During development, you can face issues at multiple stages: when building an application, testing it, or during its lifetime. This section has useful information for troubleshooting when you are facing an issue. First, we will cover build errors and then move on to fatal errors reported by the application.
Build errors
Build log
The build log can be found in the build output terminal. The terminal can be displayed by pressing Ctrl + `, or by going to View –> Terminal. The build log is not stored as a single whole after building; instead, it is divided into multiple files.
The build log output can be quite long, so the recommended approach when you face an error is to start with the first Error in the log and then move to the next one. Depending on the type of error you have, fixing one error may lead to multiple new errors appearing.
Troubleshooting procedure
1. Look for error messages.
Start by scanning the build log for lines that begin with the word “error” or “warning.” These lines indicate issues that need your attention. Errors are more critical than warnings and typically prevent the successful compilation of your project.
2. Read the error message.
When you find the error message, read it carefully. The message will contain information about what went wrong, where it went wrong, and possibly a fix for the error. When you have found the line where the error occurred, open the code in that location.
3. Identify the cause of the error.
There are multiple causes for errors that can occur during compilation of the application. We have listed some of the common errors below:
Code issues: Errors related to your application code, such as syntax errors or undefined variables. Check errno.h for understanding system error codes returned by functions at runtime.
Forgotten “;”
Undefined variable
Bracket not closed
Configuration problems: Errors related to how the project is configured, such as missing or incorrect settings in prj.conf or the devicetree.
Missing dependencies: Zephyr is not able to find the referenced libraries or components.
Incompatible components: Errors resulting from incompatible components or conflicting configuration options.
If building for a sysbuild application, remember to check the prj.conf and devicetree for both images. The general layout for sysbuild is shown below. For more information regarding sysbuild, please see the documentation. Sysbuild will also be covered in depth in lesson 8.
After rewriting what appeared to be the problem, rebuild the project and check the output from the build log. Fixing errors in software is an iterative process, and fixing one error can uncover additional errors.
Fatal errors
A fatal error is an error state in which the Zephyr kernel is deemed unrecoverable. When this happens during runtime, it can be hard to figure out what is wrong, as it might be difficult to reproduce. Luckily, there are tools available that can be used if the device experiences a fatal error.
Addr2line
Addr2line is a command-line tool that uses an address in an executable and corresponding debugging information to determine which file name and line number are associated with the address. This can be used to determine where a fatal error occurs. addr2line is part of the GCC package and is installed together with the nRF Connect SDK.
The addr2line command follows a general syntax
Copy
addr2line [options] [addr...]
To use the tool, you need to provide two pieces of information:
one or more addresses to convert.
binary file that contains the symbols for those addresses.
When the application encounters a fatal error, the log output will print the faulting instruction address, which is what will be used as the address to convert.
The binary file to be used is the zephyr.elf file, found in build/zephyr/zephyr.elf of a built application, which contains both the application and the kernel libraries
.elf (executable linkable format) is a file format that contains metadata, symbol information, debug information, memory segmentation, sections and data. The .elf file can be loaded at any memory address by the kernel and adjust the symbols to offsets from the memory address. This is in comparison to a .hex file, which is a text representation of the binary data, with checksums and addresses. A .hex file can be sparse, meaning it can skip over unused memory locations. This means that an .elf file has more information than a .hex file.
For example, the following command will use the zephyr.elf executable and translate the address 0x000045a2 into its source code location. The -e flag is used to specify the name of the binary file
Copy
addr2line-ebuild/zephyr/zephyr.elf0x000045a2
Bash
The output will specify the full path and code line of the source code location. It will look similar to the below example:
-a: shows the address before each translated location.
-f: shows the name of the function containing each location.
-p: makes the output easier for humans to read.
You will practice how to use this tool in exercise 2 of this lesson.
Core dump
In Zephyr, handling core dumps involves capturing the state of a program when it crashes or encounters an error, making it easier to diagnose and debug issues. Core dumps are especially useful in embedded systems development.
When the coredump module is enabled and a fatal error occurs, the CPU registers and memory content are printed or stored, depending on the backend configuration. This core dump data can be fed into a custom-made GDB server as a remote target for GDB (and other GDB-compatible debuggers). The debugger can examine the CPU registers, memory content, and stack.
To use core dumps in Zephyr, you can follow these steps
Core dump support is not enabled by default in Zephyr. To use core dumps in Zephyr, you need to ensure the device does not immediately restart and specify where to store the dump. Add the following lines in prj.conf to ensure the device does not restart:
To store the core dump, specify where in the flash to store the core dump. Zephyr provides several options for core dump storage, including flash memory or an external storage device. This is configured in the prj.conf file:
This will store the core dump in the Flash starting at the offset 0x300000. The offset value will be different for different target devices.
GDB server
The GBDserver is a computer application that makes it possible to debug other applications remotely. Thereafter, the CPU register, memory content, and stack can be examined in the debugger. This normally includes the following steps:
1. Get the core dump log from the device, using the enabled backend. For example, if the log module backend is used, get the log output from the log module backend. 2. Convert the core dump log into a binary format that the GDB server can parse. For example, scripts/coredump/coredump_serial_log_parser.py can be used to convert the serial console log into a binary file. 3. Start the custom GDB server using the script scripts/coredump/coredump_gdbserver.py with the core dump binary log file and the Zephyr ELF file as parameters. 4. Start the debugger corresponding to the target architecture.
v2.6.2 – v2.5.2
During development, you can face issues at multiple stages: when building an application, testing it, or during its lifetime. This section has useful information for troubleshooting when you are facing an issue. First, we will cover build errors and then move on to fatal errors reported by the application.
Build errors
Build log
The build log can be found in the build output terminal. The terminal can be displayed by pressing Ctrl + `, or by going to View –> Terminal. The build log is not stored as a single whole after building, but is instead divided into multiple files.
The build log output can be quite long, so the recommended approach when you face an error is to start with the first Error in the log and then move to the next one. Depending on the type of error you have, fixing one error may lead to multiple new errors appearing.
Troubleshooting procedure
1. Look for error messages. Start by scanning the build log for lines that begin with the word “error” or “warning.” These lines indicate issues that need your attention. Errors are more critical than warnings, and typically prevent the successful compilation of your project.
2. Read the error message. When you find the error message, read it carefully. The message will contain information about what went wrong, where it went wrong, and possibly a fix for the error. When you have found the line where the error occurred, open the code in that location.
3. Identify the cause of the error. There are multiple causes for errors that can occur during compilation of the application. We have listed some of the common errors below:
Code issues: Errors related to your application code, such as syntax errors or undefined variables. Check errno.h for understanding system error codes returned by functions at runtime.
Forgotten “;”
Undefined variable
Bracket not closed
Configuration problems: Errors related to how the project is configured, such as missing or incorrect settings in prj.conf or the devicetree.
Missing dependencies: Zephyr is not able to find the referenced libraries or components.
Incompatible components: Errors resulting from incompatible components or conflicting configuration options.
If building for a multi-image application, remember to check the prj.conf and devicetree for both images. The general layout for a multi-image build is shown below. For more information regarding multi-image builds, please see the documentation.
Copy
# It is possible for a sample to use a custom set of Kconfig fragments for a # child image, or to append additional Kconfig fragments to the child image. # Note that <ACI_NAME> in this context is the name of the child image as # passed to the 'add_child_image' function. # # <child-sample> DIRECTORY # | - prj.conf (A) # | - prj_<buildtype>.conf (B) # | - boards DIRECTORY # | | - <board>.conf (C) # | | - <board>_<buildtype>.conf (D) # <current-sample> DIRECTORY # | - prj.conf # | - prj_<buildtype>.conf # | - child_image DIRECTORY # |-- <ACI_NAME>.conf (I) Fragment, used together with (A) and (C) # |-- <ACI_NAME>_<buildtype>.conf (J) Fragment, used together with (B) and (D) # |-- <ACI_NAME>.overlay If present, will be merged with BOARD.dts # |-- <ACI_NAME> DIRECTORY # |-- boards DIRECTORY # | |-- <board>.conf (E) If present, use instead of (C), requires (G). # | |-- <board>_<buildtype>.conf (F) If present, use instead of (D), requires (H). # | |-- <board>.overlay If present, will be merged with BOARD.dts # | |-- <board>_<revision>.overlay If present, will be merged with BOARD.dts # |-- prj.conf (G) If present, use instead of (A) # | Note that (C) is ignored if this is present. # | Use (E) instead. # |-- prj_<buildtype>.conf (H) If present, used instead of (B) when user # | specify `-DCONF_FILE=prj_<buildtype>.conf for # | parent image. Note that any (C) is ignored # | if this is present. Use (F) instead. # |-- <board>.overlay If present, will be merged with BOARD.dts # |-- <board>_<revision>.overlay If present, will be merged with BOARD.dts # # Note: The folder `child_image/<ACI_NAME>` is only need when configurations # files must be used instead of the child image default configs. # The append a child image default config, place the additional settings # in `child_image/<ACI_NAME>.conf`.
Above is the multi-image application structure for nRF Connect SDK version 2.6.1 or below. This will be covered in depth in lesson 8.
After rewriting what appeared to be the problem, rebuild the project and check the output from the build log. Fixing errors in software is an iterative process, and fixing one error can uncover additional errors.
Fatal errors
A fatal error is an error state where the Zephyr kernel is deemed to be in an unrecoverable state. When this happens during runtime, it can be hard to figure out what is wrong as it might be difficult to reproduce. Luckily, there are tools available that can be used if the device experiences a fatal error.
Addr2line
Addr2line is a command line tool that uses an address in an executable and corresponding debugging information to figure out which file name and line number are associated with the address. This can be used to figure out where a fatal error occurs. addr2line is a part of the GCC package and is installed together with the nRF Connect SDK.
The addr2line command follows a general syntax
Copy
addr2line [options] [addr...]
To use the tool, you need to provide two pieces of information:
one or more addresses to convert.
binary file that contains the symbols for those addresses.
When the application encounters a fatal error, the log output will print the faulting instruction address, which is what will be used as the address to convert.
The binary file to be used is the zephyr.elf file, found in build/zephyr/zephyr.elf of a built application, which contains both the application and the kernel libraries
.elf (executable linkable format) is a file format that contains metadata, symbol information, debug information, memory segmentation, sections and data. The .elf file can be loaded at any memory address by the kernel and adjust the symbols to offsets from the memory address. This is in comparison to a .hex file, which is a text representation of the binary data, with checksums and addresses. A .hex file can be sparse, meaning it can skip over unused memory locations. This means that an .elf file has more information than a .hex file.
For example, the following command will use the zephyr.elf executable and translate the address 0x000045a2 into its source code location. The -e flag is used to specify the name of the binary file
Copy
addr2line-ebuild/zephyr/zephyr.elf0x000045a2
Bash
The output will specify the full path and code line of the source code location. It will look similar to the below example:
-a: shows the address before each translated location.
-f: shows the name of the function containing each location.
-p: makes the output easier for humans to read.
You will practice how to use this tool in exercise 2 of this lesson.
Core dump
In Zephyr, handling core dumps involves capturing the state of a program when it crashes or encounters an error, making it easier to diagnose and debug issues. Core dumps are especially useful in embedded systems development.
When the coredump module is enabled and a fatal error occurs, the CPU registers and memory content are printed or stored, depending on the backend configuration. This core dump data can be fed into a custom-made GDB server as a remote target for GDB (and other GDB-compatible debuggers). CPU registers, memory content and stack can be examined in the debugger.
To use core dumps in Zephyr, you can follow these steps
Core dump support is not enabled by default in Zephyr. To use core dumps in Zephyr, you need to ensure the device does not immediately restart and specify where to store the dump. Add the following lines in prj.conf to ensure the device does not restart:
To store the core dump, specify where in the flash to store the core dump. Zephyr provides several options for core dump storage, including flash memory or an external storage device. This is configured in the prj.conf file:
This will store the core dump in the Flash starting at the offset 0x300000. The offset value will be different for different target devices.
GDB server
The GBDserver is a computer application that makes it possible to debug other applications remotely. Thereafter, the CPU register, memory content, and stack can be examined in the debugger. This normally includes the following steps:
1. Get the core dump log from the device, using the enabled backend. For example, if the log module backend is used, get the log output from the log module backend. 2. Convert the core dump log into a binary format that the GDB server can parse. For example, scripts/coredump/coredump_serial_log_parser.py can be used to convert the serial console log into a binary file. 3. Start the custom GDB server using the script scripts/coredump/coredump_gdbserver.py with the core dump binary log file and the Zephyr ELF file as parameters. 4. Start the debugger corresponding to the target architecture.
Nordic Developer Academy Privacy Policy
1. Introduction
In this Privacy Policy you will find information on Nordic Semiconductor ASA (“Nordic Semiconductor”) processes your personal data when you use the Nordic Developer Academy.
References to “we” and “us” in this document refers to Nordic Semiconductor.
2. Our processing of personal data when you use the Nordic Developer Academy
2.1 Nordic Developer Academy
Nordic Semiconductor processes personal data in order to provide you with the features and functionality of the Nordic Developer Academy. Creating a user account is optional, but required if you want to track you progress and view your completed courses and obtained certificates. If you choose to create a user account, we will process the following categories of personal data:
Email
Name
Password (encrypted)
Course progression (e.g. which course you have completely or partly completed)
Certificate information, which consists of name of completed course and the validity of the certificate
Course results
During your use of the Nordic Developer Academy, you may also be asked if you want to provide feedback. If you choose to respond to any such surveys, we will also process the personal data in your responses in that survey.
The legal basis for this processing is GDPR article 6 (1) b. The processing is necessary for Nordic Semiconductor to provide the Nordic Developer Academy under the Terms of Service.
2.2 Analytics
If you consent to analytics, Nordic Semiconductor will use Google Analytics to obtain statistics about how the Nordic Developer Academy is used. This includes collecting information on for example what pages are viewed, the duration of the visit, the way in which the pages are maneuvered, what links are clicked, technical information about your equipment. The information is used to learn how Nordic Developer Academy is used and how the user experience can be further developed.
2.2 Newsletter
You can consent to receive newsletters from Nordic from within the Nordic Developer Academy. How your personal data is processed when you sign up for our newsletters is described in the Nordic Semiconductor Privacy Policy.
3. Retention period
We will store your personal data for as long you use the Nordic Developer Academy. If our systems register that you have not used your account for 36 months, your account will be deleted.
4. Additional information
Additional information on how we process personal data can be found in the Nordic Semiconductor Privacy Policy and Cookie Policy.
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://academy.nordicsemi.com/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.
