Connecting to Azure IoT services using Azure SDK for Embedded C

This code example demonstrates connecting to the Azure IoT services using the Azure Software Development Kit (SDK) for Embedded C and Infineon's Wi-Fi connectivity SDK. This code example demonstrates features such as Internet of Things (IoT) Hub, Cloud to device (C2D), Telemetry, Methods, Device Twin, Azure Device Provisioning Service (DPS), and Plug and Play (PnP).

In this example, the Azure C SDK port is used with the Mosquitto (MQTT) library to connect to the Azure cloud. The IoT device authentication mode can either be X509 certificate-based or shared access signature (SAS)-based. During startup, the application provides a menu displaying features of Azure IoT Hub service. Depending upon the use case selected, the message transmission takes place either from the cloud to the MCU device or vice versa.

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, 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
Other tools: Python v3.8.10 or later

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™ 64 "Secure Boot" Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-064B0S2-4343W) – Default value of TARGET
PSoC™ 6 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062-4343W)
PSoC™ 6 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062-WIFI-BT)
PSoC™ 62S2 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062S2-43012)
PSoC™ 62S2 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062S2-43439)
PSoC™ 62S1 Wi-Fi Bluetooth® Pioneer Kit (CYW9P62S1-43438EVB-01)
PSoC™ 62S1 Wi-Fi Bluetooth® Pioneer Kit (CYW9P62S1-43012EVB-01)
PSoC™ 62S2 Evaluation Kit (CY8CEVAL-062S2-LAI-4373M2, CY8CEVAL-062S2-MUR-43439M2, CY8CEVAL-062S2-LAI-43439M2, CY8CEVAL-062S2-MUR-4373EM2)

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.
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.
Open a CLI terminal and navigate to the scripts directory. Run the following command to ensure the required modules are installed ("Requirement already satisfied" is printed).
```
pip install -r requirements.txt
```

Note: The CySecureTools v4.1.0 or later will be used in this example, which will be downloaded as a part of pip install using "requirements.txt".

This example requires the setup of Azure IoT Hub on the Microsoft Azure portal. Additionally, the visual studio code and its Azure IoT tool extension need to be set up with the created Azure Hub.

Reference links:

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 "Azure IoT" application with the desired name "AzureIoT" configured for the CY8CKIT-064B0S2-4343W BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CKIT-064B0S2-4343W --app-id mtb-example-azure-iot --user-app-name AzureIoT --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).

Authentication credentials setup

This section contains the steps to setup the X509 or SAS credentials-based on the hardware for the Azure IoT Hub.

Credentials setup for non-secured platform

For SAS-based authentication, the token generation steps are mentioned in the Operation section.
For using X509-based certificate authentication, the steps are as follows:

X509 certificate-based authentication mode

Use the following steps to generate the device's X509 self-signed certificate and private key to setup the X509 authentication-based device on Azure IoT Hub.

In the < application > directory, create a certificates directory.

Run the following command in the modus-shell in the certificates folder to generate the device private key.

openssl req -newkey rsa:2048 -nodes -keyout dev_priv_key.pem

To run this command, enter the additional information, as shown in the following example. The Common Name can be the user's choice but must match the registration ID on the Azure DPS portal's enrollment or the device ID on the Azure IoT Hub portal is created in the following steps:

The A challenge password and An optional company name fields are left blank.

Country Name (2 letter code) [XX]:US
State or Province Name (full name) []:CA
Locality Name (e.g, city) [Default City]:SJ
Organization Name (e.g, company) [Default Company Ltd]:IFX
Organizational Unit Name (e.g, section) []:INFINEON
Common Name (e.g, your name or your server's hostname) []:azure_dps_dev_test1
Email Address []:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Copy the x509_config.cfg file from the scripts folder to certificates folder.
Run the following command in the modus-shell in the certificates directory to generate the X.509 certificate.

Note: The value of the common name field in the following command - CN can be the user's choice but must match the registration ID on the Azure DPS portal's enrollment or the device ID on the Azure IoT Hub portal is created as mentioned in the following steps:
```
openssl req -new -days 1024 -nodes -x509 -key dev_priv_key.pem -out device_cert.pem -extensions client_auth -config x509_config.cfg -subj "/CN=azure_dps_dev_test1"
```
Run the following command in the modus-shell in the certificates directory to get the SHA thumbprint of the device certificate created in Step 4. Copy the fingerprint generated in the following command.
```
openssl x509 -noout -fingerprint -in device_cert.pem | sed 's/://g'| sed 's/$SHA1 Fingerprint=$//g'
```
Example of a fingerprint from the previous command:
```
902E7A49F252A49D0AB30AB1D2FBEAE702495F2F
```
For Azure DPS flow - To create Individual Enrollment in the Azure DPS portal, see X509 DPS device enrollment. Select the X509 mode of authentication and upload the device_cert.pem in both Primary Certificate and Secondary Certificate fields and then save. The registration ID of the created enrollment appears the same as the CN used in Step 5.

For without Azure DPS flow - In the Azure portal, see Azure device setup and create the Azure IoT device using X509 self-signed option. Paste the same fingerprint copied in Step 6 in both "primary" and "secondary" thumbprints. The device name should be same as Common Name used in Step 1 of this section where the root certificate is created.
Download Baltimore CyberTrust Root certificate and place it in the certificates folder then run the below command to convert the certificate from .crt to .pem. The out parameter must be azure_rootCA.pem.
```
openssl x509 -inform der -in BaltimoreCyberTrustRoot.crt -out azure_rootCA.pem
```
Note: If the Azure IoT Device is configured to use the DigiCert Global G2 Root certificate, use the same here.
In source/mqtt_main.h, set azure_root_ca_certificate to the azure_RootCA.pem and set device certificate and device key. The pem format of the certificates and keys needs to be used in the file. Use scripts/format_X509_cert_key.py to generate the formatted pem to be used in source/mqtt_main.h. Copy and paste this script in certificates folder and use it as follows:
```
python format_X509_cert_key.py azure_rootCA.pem device_cert.pem dev_priv_key.pem
```
Note: Refer to the Baltimore CyberTrust Root certificate for the latest version of the certificate used for Azure IoT.

Credentials setup for a secured platform (CY8CKIT-064B0S2-4343W)

CY8CKIT-064B0S2-4343W requires provisioning of keys and policies into the hardware, following sections describe the steps for the same. These secure keys and policies are used during the secure boot flow. For more information on secure boot sdk refer to the PSoC™ 64 MCU "Secure Boot" user guide.

Shared access signature (SAS)- based authentication mode

This section describes the provisioning steps for this example and the setup of SAS tokens into the secure hardware, these will be used for a secure socket connection with the Azure cloud.

Before generating the SAS tokens the kit needs to be provisioned with keys and policies using the following steps:

Note: The KitProg3 must be in DAPLink mode for performing this section. Press the 'Mode' button on the kit until the Status LED blinks fast. Also, ensure the J26 jumper is open.

In modus-shell navigate to the folder < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W. The imports folder will be created during the library manager update of the Trusted Firmware-M asset, library manager update takes place as mentioned in Using the code example section.

Run the following command.

cysecuretools --target CY8CKIT-064B0S2-4343W init

Run the following commands in the modus-shell from < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W directory. Select n if prompted for overwriting keys folder.

Note: If the kit is provisioned prior to this step, skip to the next step.
```
cysecuretools -t CY8CKIT-064B0S2-4343W -p policy/policy_multi_CM0_CM4_tfm_dev_certs.json create-keys
cysecuretools -t CY8CKIT-064B0S2-4343W -p policy/policy_multi_CM0_CM4_tfm_dev_certs.json provision-device
```
Create a folder called certificates and then navigate into certificates folder in modus-shell.

Run the following commands in the modus-shell to generate the root certificate and root key.

openssl genrsa -out rootCA.key 2048

openssl req -x509 -new -nodes -key rootCA.key -sha256 -days 1024 -out rootCA.pem

When you run this command, you need to enter additional information, as shown below. Leave the Common Name and Email Address fields empty.

Country Name (2 letter code) [XX]:US
State or Province Name (full name) []:CA
Locality Name (e.g, city) [Default City]:SJ
Organization Name (e.g, company) [Default Company Ltd]:IFX
Organizational Unit Name (e.g, section) []:INFINEON
Common Name (e.g, your name or your server's hostname) []:
Email Address []:

Download Baltimore CyberTrust Root certificate and place it in the certificates folder then run the below command to convert the certificate from .crt to .pem. The out parameter must be azure_rootCA.pem.
```
openssl x509 -inform der -in BaltimoreCyberTrustRoot.crt -out azure_rootCA.pem
```
Note: If the Azure IoT device is configured to use the DigiCert Global G2 root certificate, use the same here.
Inside the < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W/policy folder, edit the "provisioning" section of the policy_multi_CM0_CM4_tfm_dev_certs.json policy as shown below and then save and close this policy file.
```
"provisioning":
{
   "packet_dir": "../packets",
   "chain_of_trust": ["../certificates/device_cert.pem", "../certificates/azure_rootCA.pem"]
},
```
Copy the script reprov_helper.py from the folder < application >/imports/trusted-firmware-m/security to the folder < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W.
This step will generate device certificate and provision the device certificate & azure_RootCA into the hardware.

Run the following command in the modus-shell in the < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W directory to create the device certificate, keys, and provision them in the hardware. When prompted, enter a device serial number of your choice, 1234. Select N when asked to create new keys and allow for reprovisioning by selecting y.
```
python reprov_helper.py -p policy/policy_multi_CM0_CM4_tfm_dev_certs.json -d cy8ckit-064b0s2-4343w
```
On the kit, press the 'Mode' button again until the KitProg3 status LED stops blinking and place the J26 jumper back.

For SAS mode, a valid device ID and corresponding SAS token needs to be stored in the secured element through the following steps.

Create an Azure IoT Device or Individual enrollment as mentioned in Step 3 of the [Operation] (#operation) section.
For Azure DPS flow - Update the file source/mqtt_iot_sas_token_provision.c as follows -
- Update the registration ID in the AZURE_CLIENT_DEVICE_ID macro.
- Update the SAS token in the AZURE_CLIENT_SAS_TOKEN macro.
For without Azure DPS flow - Update the file source/mqtt_iot_sas_token_provision.c as follows -
- Update the device ID in the AZURE_CLIENT_DEVICE_ID macro.
- Update the SAS token in the AZURE_CLIENT_SAS_TOKEN macro.
Run the application source/mqtt_iot_sas_token_provision.c to store the device ID and SAS token in the secured element. To build the source/mqtt_iot_sas_token_provision.c application;

Uncomment the following line in the Makefile to disable the build of source/main.c.

#CY_IGNORE += ./source/main.c

Comment the following line to enable the build of source/mqtt_iot_sas_token_provision.c.

CY_IGNORE += ./source/mqtt_iot_sas_token_provision.c

Perform clean, build, and finally program the application in a similar way as in Using the code example section. On successful provisioning, a message appears as shown in Figure 1.

Figure 1: SAS token provision success

After successful provisioning of the SAS token into the hardware, enable source/main.c and disable source/mqtt_iot_sas_token_provision.c by editing the lines in the Makefile as shown below.
```
#CY_IGNORE += ./source/main.c
CY_IGNORE += ./source/mqtt_iot_sas_token_provision.c
```
Note: For SAS-based authentication mode, the application should pass azure_root_ca_certificate, azure_client_cert, and azure_client_key values as NULL in source/mqtt_main.h.

X509 certificate - based authentication mode

This section describes the provisioning steps for this example and the setup of X.509 certificates into the secure hardware, which will be used for secure socket connection with the Azure cloud.

Note: The KitProg3 must be in DAPLink mode for performing this section. Press the 'Mode' button on the kit until the status LED blinks fast. Ensure that the J26 jumper is open.

In modus-shell navigate to the folder < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W. The imports folder will be created during the library manager update of the Trusted Firmware-M asset, library manager update takes place as mentioned in Using the code example section.

Run the following command.

cysecuretools --target CY8CKIT-064B0S2-4343W init

Run the following commands in the modus-shell from < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W directory. Select n if prompted for overwriting keys folder.

Note: If the kit is already provisioned, skip to the next step.
```
cysecuretools -t CY8CKIT-064B0S2-4343W -p policy/policy_multi_CM0_CM4_tfm_dev_certs.json create-keys
cysecuretools -t CY8CKIT-064B0S2-4343W -p policy/policy_multi_CM0_CM4_tfm_dev_certs.json provision-device
```
Create a folder called certificates and then navigate into certificates folder in modus-shell.

Run the following commands in the modus-shell to generate the root certificate and root key:

openssl genrsa -out rootCA.key 2048

openssl req -x509 -new -nodes -key rootCA.key -sha256 -days 1024 -out rootCA.pem

To run this command, enter additional information, as shown below. Leave the Common Name and Email Address fields empty.

Country Name (2 letter code) [XX]:US
State or Province Name (full name) []:CA
Locality Name (e.g, city) [Default City]:SJ
Organization Name (e.g, company) [Default Company Ltd]:IFX
Organizational Unit Name (e.g, section) []:INFINEON
Common Name (e.g, your name or your server's hostname) []:
Email Address []:

Download Baltimore CyberTrust Root certificate and place it in the certificates folder then run the below command to convert the certificate from .crt to .pem. The out parameter must be azure_rootCA.pem.
```
openssl x509 -inform der -in BaltimoreCyberTrustRoot.crt -out azure_rootCA.pem
```
Inside the < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W/policy folder, edit the "provisioning" section of the policy_multi_CM0_CM4_tfm_dev_certs.json policy as shown below and then save and close this policy file.
```
"provisioning":
{
   "packet_dir": "../packets",
   "chain_of_trust": ["../certificates/device_cert.pem", "../certificates/azure_rootCA.pem"]
},
```
Copy the script reprov_helper.py from the folder < application >/imports/trusted-firmware-m/security to the folder < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W.
This step will generate device certificate and provision the device certificate & azure_RootCA into the hardware.

Run the following command in the modus-shell in the < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W directory to create the device certificate and keys and then provision them in the hardware. When prompted enter a device serial number of your choice, 1234. Select N when asked to create new keys and allow for reprovisioning by selecting y.
```
python reprov_helper.py -p policy/policy_multi_CM0_CM4_tfm_dev_certs.json -d cy8ckit-064b0s2-4343w
```
On the kit, press the 'Mode' button again until the KitProg3 status LED stops blinking and place the J26 jumper back.
Run the following command in the modus-shell in the < application >/imports/trusted-firmware-m/security/COMPONENT_CY8CKIT-064B0S2-4343W/certificates directory to get the SHA thumbprint of the device certificate created in Step 10. Copy the fingerprint generated in the below command.

Example for a fingerprint:
```
openssl x509 -noout -fingerprint -in device_cert.pem | sed 's/://g'| sed 's/$SHA1 Fingerprint=$//g'
```
```
902E7A49F252A49D0AB30AB1D2FBEAE702495F2F
```
The Subject CN from the device certificate might be used in further steps. Use the below command on the generated device certificate to note the same.
```
openssl x509 -text -fingerprint -in device_cert.pem
```
A sample CN is shown in Figure 2.

Figure 2: Example subject common name
For Azure DPS flow - Create an Individual Enrollment in the Azure DPS portal by referring to X509 DPS device enrollment. Select the X509 mode of authentication and upload the device_cert.pem in both primary and secondary certificate fields and then save. The registration ID of the created enrollment will appear the same as the Subject CN as noted in the previous steps.

For without Azure DPS flow - In the Azure portal, see Azure device setup and create the Azure IoT device using X509 self-signed option. Paste the same fingerprint copied in the previous step in both primary and secondary thumbprints. The device name should be the same as the Subject CN as noted in the previous steps.

Note: Do not pass any certificates or keys from the application. While establishing a connection with the Azure broker, certificates and keys stored in the secured memory are used.

Note: See Baltimore CyberTrust Root certificate for the latest version of the certificate used for Azure IoT.

Operation

Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
Select from either of the following methods for authentication of the Azure IoT device with the Azure Hub.
Shared access signature (SAS)-based authentication mode
1. Set the SAS_TOKEN_AUTH macro to 1 in source/azure_common.h.
2. Update the files as follows:
  Non-secure hardware
  
  For non-secure hardware platforms like CY8CPROTO-062-4343W, the SAS token can be used in the following ways. Select from either of the following methods as per the use case.
  Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of Azure Device Provisioning Service menu option of this ModusToolbox™ application. Upon completing the following steps, the status of the provisioning is shown in Figure 8.
  
  Create a DPS and an Individual Enrollment by referring to the Quick DPS setup and SAS DPS device enrollment. Do not specify the device ID while doing the same as the registration ID will be used as the device ID in the further steps.
  
  Update valid Scope ID, Registration ID, and Provisioning SAS Key (Primary Key) values in scripts/dps_sas_token_generation.py. Run the script after updating it, note the generated SAS token.
  
  Note: The value of the Scope ID can be noted from the created Azure DPS portal. In addition, the Registration ID, and Provisioning SAS Key can be noted from the created Individual Enrollment portal.
  
  In source/azure_common.h, set the SAS_TOKEN_LOCATION_FLASH macro as true.
  
  In source/mqtt_main.h update the following macros:
  
  Update the above generated SAS token in IOT_AZURE_PASSWORD
  
  Update the DPS registration ID in IOT_AZURE_DPS_REGISTRATION_ID
  
  Update the ID scope value in IOT_AZURE_ID_SCOPE
  OR
  Without Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of the Azure Device App (C2D, Telemetry, Methods, Device Twin) and PnP (Plug and Play) menu options of this ModusToolbox™ application.
  
  Create a SAS authentication based device on the Azure IoT Hub by referring to Azure device setup.
  
  Generate a SAS token for the device using the following instructions as mentioned in SAS token generation. The VS Code's Get device info can be used for acquiring device information like the host name and device ID.
  
  In source/azure_common.h, set the SAS_TOKEN_LOCATION_FLASH macro as true.
  
  In source/mqtt_main.h update the following macros:
  
  Update the device ID in MQTT_CLIENT_IDENTIFIER_AZURE_SAS
  
  Update host name/hub name of the created IoT Hub in IOT_DEMO_SERVER_AZURE
  
  Update device ID in IOT_AZURE_USERNAME
  
  Update the generated SAS token in IOT_AZURE_PASSWORD
  Secure hardware
  
  For secure hardware platforms like CY8CKIT-064B0S2-4343W, the SAS token can be used in the following ways. Select from either of the following methods as per the use case.
  Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of Azure Device Provisioning Service menu option of this ModusToolbox™ application. Upon completing the following steps, the status of the provisioning is shown in Figure 8.
  
  Create a DPS and an Individual Enrollment by referring to the Quick DPS setup and SAS DPS device enrollment. Do not specify the device ID while doing the same as the registration ID will be used as the device ID in the further steps.
  
  Update valid Scope ID, Registration ID, and Provisioning SAS Key ( Primary Key ) values in scripts/dps_sas_token_generation.py. Run the script after updating it, note the generated SAS token.
  
  Note: The value of the Scope ID can be noted from the created Azure DPS portal. In addition, the Registration ID, and Provisioning SAS Key can be noted from the created Individual Enrollment portal.
  
  Provision the registration ID and generated SAS token by following the steps in Authentication credentials setup for the secure hardware.
  
  In source/azure_common.h, set the SAS_TOKEN_LOCATION_FLASH macro as false to enable reading of the device ID and SAS token from the secured element.
  
  In source/mqtt_main.h, update the following macros:
  
  Update the DPS registration ID in the IOT_AZURE_DPS_REGISTRATION_ID macro
  
  Update the ID scope value in the IOT_AZURE_ID_SCOPE macro
  OR
  Without Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of the Azure Device App (C2D, Telemetry, Methods, Device Twin) and PnP (Plug and Play) menu options of this ModusToolbox™ application.
  
  Create a SAS authentication based device on Azure IoT Hub by referring to Azure device setup.
  
  Generate a SAS token for the device by following the instructions in SAS token generation. The VS Code's Get device info can be used for acquiring device information like the host name and the device ID.
  
  In source/azure_common.h, set the SAS_TOKEN_LOCATION_FLASH macro as false to enable reading of the device ID and SAS token from the secured element.
  
  In source/mqtt_main.h, update the host name/hub name of the created IoT Hub in IOT_DEMO_SERVER_AZURE.
  
  Provision the device ID and the SAS token using the steps in Authentication credentials setup for secure hardware.
X509 certificate-based authentication mode
1. Set the SAS_TOKEN_AUTH macro to 0 and SAS_TOKEN_LOCATION_FLASH to false in source/azure_common.h.
2. Update the files as follows:
  Non-secure hardware
  Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of Azure Device Provisioning Service menu option of this ModusToolbox™ application. Upon completing the following steps, the status of the provisioning is shown in Figure 8.
  
  Create a DPS by referring to the Quick DPS setup.
  
  Refer to Authentication credentials setup for creating X.509 certificates and Individual Enrollment for Azure DPS.
  
  In source/mqtt_main.h update the following macros:
  
  Update the DPS registration ID in the MQTT_CLIENT_IDENTIFIER_AZURE_CERT macro
  
  Update host name/hub name (if known beforehand) on which the device will be registered in macro IOT_DEMO_SERVER_AZURE
  
  Note: After successful run of the DPS feature, the terminal logs will mention the host name/hub name on which the device will be registered, the same can also be updated in the macro and the kit reprogrammed with the same.
  
  Update the DPS registration ID in the IOT_AZURE_USERNAME macro
  
  Update the DPS registration ID in the IOT_AZURE_DPS_REGISTRATION_ID macro
  
  Update the ID scope value in the IOT_AZURE_ID_SCOPE macro
  
  Update the pem format value of certificates and keys in the azure_root_ca_certificate, azure_client_cert, and azure_client_key as mentioned in the Authentication credentials setup section for non-secure kit.
  
  Note: The value of the Scope ID can be noted from the created Azure DPS portal. In addition, the Registration ID, and Provisioning SAS Key can be noted from the created Individual Enrollment portal.
  OR
  Without Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of the Azure Device App (C2D, Telemetry, Methods, Device Twin) and PnP (Plug and Play) menu options of this ModusToolbox™ application. Upon completing the following steps, the status of the provisioning is as shown in Figure 8.
  
  Create an X509-based device, it's a certificate and private key for Azure IoT Hub by referring to Authentication credentials setup.
  
  In source/mqtt_main.h update the following macros:
  
  Update the device ID in the MQTT_CLIENT_IDENTIFIER_AZURE_CERT macro
  
  Update host name/hub name on which the device will be registered in macro IOT_DEMO_SERVER_AZURE
  
  Update the device ID in the IOT_AZURE_USERNAME macro
  
  Update the pem format value of certificates and keys in the azure_root_ca_certificate, azure_client_cert, and azure_client_key as mentioned in the Authentication credentials setup section for a non-secure kit.
  Secure hardware
  Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of Azure Device Provisioning Service menu option of this ModusToolbox™ application. Upon completing the following steps, the status of the provisioning is shown in Figure 8.
  
  Create a DPS by referring to the Quick DPS setup.
  
  See Authentication credentials setup for creating X.509 certificates and Individual Enrollment for Azure DPS. Certificates will be read from the secured memory during a TLS connection with Azure.
  
  In source/mqtt_main.h, update the following macros:
  
  Update the DPS registration ID in the MQTT_CLIENT_IDENTIFIER_AZURE_CERT macro
  
  Update host name/hub name (if known beforehand) on which the device will be registered in macro IOT_DEMO_SERVER_AZURE
  
  Note: After successful run of the DPS feature, the terminal logs will mention the host name/hub name on which the device will be registered, the same can also be updated in the macro and the kit reprogrammed with the same.
  
  Update the DPS registration ID in the IOT_AZURE_USERNAME macro
  
  Update the DPS registration ID in the IOT_AZURE_DPS_REGISTRATION_ID macro
  
  Update the ID scope value in the IOT_AZURE_ID_SCOPE macro
  
  Note: The value of the Scope ID can be noted from the created Azure DPS portal. In addition, the Registration ID, and Provisioning SAS Key can be noted from the created Individual Enrollment portal.
  
  In CY8CKIT-064B0S2-4343W kit example, FreeRTOS PSA PKCS11 implementation supports only SHA-256 hashing algorithm. So the application should choose the cipher suite list compatible with the SHA-256. To choose the cipher suite list, the application needs to add required cipher suites to the MBEDTLS_SSL_CIPHERSUITES macro in configs/mbedtls_user_config.h file. The sample configs/mbedtls_user_config.h file includes MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 and MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 cipher suites to communicate with the Azure broker.
  
  #define MBEDTLS_SSL_CIPHERSUITES MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,\ MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
  
  Note: See the list of supported cipher suites Azure Hub and Azure DPS before adding cipher suites to the MBEDTLS_SSL_CIPHERSUITES.
  OR
  Without Azure Device Provisioning Service (DPS)
  
  The following steps are used to generate the output of the Azure Device App (C2D, Telemetry, Methods, Device Twin) and PnP (Plug and Play) menu options of this ModusToolbox™ application. Upon completing the following steps, the status of the provisioning is shown in Figure 8.
  
  Create an X509-based device, it's a certificate and private key for the Azure IoT Hub by referring to Authentication credentials setup.
  
  In source/mqtt_main.h update the following macros:
  
  Update the device ID in the MQTT_CLIENT_IDENTIFIER_AZURE_CERT macro
  
  Update host name/hub name of the created IoT Hub in the IOT_DEMO_SERVER_AZURE macro
  
  Update the device ID in the IOT_AZURE_USERNAME macro
  
  The certificates and keys must be generated and provisioned as mentioned in the Authentication credentials setup section for the secure kit. Certificates and keys will be read from the secured memory during a TLS connection.
  
  In CY8CKIT-064B0S2-4343W kit example, FreeRTOS PSA PKCS11 implementation supports only SHA-256 hashing algorithm. So the application should choose the cipher suite list compatible with the SHA-256. To choose the cipher suite list, the application needs to add required cipher suites to the MBEDTLS_SSL_CIPHERSUITES macro in configs/mbedtls_user_config.h file. The sample configs/mbedtls_user_config.h file includes MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 and MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 cipher suites to communicate with the Azure broker.
  
  #define MBEDTLS_SSL_CIPHERSUITES MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,\ MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
  
  Note: See the list of supported cipher suites Azure Hub and Azure DPS before adding cipher suites to the MBEDTLS_SSL_CIPHERSUITES.
Update the Wi-Fi details WIFI_SSID and WIFI_PASSWORD in the source/mqtt_main.h file.
Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.
Program the board using one of the following:
Using Eclipse IDE
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 this value manually:
```
make program TOOLCHAIN=<toolchain>
```
Example:
```
make program TOOLCHAIN=GCC_ARM
```
The application presents a menu at the start, select the Azure IoT feature to be demonstrated. The Azure Device Provisioning demo registers the device on the Azure Hub. The Azure Device App demonstrates four features of the IoT Hub - Cloud to Device, Telemetry, Methods, and Device Twin. The other demo is for Plug and Play.

Once the demo is completed, the application disconnects from the Azure MQTT broker and Wi-Fi. To run other features, press the reset button and re-run the application.

Figure 3: Azure IoT features menu

Provisioning (DPS)

This application registers a device with the Azure IoT Device Provisioning Service. It will wait to receive the registration status and print the provisioning information. Upon success, device ID and the Hub name/Host Name on which the device is provisioned is displayed in the logs as marked in Figure 4. If the network disconnects, the application will exit.

Figure 4: Provisioning status message

Note: (Optional) For testing the Azure Hub features in the Azure Device App (C2D, Telemetry, Methods, Device Twin) and PnP (Plug and Play) menu options on the newly registered device follow the steps mentioned in Azure DPS Hub demo combination.

Cloud-to-device (C2D) messaging

The Azure Device App receives the incoming C2D messages sent from the Azure IoT Hub to the device.

To send a C2D message, select your device's Message to Device tab in the Azure portal in the IoT Hub. Enter a message in the Message Body and click Send Message.

Figure 5 is an example message from the cloud printed on the terminal.

Figure 5: C2D message

Telemetry

The Azure Device App sends 100 telemetry messages to the Azure IoT Hub. If the network disconnects, the application will exit. The device metrics can be checked on the Azure Hub for analysis of Telemetry, Metrics -> Add metric -> select "Telemetry messages send attempts".

Figure 6: Telemetry message

Methods

The Azure Device App receives incoming method commands invoked from the Azure IoT Hub to the device. It receives all method commands sent from the service. If the network disconnects while waiting for a message, the application will exit.

To send a method command, select your device's Direct Method tab in the Azure portal in the IoT Hub. Enter a method named ping in the Method Name field and click Invoke Method, which if successful will return the following JSON payload visible in the Result section of the Direct Method tab in the Azure portal.

{"response": "pong"}

No other method commands are supported. If any other methods are attempted to be invoked, the log will report that the method is not found.

Figure 7: Method response message

Device twin

The Azure Device App uses the Azure IoT Hub to get the device twin document, send a reported property message, and receive up to five desired property messages. When the desired property message is received, the application will update the twin property locally and send a reported property message back to the service. If the network disconnects while waiting for a message from the Azure IoT Hub, the application will exit.

A property named Test_count is supported for this application. To send a device twin desired property message, select the device's Device Twin tab in the Azure portal in the IoT Hub. Add the Test_count property along with the corresponding value to the desired section of the JSON, an example is shown below. Click Save to update the twin document and send the twin message from the cloud to the device.
```
"properties": {
     "desired": {
         "Test_count": 141,
          "$metadata": {
             "$lastUpdated": "2021-12-19T17:45:17.0942196Z"
         },
         "$version": 1
     },
```
Figure 8: Twin message

The application would report back the property Test_count to the Azure server. Upon selecting the Refresh button on the Device Twin portal, the updated Test_count can be seen in the reported section.

Plug and play (PnP)

The application connects an IoT Plug and Play enabled device with the Digital Twin Model ID (DTMI). The application waits for a message and will exit if the network disconnects.

To interact with the application, use the Azure IoT Explorer or use the Azure portal directly. The capabilities are Device twin, Direct method (Command), and Telemetry.
- Device Twin
  
  Two device twin properties are supported in this application:
  1. The desired property is named targetTemperature with a double value for the desired temperature.
  2. A reported property named maxTempSinceLastReboot with a double value for the highest temperature reached since device boot.
  To send a device twin desired property message, select your device's Device Twin tab in the Azure portal. Add the targetTemperature property along with a corresponding value to the desired section of the JSON object, as shown below. Select Save to update the twin document and send the twin message to the device.
```
"properties": {
   "desired": {
         "targetTemperature": 68.5,
         "$metadata": {
            "$lastUpdated": "2021-12-19T17:45:17.0942196Z"
         },
         "$version": 1
   },
```
  When the desired property message is received, the application will update the twin property locally and send a reported property of the same name back to the service. This message will include a set of "ack" values: ac for the HTTP-like ack code, av for the ack version of the property, and an optional ad for an ack description.
  
  Upon selecting the Refresh button on the Device Twin portal, the updated properties can be seen in the reported section as shown below:
```
{
   "properties":
   {
      "reported":
      {
         "targetTemperature":
         {
            "value": 68.5,
            "ac": 200,
            "av": 14,
            "ad": "success"
         },
         "maxTempSinceLastReboot": 74.3,
         ...
      }
   }
}
```
- Direct method (command)
  
  One device command is supported in this application: getMaxMinReport.
  
  If any other commands are attempted to be invoked, the log will report that the command is not found. To invoke a command, select your device's Direct Method tab in the Azure portal. Enter the command name getMaxMinReport in the Method Name field along with a payload using an ISO 8061 time format and select Invoke method. A sample payload is as follows:
  
  "2020-08-18T17:09:29-0700"
  
  The command will send back to the service a response containing the following JSON payload with the updated values in each field. It is visible in the Result section of the Direct Method tab in the Azure portal. An example response is shown below:
  
  Note: The system time at the time of sending the response will be reflected in endTime.
```
   {"status":400,"payload":{"maxTemp":68.5,"minTemp":22,"avgTemp":45.25,"startTime":"2020-08-18T17:09:29-0700","endTime":"1970-01-01T00:00:31+0000"}}
```
- Telemetry
  
  The device sends a JSON message with the field name temperature and the double value of the current temperature as telemetry data using the above two methods - Twin and Direct method.

Debugging

You can debug the example to step through the code.

In Eclipse IDE

Use the <Application Name> Debug (KitProg3_MiniProg4) configuration in the Quick Panel. For 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 code executes 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.

In other IDEs

Follow the instructions in your preferred IDE.

Design and implementation

This example implements three RTOS tasks to demonstrate Azure IoT Hub features: Cloud to Device (C2D), Telemetry, methods, Device Twin, Azure Device Provisioning (DPS), and plug and play (PnP). The main function initializes the BSP and the retarget-io library and calls the Menu function which presents the list of Azure features to the user. Upon selection of a feature, a task is created for running the feature. Every feature task requires valid certificates or tokens that need to be passed either from the flash or secured hardware. The application uses the MQTT client library to connect to the Azure IoT Hub. After the validation of IoT device credentials, the data exchange can then take place between the Hub and the device.

SAS Authentication

SAS tokens are generated using symmetric keys provided during device enrollment. The device then uses this key to generate SAS tokens. These SAS tokens have a hashed signature, which is used to verify the authenticity of these tokens. Once the device is authenticated, these SAS tokens are used to connect to Azure IoT Hub and send messages.
X.509 authentication

X.509 certificate PKI is used to authenticate devices to the IoT Hub and secure the IoT Hub endpoints. The process begins with registering and uploading the X.509 certificates to an IoT Hub which will be used for authentication of IoT devices to the IoT Hub whenever they connect. This authentication process saves you from generating private secure keys for every IoT device. With the X.509 CA feature, you need to register the certificate just once, and then use it to connect and authenticate as many devices as we want.
Device Provisioning Service (DPS)

It is a helper service for IoT Hub that enables zero-touch, just-in-time provisioning to the right IoT Hub without requiring human intervention, allowing customers to provision millions of devices in a secure and scalable manner.
Scenarios where DPS is best choice
- Load-balancing devices across multiple hubs
- Connecting a device to the IoT Hub with the lowest latency
- Reprovisioning based on a change in the device
- Rolling the keys used by the device to connect to IoT Hub

All the source files related to the application are placed under the /source directory:

File	Description
azure_common.h	Contains public interfaces for different Azure feature tasks.
main.c	Initializes the BSP and the retarget-io library and calls the menu task.
menu_task.c	Contains functions related to user input and Azure feature task creation.
mqtt_iot_azure_device_demo_app.c	Contains functions related to Azure features - Cloud To Device, Telemetry, methods, Device Twin.
mqtt_iot_hub_pnp.c	Contains the functions related to the Azure plug and play feature.
mqtt_iot_provisioning.c	Contains the functions related to the Azure Device Provisioning Service feature.
mqtt_iot_common.c	Contains functions common to Azure applications.
mqtt_iot_common.h	Contains public interfaces common to Azure applications.
mqtt_iot_sas_token_provision.c	Contains the standalone application for provisioning Azure Device ID and SAS tokens into the secure hardware.
mqtt_main.h	Contains public interfaces related to Azure features and MQTT broker details, Wi-Fi configuration macros such as SSID, password, certificates, and keys.

All the scripts needed for this example are placed under the /scripts directory.

File	Description
dps_sas_token_generation.py	Shell script to generate SAS token for Azure Device Provisioned device
format_X509_cert_key.py	Python script to convert certificate/key to string format

Resources and settings

Table 1. Application resources

Resource	Alias/object	Purpose
SDIO (HAL)	sdio_obj	SDIO interface for Wi-Fi connectivity
UART (HAL)	cy_retarget_io_uart_obj	UART HAL object used by Retarget-IO for the Debug UART port

Related resources

Resources	Links
Application notes	AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ AN215656 – PSoC™ 6 MCU: Dual-CPU system design
Code examples	Using ModusToolbox™ on GitHub
Device documentation	PSoC™ 6 MCU datasheets PSoC™ 6 technical reference manuals
Development kits	Select your kits from the Evaluation board finder.
Libraries on GitHub	mtb-pdl-cat1 – PSoC™ 6 Peripheral Driver Library (PDL) mtb-hal-cat1 – Hardware Abstraction Layer (HAL) library retarget-io – Utility library to retarget STDIO messages to a UART port
Middleware on GitHub	psoc6-middleware – Links to all PSoC™ 6 MCU middleware mqtt – MQTT client library and documents wifi-connection-manager – Wi-Fi connection manager (WCM) library and documents wifi-mw-core – Wi-Fi middleware core library and documents freeRTOS – FreeRTOS library and documents
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.

Document history

Document title: CE234014 – Connecting to Azure IoT services using Azure SDK for Embedded C

Version	Description of change
1.0.0	New code example
2.0.0	Updated steps for X509-based Azure DPS and combined Azure IoT Hub features
2.1.0	Minor bug fixes and updated dependencies packages
3.0.0	Major update to support ModusToolbox™ v3.0 This version is not backward compatible with previous versions of ModusToolbox™
4.0.0	Removed support for CY8CKIT-064S0S2-4343W as it is replaced by CY8CKIT-064B0S2-4343W Added support for CY8CKIT-064B0S2-4343W Used the wifi-core-freertos-lwip-mbedtls repo that bundles all the core connectivity libraries Added the TF-M library into deps folder as it is now decoupled from the secure kit BSP
4.1.0	Major update to support ModusToolbox™ v3.1 Added support for CY8CPROTO-062S2-43439, CY8CEVAL-062S2-LAI-43439M2, and CY8CEVAL-062S2-MUR-4373EM2
4.2.0	Updated to support ModusToolbox™ v3.2

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deps		deps
images		images
scripts		scripts
source		source
.cyignore		.cyignore
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README.md		README.md

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Connecting to Azure IoT services using Azure SDK for Embedded C

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Supported toolchains (make variable 'TOOLCHAIN')

Supported kits (make variable 'TARGET')

Hardware setup

Software setup

Using the code example

Create the project

Open the project

Authentication credentials setup

Operation

Provisioning (DPS)

Cloud-to-device (C2D) messaging

Telemetry

Methods

Device twin

Plug and play (PnP)

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Connecting to Azure IoT services using Azure SDK for Embedded C

Requirements

Supported toolchains (make variable 'TOOLCHAIN')

Supported kits (make variable 'TARGET')

Hardware setup

Software setup

Using the code example

Create the project

Open the project

Authentication credentials setup

Operation

Provisioning (DPS)

Cloud-to-device (C2D) messaging

Telemetry

Methods

Device twin

Plug and play (PnP)

Debugging

Design and implementation

Resources and settings

Related resources

Other resources

Document history

About

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