network stacks.

Pristine Build

Outputs are created at CMake configuration time and are not always regenerated when one of their inputs changes. As a first step in getting the build compiled, it is recommended to delete the build folder and do a pristine build manually.

Breakpoints

A breakpoint is a place in the code where you want the instruction to pause the execution of the application when the selected point is reached. This allows you to examine the program state and variable values or look at the call stack at that point of execution. The breakpoints are normally set at the line where you would like the application to halt its execution.

In VS Code, one can set conditional breakpoints, so the breakpoint occurs when reaching a specific expression or function. It is also possible to print a log statement instead of stopping at the breakpoint. To change the type of breakpoint, either right-click on an existing breakpoint and select Edit breakpoint or right-click on the line number and add a desired type of breakpoint.

Monitor mode debugging

The debugger can run in two modes: halt mode and monitor mode.

In halt mode, the debugger halts the CPU when a debug request occurs, while in monitor mode, the debugger lets the CPU debug parts of an application while crucial functions continue. Monitor mode is useful for timing-critical applications like Bluetooth Low Energy or PWM, where halting the entire application will affect the timing-critical aspects. The CPU takes debug interrupts, running a monitor code for J-Link communication and user-defined functions. The Logpoint can be used together with monitor mode to provide debug information without crashing the application.

To enable monitor mode for the application, do the following:

In the application configuration file, enable the Kconfig options CONFIG_CORTEX_M_DEBUG_MONITOR_HOOK and CONFIG_SEGGER_DEBUGMON.
Enable monitor mode for the debugger you are using. For nRF Debug in nRF Connect for VS Code extension, enter -exec monitor exec SetMonModeDebug=1 in the debug console to enable monitor mode.

Variables view

The Variables view shows variables in the current scope and organizes them into local, global, and static sections. The variables are only updated when the application is halted.

Example view of the variables overview in VS Code

Watch View

The Watch View shows the output of variables you have selected to watch.

To start watching a variable:

Click and drag the mouse cursor to highlight the variable in your code.
Right-click and choose Add to Watch.
Click the Start/Continue button in the debugging control bar to watch the debugger go through the code until it stops at the variable breakpoint.
The output of the code displays in the Watch View

Example view of user-inputted variables you wish to keep an eye on

Peripherals View

When debugging starts, the debugger shows a memory map of peripherals from your device’s SVD file and displays the values of their registers and fields. You can use this information to monitor and troubleshoot your hardware behavior.

Short example view of the peripherals of an nRF52840

Call stack

The call stack lists all of the available threads and indicates which ones are running. It also includes the call stack for each thread that is running. The call stack is a data structure that keeps track of function calls within an application. A stack is a kernel object that implements a Last-In-First-Out (LIFO) queue. This allows threads and ISRs to add and remove a limited number of integer data values. More about stacks can be found here.

Thread Viewer

Thread overview of an example application

The Thread Viewer shows you information about the specific threads in the application. Their state uses Zephyr’s thread states and is only updated when the debugger is stopped. While the device is running, the View is frozen. Any state in the table is stale until execution is stopped again.

Name – Name of the thread.
Priority – Priority of the thread configured by the user, based on Zephyr’s thread priorities.
Entry – Name of the thread entry point function in the code.
Stack Usage – Number of bytes used by the thread and the maximum number of bytes that can be allocated to the thread.
User Option – Binary value associated with the thread. The numbers in this column represent bit fields which are based on Zephyr’s thread options. Colors are for readability only.

Memory Explorer

The Memory Explorer shows the memory content on your device. You can review different regions of memory data in its data and text tabs. More information about what you can do in this view can be found here.

Nordic Developer Academy Terms of Service

1. Introduction

‍These terms and conditions (“Terms of Use”) apply to the use of the Nordic Developer Academy, provided by Nordic Semiconductor ASA, org. nr. 966 011 726, a public limited liability company registered in Norway (“Nordic Semiconductor”). ‍

Nordic Developer Academy allows the user to take technical courses related to Nordic Semiconductor products, software and services, and obtain a certificate certifying completion of these courses. By completing the registration process for the Nordic Developer Academy, you are agreeing to be bound by these Terms of Use.

These Terms of Use are applicable as long as you have a user account giving you access to Nordic Developer Academy.‍

‍2. Access to and use of Nordic Developer Academy

‍‍Upon acceptance of these Terms of Use you are granted a non-exclusive right of access to, and use of Nordic Developer Academy, as it is provided to you at any time. Nordic Semiconductor provides Nordic Developer Academy to you free of charge, subject to the provisions of these Terms of Use and the Nordic Developer Academy Privacy Policy.

To access select features of Nordic Developer Academy, you need to create a user account. You are solely responsible for the security associated with your user account, including always keeping your login details safe.

You will able to receive an electronic certificate from Nordic Developer Academy upon completion of courses. By issuing you such a certificate, Nordic Semiconductor certifies that you have completed the applicable course, but does not provide any further warrants or endorsements for any particular skills or professional qualifications.

Nordic Semiconductor will continuously develop Nordic Developer Academy with new features and functionality, but reserves the right to remove or alter any existing functions without notice.

‍3. Acceptable use

You undertake that you will use Nordic Developer Academy in accordance with applicable law and regulations, and in accordance with these Terms of Use.‍ You must not modify, adapt, or hack Nordic Developer Academy or modify another website so as to falsely imply that it is associated with Nordic Developer Academy, Nordic Semiconductor, or any other Nordic Semiconductor product, software or service.

You agree not to reproduce, duplicate, copy, sell, resell or in any other way exploit any portion of Nordic Developer Academy, use of Nordic Developer Academy, or access to Nordic Developer Academy without the express written permission by Nordic Semiconductor. You must not upload, post, host, or transmit unsolicited email, SMS, or \”spam\” messages.

You are responsible for ensuring that the information you post and the content you share does not;

contain false, misleading or otherwise erroneous information
infringe someone else’s copyrights or other intellectual property rights
contain sensitive personal data or
contain information that might be received as offensive or insulting.
Such information may be removed without prior notice.

‍Nordic Semiconductor reserves the right to at any time determine whether a use of Nordic Developer Academy is in violation of its requirements for acceptable use.

Violation of the at any time applicable requirements for acceptable use may result in termination of your account. We will take reasonable steps to notify you and state the reason for termination in such cases.

‍4. Routines for planned maintenance

‍Certain types of maintenance may imply a stop or reduction in availability of Nordic Developer Academy. Nordic Semiconductor does not warrant any level of service availability but will provide its best effort to limit the impact of any planned maintenance on the availability of Nordic Developer Academy.

5. Intellectual property rights

‍Nordic Semiconductor retains all rights to all elements of Nordic Developer Academy. This includes, but is not limited to, the concept, design, trademarks, know-how, trade secrets, copyrights and all other intellectual property rights.

Nordic Semiconductor receives all rights to all content uploaded or created in Nordic Developer Academy. You do not receive any license or usage rights to Nordic Developer Academy beyond what is explicitly stated in this Agreement.

‍6. Liability and damages

‍Nothing within these Terms of Use is intended to limit your statutory data privacy rights as a data subject, as described in the Nordic Developer Academy Privacy Policy. ‍You acknowledge that errors might occur from time to time and waive any right to claim for compensation as a result of errors in Nordic Developer Academy. When an error occurs, you shall notify Nordic Semiconductor of the error and provide a description of the error situation.

You agree to indemnify Nordic Semiconductor for any loss, including indirect loss, arising out of or in connection with your use of Nordic Developer Academy or violations of these Terms of Use. ‍Nordic Semiconductor shall not be held liable for, and does not warrant that (i) Nordic Developer Academy will meet your specific requirements, (ii) Nordic Developer Academy will be uninterrupted, timely, secure, or error-free, (iii) the results that may be obtained from the use of Nordic Developer Academy will be accurate or reliable, (iv) the quality of any products, services, information, or other material purchased or obtained by you through Nordic Developer Academy will meet your expectations, or that (v) any errors in Nordic Developer Academy will be corrected.

You accept that this is a service provided to you without any payment and hence you accept that Nordic Semiconductor will not be held responsible, or liable, for any breaches of these Terms of Use or any loss connected to your use of Nordic Developer Academy. Unless otherwise follows from mandatory law, Nordic Semiconductor will not accept any such responsibility or liability.

‍7. Change of terms

‍Nordic Semiconductor may update and change the Terms of Use from time to time. Nordic Semiconductor will seek to notify you about significant changes before such changes come into force and give you a possibility to evaluate the effects of proposed changes. Continued use of Nordic Developer Academy after any such changes shall constitute your acceptance of such changes. You can review the current version of the Terms of Use at any time at https://devacademynewclone426.kinsta.cloud/terms-of-service/

‍8. Transfer of rights

‍Nordic Semiconductor is entitled to transfer its rights and obligation pursuant to these Terms of Use to a third party as part of a merger or acquisition process, or as a result of other organizational changes.

‍9. Third Party Services

‍‍To the extent Nordic Developer Academy facilitates access to services provided by a third party, you agree to comply with the terms governing such third party services. Nordic Semiconductor shall not be held liable for any errors, omissions, inaccuracies, etc. related to such third party services.

‍10. Dispute resolution

‍‍The Terms of Use and any other legally binding agreement between yourself and Nordic Semiconductor shall be subject to Norwegian law and Norwegian courts’ exclusive jurisdiction.