Over-the-air firmware update using HTTPS

This code example demonstrates an over-the-air (OTA) update with PSoC™ 6 or XMC7000 MCU and AIROC™ CYW43xxx Wi-Fi & Bluetooth® combo chips. The device establishes a connection with the designated HTTPS server (this example uses HTTPS local server). It periodically checks the job document to see if a new update is available. When a new update is available, it is downloaded and written to the secondary slot (flash). On the next reboot, MCUboot handles image authentication and upgrades. The upgrade can be either overwrite-based or swap-based. In an overwrite-based upgrade, the new image from the secondary slot is simply copied to the primary slot after successful validation. There is no way to revert the upgrade if the new image is inoperable. In a swap-based upgrade, images in the primary and secondary slots are swapped. The upgrade can be reverted if the new image does not confirm its operation.

MCUboot is a "secure" bootloader for 32-bit MCUs. See the README of the mtb-example-mcuboot-basic code example for more details.

Over-the-air update middleware library enables the OTA feature. See the ota-update middleware repository on Github for more details.

The ota-update middleware can function independently and work with any bootloader, as long as the required OTA update handling storage APIs are implemented and registered with OTA agent by the user. This example enables the MCUboot support with the help of ota-bootloader-abstraction middleware. See README of the ota-bootloader-abstraction middleware for more details.

Users should build the MCUboot-based bootloader application outside of the OTA HTTPS application. It is programmed separately to the device before flashing the OTA HTTPS application and is not updated for the life of the device.

View this README on GitHub.

Provide feedback on this code example.

Requirements

ModusToolbox™ v3.1 or later (tested with v3.2)
Board support package (BSP) minimum required version: 4.0.0
Programming language: C
Associated parts: All PSoC™ 6 MCU parts with SDIO interface, XMC7000 MCU, AIROC™ CYW43012 Wi-Fi & Bluetooth® combo chip, AIROC™ CYW4343W Wi-Fi & Bluetooth® combo chip, AIROC™ CYW4373 Wi-Fi & Bluetooth® combo chip, AIROC™ CYW43439 Wi-Fi & Bluetooth® combo chip

Supported toolchains (make variable 'TOOLCHAIN')

GNU Arm® embedded compiler v11.3.1 (GCC_ARM) - Default value of TOOLCHAIN
Arm® compiler v6.16 (ARM)
IAR C/C++ compiler v9.30.1 (IAR)

Supported kits (make variable 'TARGET')

PSoC™ 62S2 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062S2-43439) – Default value of TARGET
PSoC™ 6 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062-4343W)
PSoC™ 62S2 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062S2-43012)
PSoC™ 62S2 Evaluation Kit (CY8CEVAL-062S2-LAI-4373M2, CY8CEVAL-062S2-LAI-43439M2,CY8CEVAL-062S2-MUR-43439M2, CY8CEVAL-062S2-MUR-4373EM2, CY8CEVAL-062S2-MUR-4373M2, CY8CEVAL-062S2-CYW43022CUB)
PSoC™ 62S3 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062S3-4343W)
XMC7200 Evaluation Kit ( KIT_XMC72_EVK_MUR_43439M2)

Hardware setup

This example uses the board's default configuration. See the kit user guide to ensure that the board is configured correctly.

Software setup

See the ModusToolbox™ tools package installation guide for information about installing and configuring the tools package.

Install a terminal emulator if you don't have one. Instructions in this document use Tera Term.
This example uses a local-web-server to set up a local HTTP server, see Setting up an HTTP/HTTPS server using local-web-server for more details.
Install the Python interpreter and add it to the top of the system path in environmental variables. This code example is tested with Python v3.8.10.

Note: This code example currently does not work with the custom BSP name for the KIT_XMC72_EVK_MUR_43439M2 and CY8CPROTO-062S3-4343W kits. If you want to change the BSP name to a non-default value, ensure to update the custom BSP name in Makefile under the relevant section. The build fails, if you do not update the custom BSP name.

Structure and overview

This code example is a dual-core application, where the MCUboot-based bootloader application runs on the CM0P core and the OTA HTTPS application runs on the CM4/CM7 core. The OTA HTTPS application fetches the new image and places it in the secondary slot (flash), then the MCUboot takes care of updating the existing image with the new image. The mtb-example-mcuboot-basic code example is the MCUboot-based bootloader application used for this purpose.

The MCUboot-based bootloader application and this OTA HTTPS application should be built and programmed independently. They must be placed separately in the workspace as you would do for any other two independent applications. For this example, only the MCUboot-based bootloader application is required. The root directory of the MCUboot-based bootloader application is referred to as <MCUboot>/<bootloader_app> and the root directory of the OTA HTTPS application is referred to as <OTA_HTTPS> in this document. An example workspace is as follows:

<example-workspace>
   |
   |-<MCUboot>               # MCUboot-based bootloader and blinky applications directory
   |-<OTA_HTTPS>             # OTA HTTPS application directory
   |-<mtb_shared>            # Shared library for both the applications
   |

You must first build and program the MCUboot-based bootloader application into the CM0P core, and this should be done only once. The OTA HTTPS application can then be programmed into the CM4/CM7 core, and you need to only modify this application for all application purposes.

This README expects you to be familiar with MCUboot and its concepts. See MCUboot basics and MCUboot repository on GitHub for more information.

Using the code example

Create the project

The ModusToolbox™ tools package provides the Project Creator as both a GUI tool and a command line tool.

Use Project Creator GUI

Open the Project Creator GUI tool.

There are several ways to do this, including launching it from the dashboard or from inside the Eclipse IDE. For more details, see the Project Creator user guide (locally available at {ModusToolbox™ install directory}/tools_{version}/project-creator/docs/project-creator.pdf).
On the Choose Board Support Package (BSP) page, select a kit supported by this code example. See Supported kits.

Note: To use this code example for a kit not listed here, you may need to update the source files. If the kit does not have the required resources, the application may not work.
On the Select Application page:

a. Select the Applications(s) Root Path and the Target IDE.

Note: Depending on how you open the Project Creator tool, these fields may be pre-selected for you.

b. Select this code example from the list by enabling its check box.

Note: You can narrow the list of displayed examples by typing in the filter box.

c. (Optional) Change the suggested New Application Name and New BSP Name.

d. Click Create to complete the application creation process.

Use Project Creator CLI

The 'project-creator-cli' tool can be used to create applications from a CLI terminal or from within batch files or shell scripts. This tool is available in the {ModusToolbox™ install directory}/tools_{version}/project-creator/ directory.

Use a CLI terminal to invoke the 'project-creator-cli' tool. On Windows, use the command-line 'modus-shell' program provided in the ModusToolbox™ installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ tools. You can access it by typing "modus-shell" in the search box in the Windows menu. In Linux and macOS, you can use any terminal application.

The following example clones the "mtb-example-ota-https" application with the desired name "OTA_HTTPS" configured for the CY8CPROTO-062S2-43439 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CPROTO-062S2-43439 --app-id mtb-example-ota-https --user-app-name OTA_HTTPS --target-dir "C:/mtb_projects"

The 'project-creator-cli' tool has the following arguments:

Argument	Description	Required/optional
`--board-id`	Defined in the field of the BSP manifest	Required
`--app-id`	Defined in the field of the CE manifest	Required
`--target-dir`	Specify the directory in which the application is to be created if you prefer not to use the default current working directory	Optional
`--user-app-name`	Specify the name of the application if you prefer to have a name other than the example's default name	Optional

Note: The project-creator-cli tool uses the git clone and make getlibs commands to fetch the repository and import the required libraries. For details, see the "Project creator tools" section of the ModusToolbox™ tools package user guide (locally available at *{ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Open the project

After the project has been created, you can open it in your preferred development environment.

Eclipse IDE

If you opened the Project Creator tool from the included Eclipse IDE, the project will open in Eclipse automatically.

For more details, see the Eclipse IDE for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_ide_user_guide.pdf).

Visual Studio (VS) Code

Launch VS Code manually, and then open the generated {project-name}.code-workspace file located in the project directory.

For more details, see the Visual Studio Code for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_vscode_user_guide.pdf).

Keil µVision

Double-click the generated {project-name}.cprj file to launch the Keil µVision IDE.

For more details, see the Keil µVision for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_uvision_user_guide.pdf).

IAR Embedded Workbench

Open IAR Embedded Workbench manually, and create a new project. Then select the generated {project-name}.ipcf file located in the project directory.

For more details, see the IAR Embedded Workbench for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_iar_user_guide.pdf).

Command line

If you prefer to use the CLI, open the appropriate terminal, and navigate to the project directory. On Windows, use the command-line 'modus-shell' program; on Linux and macOS, you can use any terminal application. From there, you can run various make commands.

For more details, see the ModusToolbox™ tools package user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Testing flow of OTA HTTPS application

Follow the flow chart as shown in Figure 1.

Figure 1. Testing flow of OTA HTTPS application

Building and programming MCUboot

The mtb-example-mcuboot-basic code example bundles two applications: MCUboot-based bootloader application that runs on CM0P core, and blinky application that runs on CM4/CM7 core.

Import the mtb-example-mcuboot-basic code example per the instructions in the Using the code example section of its readme.

The MCUboot-based bootloader and OTA HTTPS applications must have the same understanding of the memory layout. The memory layout is defined through JSON files. The OTA HTTPS application provides a set of predefined JSON files that can be readily used. Both the MCUboot-based bootloader and OTA HTTPS applications must use the same JSON file.

The <OTA_HTTPS>/flashmap folder contains the pre-defined flashmap JSON files. The following files are supported by this example.

Table 1. Supported JSON files

Target	Supported JSON files
CY8CPROTO-062S2-43439 CY8CPROTO-062-4343W CY8CKIT-062S2-43012 CY8CEVAL-062S2-LAI-4373M2 CY8CEVAL-062S2-LAI-43439M2 CY8CEVAL-062S2-MUR-43439M2 CY8CEVAL-062S2-MUR-4373EM2 CY8CEVAL-062S2-MUR-4373M2 CY8CEVAL-062S2-CYW43022CUB	psoc62_2m_ext_overwrite_single.json psoc62_2m_ext_swap_single.json
CY8CPROTO-062S3-4343W	psoc62_512k_xip_swap_single.json
KIT_XMC72_EVK_MUR_43439M2	xmc7200_int_overwrite_single.json xmc7200_int_swap_single.json

Copy the required flashmap JSON file from the <OTA_HTTPS>/flashmap folder and paste it in the <MCUboot>/flashmap folder.

Modify the value of the FLASH_MAP variable in the <MCUboot>/user_config.mk file to the selected JSON file name from the previous step.
Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
Open a CLI terminal.

On Linux and macOS, you can use any terminal application. On Windows, open modus-shell app from the Start menu.
Navigate the terminal to the <mtb_shared>/mcuboot/<tag>/scripts folder.
Run the following commands to ensure that the required modules are installed.

Note: For Linux and macOS platforms, please use python3 instead of python in the below command.
```
python -m pip install -r requirements.txt
```
```
python -m pip install --upgrade cysecuretools==5.0.0
```
Note: cysecuretools is used for signing the image for XMC7000 MCUs.
Open a serial terminal emulator and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.
Build and program the bootloader application.
Using CLI

From the terminal, go to <MCUboot>/bootloader_app and execute the make program_proj command to build and program the MCUboot-based bootloader application using the default toolchain to the seleted target.
```
make program_proj
```
After programming, the MCUboot starts automatically. Confirm that the UART terminal displays a message as shown in Figure 2:

Figure 2. Booting with no bootable image

Setting up an HTTP/HTTPS server using local-web-server (based on node.js)

This code example uses a local server to demonstrate the OTA operation over HTTP/HTTPS. In this example, local-web-server is used. It is a lean, modular web server for rapid full-stack development.

Download and install node.js. Install with the default settings. Do not tick the checkbox to install optional tools for native modules.
Open a CLI terminal.

On Linux and macOS, you can use any terminal application. On Windows, open the modus-shell app from the Start menu.
Navigate to the <OTA_HTTPS>/scripts/ folder.
Execute the following command to generate self-signed SSL certificates and keys. On Linux and macOS, you can get your device-local IP address by running the ifconfig command on any terminal application. On Windows, run the ipconfig command on a command prompt.
```
sh generate_ssl_cert.sh <local-ip-address-of-your-pc>
```
Example:
```
sh generate_ssl_cert.sh 192.168.0.10
```
This step will generate the following files in the same <OTA_HTTPS>/scripts/ directory:
1. http_ca.crt – Root CA certificate
2. http_ca.key – Root CA private key
3. http_server.crt – Server certificate
4. http_server.key – Server private key
5. http_client.crt – Client certificate
6. http_client.key – Client private key
Execute the following command to install local-web-server.
```
npm install -g local-web-server
```

Start the local HTTP/HTTPS server:

Using the code example in TLS mode (default)

Execute the following command:

ws -p 4443 --hostname <local-ip-address-of-your-pc> --https --key http_server.key --cert http_server.crt --keep-alive-timeout <milli-seconds> -v

Example:

ws -p 4443 --hostname 192.168.0.10 --https --key http_server.key --cert http_server.crt --keep-alive-timeout 50000 -v

Figure 3. HTTPS server started in TLS Mode

Using the code example in non-TLS mode

Execute the following command:

ws -p 8080 --hostname <local-ip-address-of-your-pc> --keep-alive-timeout <milli-seconds> -v

Example:

ws -p 8080 --hostname 192.168.0.10 --keep-alive-timeout 50000 -v

Figure 4. HTTPS server started in non-TLS mode

Note: If you are running a local-web-server server on a device which is maintained by your organization or institution, the firewall settings may not permit you to host a file server on the local network. To verify whether the file server has been hosted properly from a device connected to the same local network, check the server link on a browser. Browse for http://<ip-address-noted-earlier>:<port-number-noted-earlier>; for example: http://192.168.0.10:8080. If the files in the <OTA_HTTPS>/scripts/ directory are listed on the browser page, you have a properly working file server. Do not proceed to the next section without getting the file server to work.

Operation

Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.

Modify the PLATFORM variable in the <OTA_HTTPS>/Makefile based on the target you have selected. Currently in the Makefile, a conditional if-else block is used to automatically select a value based on the target selected. You can remove it and directly assign a value as per Table 2.

Table 2: Target-specific platform values

Target	`PLATFORM` value
CY8CPROTO-062S2-43439 CY8CPROTO-062-4343W CY8CKIT-062S2-43012 CY8CEVAL-062S2-LAI-4373M2 CY8CEVAL-062S2-LAI-43439M2 CY8CEVAL-062S2-MUR-43439M2 CY8CEVAL-062S2-MUR-4373EM2 CY8CEVAL-062S2-MUR-4373M2 CY8CEVAL-062S2-CYW43022CUB	PSOC_062_2M
CY8CPROTO-062S3-4343W	PSOC_062_512K
KIT_XMC72_EVK_MUR_43439M2	XMC7200

Modify the OTA_FLASH_MAP variable in the <OTA_HTTPS>/Makefile to change the JSON file name to match the selection made while programming the MCUboot-based bootloader application. Currently in the Makefile, a conditional if-else block is used to automatically select a default flash map file based on the target selected. You can remove it and directly assign the path of the required flash map file to the OTA_FLASH_MAP variable.

The <OTA_HTTPS>/flashmap folder contains the pre-defined flashmap JSON files. The following files are supported by this example.

Table 3: Supported JSON files

Target	Supported JSON files
CY8CPROTO-062S2-43439 CY8CPROTO-062-4343W CY8CKIT-062S2-43012 CY8CEVAL-062S2-LAI-4373M2 CY8CEVAL-062S2-LAI-43439M2 CY8CEVAL-062S2-MUR-43439M2 CY8CEVAL-062S2-MUR-4373EM2 CY8CEVAL-062S2-MUR-4373M2 CY8CEVAL-062S2-CYW43022CUB	psoc62_2m_ext_overwrite_single.json psoc62_2m_ext_swap_single.json
CY8CPROTO-062S3-4343W	psoc62_512k_xip_swap_single.json
KIT_XMC72_EVK_MUR_43439M2	xmc7200_int_overwrite_single.json xmc7200_int_swap_single.json

Note: Both the MCUboot-based bootloader and OTA HTTPS applications must use the same JSON file.

Edit the <OTA_HTTPS>/configs/ota_app_config.h file to configure your OTA HTTPS application:
1. Modify the connection configuration such as WIFI_SSID, WIFI_PASSWORD, and WIFI_SECURITY macros to match the settings of your Wi-Fi network. Make sure that the device running the HTTP server and the kit are connected to the same network.
2. Modify the HTTP_SERVER address to match the IP address of your HTTP server.
3. Ensure the value of the HTTP_SERVER_PORT macro is 4443.
  
  Note: If the code example has been configured to work in non-TLS mode, set the value of HTTP_SERVER_PORT macro as 8080.
4. By default, this code example uses HTTPS (TLS) protocol. To use the example in HTTP (non-TLS) mode, modify ENABLE_TLS to false and skip the next step of adding the certificate.
5. Add the certificates and key:
  1. Open a CLI terminal.
    
    On Linux and macOS, you can use any terminal application. On Windows, open modus-shell app from the Start menu.
  2. Navigate the terminal to <OTA_HTTPS>/scripts/ directory.
  3. Run the format_cert_key.py Python script to generate the string format of the http_ca.crt file that can be added as a macro. Pass the name of the certificate with the extension as an argument to the Python script:
    
    Note: For Linux and macOS platforms, please use python3 instead of python in the below command.
```
python format_cert_key.py <one-or-more-file-name-of-certificate-or-key-with-extension>
```
    Example:
```
python format_cert_key.py http_ca.crt
```
  4. Copy the generated string and add it to the ROOT_CA_CERTIFICATE macro as per the sample shown.
    
    Note: The local-web-server does not authenticate a client through the certificate; this is the reason why the client certificate and client key are not added here. If you use some other server, which can do client-side authentication, add the http_client.crt and http_client.key files. Also, set the USING_CLIENT_CERTIFICATE and USING_CLIENT_KEY macros to value true.
Edit the job document (<OTA_HTTPS>/scripts/ota_update.json):
1. Modify the value of the variable Board to your selected TARGET in the following format.
```
if TARGET=APP_CY8CPROTO-062S2-43439, then Board:"APP_CY8CPROTO_062S2_43439"

if TARGET=APP_KIT_XMC72_EVK_MUR_43439M2, then Board:"APP_KIT_XMC72_EVK_MUR_43439M2"
```
  Example:
```
Board:"APP_CY8CPROTO_062S2_43439"
```
  Note: Please make sure to change the - to _ in the Board variable value while copying from the TARGET variable.
2. Modify the value of the Server to match the IP address of your HTTP server.
3. Ensure the value of the Port is 4443.
  
  Note: If the code example has been configured to work in non-TLS mode, set the value of Port as 8080.
4. Ensure the value of the Connection is HTTPS.
  
  Note: If the code example has been configured to work in non-TLS mode, set the value of Connection as HTTP.
Program the board using one of the following:
Using Eclipse IDE for ModusToolbox™
1. Select the application project in the Project Explorer.
2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).
In other IDEs

Follow the instructions in your preferred IDE.
Using CLI

From the terminal, execute the make program command to build and program the application using the default toolchain to the default target. The default toolchain is specified in the application's Makefile but you can override those values manually:
```
make program TOOLCHAIN=<toolchain>
```
Example:
```
make program TOOLCHAIN=GCC_ARM
```
After programming, MCUboot will validate the primary image. After successfully validating the primary image, MCUboot lets the CM4/CM7 core run the image from the primary slot. Observe that the user LED blinks at a one second interval. Observe the messages on the UART terminal and wait for the device to make the required connections. Once the HTTP client (device) is connected to the server, it will download the job document (ota_update.json) as shown in Figure 6.

Figure 5 shows the logs of HTTP server response for the job document request from the HTTP client.

Figure 5. Response for the job document request

Figure 6. Connection to the HTTP server
The job document (ota_update.json) placed in the <OTA_HTTPS>/scripts folder has value of Version as 1.0.0. The OTA update will not happen, because the OTA HTTPS application version and available update version are the same.
Modify the value of the BLINKY_DELAY_MS macro to (100) in the <OTA_HTTPS>/source/led_task.c file and change the application version in the <OTA_HTTPS>/Makefile by setting APP_VERSION_MINOR to 1.
Build the application (DO NOT program it to the kit). This new image will be uploaded to the HTTP server in the following steps to demonstrate the OTA update.
Using Eclipse IDE for ModusToolbox™
1. Select the application project in the Project Explorer.
2. In the Quick Panel, scroll down, and click Build <OTA_HTTPS> Application.
Using CLI
1. From the terminal, execute the make build command to build the application using the default toolchain to the default target. You can specify a target and toolchain manually:
```
make build TOOLCHAIN=<toolchain>
```
  Example:
```
make build TOOLCHAIN=GCC_ARM
```
After a successful build, copy the mtb-example-ota-https.bin file from <OTA_HTTPS>/build/<TARGET>/Debug and paste it to the <OTA_HTTPS>/scripts directory.
Edit the <OTA_HTTPS>/scripts/ota_update.json file to modify the value of Version to 1.1.0.
The OTA HTTPS application now finds and downloads the updated job document, and now the available update version is higher than the OTA HTTPS application version. So the OTA HTTPS application starts to download the new image as shown in Figure 8, and places it in the secondary slot. Once the download is completed, a soft reset is issued. Then the MCUboot starts the image upgrade process (swapping the images between the primary and secondary slots, after successfully validating the secondary image). It will take approximately 15 to 20 minutes.

Figure 7 shows the logs of HTTP server while uploading the new image.

Figure 7. Uploading the new image

Figure 8. Image download
After the image upgrade is successfully completed, MCUboot lets the CM4/CM7 core run the new image from the primary slot. Observe that the user LED is now blinking at a 100-millisecond interval and The UART terminal displays the message as shown in Figure 9.

Figure 9. Updated to new image
To test the revert feature of MCUboot, send a bad image as v1.2.0 OTA update. The bad image used in this example is an infinite loop. The watchdog timer will reset the bad image and upon reboot, MCUboot will revert the primary image back to v1.1.0, the good image. Edit <OTA_HTTPS>/Makefile and add TEST_REVERT to the Defines variable as shown:
```
DEFINES+=TEST_REVERT
```
Note: In an overwrite-based upgrade, the secondary image is simply copied to the primary slot after successful validation. There is no way to revert the upgrade if the secondary image is inoperable. TEST_REVERT feature is not applicable for overwrite-based upgrade.

See the MCUboot basics of the mtb-example-mcuboot-basic code example for more details about the overwrite-based and swap-based upgrades.
Edit the application version in the <OTA_HTTPS>/Makefile by setting APP_VERSION_MINOR to 2.
Build the application as per Step 10.
After a successful build, copy the mtb-example-ota-https.bin file from <OTA_HTTPS>/build/<TARGET>/Debug and paste it into the <OTA_HTTPS>/scripts directory.
Edit the <OTA_HTTPS>/scripts/ota_update.json file to modify the value of Version to 1.2.0.
The OTA HTTPS application will now find this new v1.2.0 image and update it. After the update, within a few seconds, the watchdog timer resets the devices. Upon reset, MCUboot reverts to the v1.1.0 good image. The UART terminal displays the message as shown in Figure 10.

Figure 10. Reverting to good image

Note: After completing the last step, the device will be running the v1.1.0 good image and the server will still have the v1.2.0 bad image. Because the version of the image on the server is greater than the version of the image on the device, the device will re-download the v1.2.0 bad image. This causes an infinite upgrade and reverts the cycle. To avoid this scenario, stop the HTTP/HTTPS server after you test the code example. In a production environment, the application is responsible for blacklisting bad image versions and to avoid upgrading to them in the future.

Debugging

You can debug the example to step through the code. In the IDE, use the <OTA_HTTPS> Debug (KitProg3_MiniProg4) configuration in Quick Panel. For more details, see the "Program and debug" section in the Eclipse IDE for ModusToolbox™ user guide.

Note: (Only while debugging) On the CM4 CPU, some code in main() may execute before the debugger halts at the beginning of main(). This means that some codes execute twice - once before the debugger stops execution, and again after the debugger resets the program counter to the beginning of main(). See KBA231071 to learn about this and for the workaround.

Design and implementation

Figure 11 shows the flow of the OTA update process using HTTPS. The application which needs OTA updates should run the OTA agent. The OTA agent spawns threads to receive OTA updates when available, without intervening with the application's core functionality.

The initial application resides in the primary slot of the flash. When the OTA agent receives an update, the new image is placed in the secondary slot of the flash. On the next reboot, MCUboot copies the image from the secondary slot into the primary slot, and then CM4 or CM7 will run the upgraded image from the primary slot.

Figure 11. Overview of OTA update using HTTPS

For more details on the features and configurations offered by the ota-update library, see its README.

Both MCUboot-based bootloader and user applications must have an identical understanding of the memory layout. Otherwise, the MCUboot may consider an authentic image as invalid.

For more details on the features and configurations of MCUboot-based bootloader, see the Design and implementation of MCUboot.

This example implements two RTOS tasks: OTA client and LED blinky. Both these tasks are independent and do not communicate with each other. The OTA client task initializes the dependent middleware and starts the OTA agent. The LED task blinks the user LED at a specified delay.

All the source files related to the two tasks are placed under the <OTA_HTTPS>/source folder:

Table 4: Source files related to OTA client and LED blinky

File	Description
ota_task.c	Contains the task and functions related to the OTA client.
ota_task.h	Contains the public interfaces for the OTA client task.
led_task.c	Contains the task and functions related to LED blinking.
led_task.h	Contains the public interfaces for the LED blink task.
main.c	Initializes the BSP and the retarget-io library, and creates the OTA client and LED blink tasks.
heap_usage	Contains the code for printing heap usage.

All the scripts and configurations needed for this example are placed under the <OTA_HTTPS>/scripts folder:

Table 5: Scripts and configuration files for OTA update over HTTPS

File	Description
generate_ssl_cert.sh	Shell script to generate the required self-signed CA, server, and client certificates
ota_update.json	OTA job document
format_cert_key.py	Python script to convert certificate/key to string format

The <OTA_HTTPS>/configs folder contains other configurations related to the OTA middleware, FreeRTOS, and MBEDTLS.

Table 6: Application configuration files

File	Description
ota_app_config.h	Contains the OTA and Wi-Fi configuration macros such as SSID, password, HTTP server details, certificates, and key.
cy_ota_config.h	Contains the OTA middleware level configuration macros.
mbedtls_user_config.h	Contains the ota_app_config.h configuration macros.
COMPONENT_CM7/FreeRTOSConfig.h	Contains the FreeRTOS configuration macros for XMC7000 family.
COMPONENT_CM4/FreeRTOSConfig.h	Contains the FreeRTOS configuration macros for PSoC6™ family.
COMPONENT_MCUBOOT/flash/cy_ota_flash.c	Contains OTA flash operation APIs.
COMPONENT_MCUBOOT/flash/COMPONENT_OTA_PSOC_062/flash_qspi.c	Contains QSPI flash related APIs.
COMPONENT_MCUBOOT/flash/COMPONENT_OTA_PSOC_062/flash_qspi.h	Contains the declaration of QSPI flash related APIs.

Security

The MCUboot-based bootloader application enables image authentication feature of MCUboot library. MCUboot verifies the signature of the image in the primary slot every time before booting. In addition, it verifies the signature of the image in the secondary slot before copying it to the primary slot. When these options are enabled, the public key (cypress-test-ec-p256.pub) is embedded within the MCUboot-based bootloader application. The OTA HTTPS application is signed using the private key (cypress-test-ec-p256.pem) during the post-build steps, the ota-bootloader-abstraction library is taken care the image signing for the OTA HTTPS application.

the MCUboot-based bootloader application includes a sample public key (cypress-test-ec-p256.pub) under the <MCUboot>/keys directory and the OTA HTTPS application includes a sample private key (cypress-test-ec-p256.pem) under the <mtb_shared>/ota-bootloader-abstraction/<tag>/scripts/mcuboot/keys directory. Both the <MCUboot>/keys and <mtb_shared>/ota-bootloader-abstraction/<tag>/scripts/mcuboot/keys directories must have the same pair of keys. Otherwise image (primary/secondary) validation fails, MCUboot-based bootloader application will prints a message "MCUBoot Bootloader found none of bootable images".

You must not use this key pair in your end product. See Generating a key pair for generating a new key pair. Once you generated the key pair, copy the keys to the both <MCUboot>/keys and <mtb_shared>/ota-bootloader-abstraction/<tag>/scripts/mcuboot/keys directories.

Note: See Security to learn more about the image authentication feature of MCUboot.

Resources and settings

Table 7. Application resources

Resource	Alias/object	Purpose
UART (HAL)	cy_retarget_io_uart_obj	UART HAL object used by Retarget-IO for the Debug UART port
GPIO (HAL)	CYBSP_USER_LED	User LED

Related resources

Resources	Links
Application notes	AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ AN215656 – PSoC™ 6 MCU: Dual-CPU system design AN234334 – Getting started with XMC7000 MCU on ModusToolbox™ AN234023 – Smart IO usage setup in XMC7000 family
Code examples	Using ModusToolbox™ on GitHub
Device documentation	PSoC™ 6 MCU datasheets PSoC™ 6 reference manuals XMC7000 MCU datasheets XMC7000 reference manuals
Development kits	Select your kits from the Evaluation board finder XMC™ evaluation boards
Libraries on GitHub	mtb-pdl-cat1 – PSoC™ 6 Peripheral Driver Library (PDL) mtb-hal-cat1 – Hardware Abstraction Layer (HAL) library
Middleware on GitHub	psoc6-middleware – Links to all PSoC™ 6 MCU middleware mcu-middleware – Links to all MCU middleware MCUboot – Open-source library enabling the development of secure bootloader applications for 32-bit MCUs retarget-io – Utility library to retarget STDIO messages to a UART port ota-update – OTA library and docs wifi-mw-core – Wi-Fi middleware core library and docs ota-bootloader-abstraction - OTA MCUboot-based bootloader abstraction http-client – HTTP client library and docs
Tools	ModusToolbox™ – ModusToolbox™ software is a collection of easy-to-use libraries and tools enabling rapid development with Infineon MCUs for applications ranging from wireless and cloud-connected systems, edge AI/ML, embedded sense and control, to wired USB connectivity using PSoC™ Industrial/IoT MCUs, AIROC™ Wi-Fi and Bluetooth® connectivity devices, XMC™ Industrial MCUs, and EZ-USB™/EZ-PD™ wired connectivity controllers. ModusToolbox™ incorporates a comprehensive set of BSPs, HAL, libraries, configuration tools, and provides support for industry-standard IDEs to fast-track your embedded application development.

Other resources

Infineon provides a wealth of data at www.infineon.com to help you select the right device, and quickly and effectively integrate it into your design.

For XMC™ MCU devices, see 32-bit XMC™ Industrial microcontroller based on Arm® Cortex®-M.

Document history

Document title: CE231585 – Over-the-air firmware update using HTTPS

Version	Description of change
1.0.0	New code example
1.1.0	Updated the configuration file to support MbedTLS v2.22.0
2.0.0	Update to: 1. Support anycloud-ota v4.X library. 2. Support swap upgrade with MCUboot. 3. Support local-web-server instead of mongoose
3.0.0	Update to support ModusToolbox™ software v2.4 and BSP v3.X Added support for CY8CEVAL-062S2-MUR-43439M2 and CY8CEVAL-062S2-LAI-4373M2 kits
4.0.0	Updated the example to use the new ota-update v1.0.0 library
5.0.0	Updated the example to use the ota-update v1.1.0 library Updated to support ModusToolbox™ software v3.0 Added support for CY8CPROTO-062S3-4343W kit
5.1.0	Added support for CY8CEVAL-062S2-LAI-43439M2
5.2.0	Added support for CY8CPROTO-062S2-43439
5.3.0	Updated to support ModusToolbox™ v3.1 and added support for CY8CEVAL-062S2-MUR-4373M2 and CY8CEVAL-062S2-MUR-4373EM2
5.4.0	Added support for CY8CEVAL-062S2-CYW43022CUB
5.5.0	Updated to support ModusToolbox™ v3.2
6.0.0	Updated to support OTA update middleware v4.0.0 Added support for KIT_XMC72_EVK_MUR_43439M2 kit.

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Name		Name	Last commit message	Last commit date
Latest commit History 13 Commits
configs		configs
deps		deps
flashmap		flashmap
images		images
scripts		scripts
source		source
templates		templates
.cyignore		.cyignore
.gitignore		.gitignore
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md

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Over-the-air firmware update using HTTPS

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Setting up an HTTP/HTTPS server using local-web-server (based on node.js)

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Over-the-air firmware update using HTTPS

Requirements

Supported toolchains (make variable 'TOOLCHAIN')

Supported kits (make variable 'TARGET')

Hardware setup

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Using the code example

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Open the project

Testing flow of OTA HTTPS application

Building and programming MCUboot

Setting up an HTTP/HTTPS server using local-web-server (based on node.js)

Operation

Debugging

Design and implementation

Security

Resources and settings

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