MQTT client with XENSIV™ sensors: BGT60TR13C 60-GHz radar

Overview

This code example demonstrates implementing an MQTT client using the MQTT client library for XENSIV™ sensors with Infineon connectivity devices. The library uses the following:

AWS IoT device SDK MQTT client library that includes an MQTT 3.1.1 client
RadarSensing library configured for presence detection application

In this example, the MQTT client RTOS task establishes a connection with the configured MQTT broker, and creates three tasks - publisher, subscriber, and radar. The publisher task publishes messages on the MQTT_PUB_TOPIC topic when radar events are detected. The subscriber task subscribes to MQTT_SUB_TOPIC. The radar task initializes the RadarSensing context object for detecting presence, registers a callback to handle presence detection events, and continuously processes the data acquired from the radar.

From 'radar_task', there is another radar configuration task created to enable configuring the RadarSensing library dynamically. From the MQTT broker, you can send a JSON message to the MQTT client within MQTT_SUB_TOPIC to perform the configuration.

View this README on GitHub.

Provide feedback on this code example.

Sequence of operation

One of the following radar events occurs: presence, absence, or counter event. At the same time, the LED indicates other events. For details, see Table 2.
The radar sensing callback function notifies the publisher task.
The publisher task publishes this event to the remote server on a defined topic. You can verify this data from the MQTT broker.
The MQTT broker sends the configuration as a JSON string to this client to configure the 'xensiv-radar-sensing' library. This allows remote configuration.

Requirements

ModusToolbox™ software v2.4 or later (tested with v2.4)
Board support package (BSP) minimum required version: 3.0.0
Programming language: C
Associated parts: All PSoC™ 6 MCU parts with SDIO, AIROC™ CYW43012 Wi-Fi & Bluetooth® combo chip, AIROC™ CYW4343W Wi-Fi & Bluetooth® combo chip

Supported toolchains (make variable 'TOOLCHAIN')

GNU Arm® embedded compiler v10.3.1 (GCC_ARM) - Default value of TOOLCHAIN
Arm® compiler v6.13 (ARM)
IAR C/C++ compiler v8.42.2 (IAR)

Supported kits (make variable 'TARGET')

Rapid IoT connect developer kit (CYSBSYSKIT-DEV-01) - Default value of TARGET

Note: This example requires PSoC™ 6 MCU devices with at least 2-MB flash and 1-MB SRAM and therefore does not support other PSoC™ 6 MCU kits.

Hardware setup

This code example requires the XENSIV™ Radar wing board as part of the connected sensor kit.

Connect the Radar wing board to the CYSBSYSKIT-DEV-01 kit with the pin headers.
Connect the CYSBSYSKIT-DEV-01 kit to the PC with a USB cable.
Place the CYSBSYSKIT-DEV-01 kit at a location which is suitable for testing.

Rapid IoT connect platform RP01 feather kit (CYSBSYSKIT-DEV-01)

XENSIV&trade Radar wing board

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

Software setup

Install a terminal emulator if you do not have one. Instructions in this document use Tera Term.

This code example implements a generic MQTT client that can connect to various MQTT brokers. In this document, the instructions to set up and run the MQTT client have been provided for the AWS IoT and Mosquitto MQTT brokers for reference. If you are using this code example with Mosquitto broker running locally on your PC, you need to download and install Mosquitto broker from https://mosquitto.org/download.

This example requires no additional software or tools if you are using the MQTT client with a publicly hosted MQTT broker.

Using the code example

Create the project and open it using one of the following:

In Eclipse IDE for ModusToolbox™ software

Click the New Application link in the Quick Panel (or, use File > New > ModusToolbox Application). This launches the Project Creator tool.
Pick a kit supported by the code example from the list shown in the Project Creator - Choose Board Support Package (BSP) dialog.

When you select a supported kit, the example is reconfigured automatically to work with the kit. To work with a different supported kit later, use the Library Manager to choose the BSP for the supported kit. You can use the Library Manager to select or update the BSP and firmware libraries used in this application. To access the Library Manager, click the link from the Quick Panel.

You can also just start the application creation process again and select a different kit.

If you want to use the application 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.
In the Project Creator - Select Application dialog, choose the example by enabling the checkbox.
(Optional) Change the suggested New Application Name.
The Application(s) Root Path defaults to the Eclipse workspace which is usually the desired location for the application. If you want to store the application in a different location, you can change the Application(s) Root Path value. Applications that share libraries should be in the same root path.
Click Create to complete the application creation process.

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

In command-line interface (CLI)

ModusToolbox™ software provides the Project Creator as both a GUI tool and the command line tool, "project-creator-cli". The 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™ software 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™ software installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ software 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.

This tool has the following arguments:

Argument	Description	Required/optional
`--board-id`	Defined in the `<id>` field of the BSP manifest	Required
`--app-id`	Defined in the `<id>` 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

The following example will clone the "mtb-example-sensors-radar-anycloud-mqtt-client" application with the desired name "SensorRadarMQTT" configured for the CYSBSYSKIT-DEV-01 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CYSBSYSKIT-DEV-01 --app-id mtb-example-sensors-radar-anycloud-mqtt-client --user-app-name SensorRadarMQTT --target-dir "C:/mtb_projects"

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™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

In third-party IDEs

Use one of the following options:

Use the standalone Project Creator tool:
1. Launch Project Creator from the Windows Start menu or from {ModusToolbox™ software install directory}/tools_{version}/project-creator/project-creator.exe.
2. In the initial Choose Board Support Package screen, select the BSP, and click Next.
3. In the Select Application screen, select the appropriate IDE from the Target IDE drop-down menu.
4. Click Create and follow the instructions printed in the bottom pane to import or open the exported project in the respective IDE.

Use command-line interface (CLI):
1. Follow the instructions from the In command-line interface (CLI) section to create the application, and then import the libraries using the make getlibs command.
2. Export the application to a supported IDE using the make <ide> command.
3. Follow the instructions displayed in the terminal to create or import the application as an IDE project.

For a list of supported IDEs and more details, see the "Exporting to IDEs" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

Note: There are two working modes for the RadarSensing library: presence sensing and entrance counter. You can switch the working mode at compile time by define or undef RADAR_ENTRANCE_COUNTER_MODE inside radar_task.h. By default, it works in the presence sensing mode.

Operation

Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
Modify the user configuration files in the configs directory as follows:
1. Wi-Fi configuration: Set the Wi-Fi credentials in configs/wifi_config.h: Modify the macros WIFI_SSID, WIFI_PASSWORD, and WIFI_SECURITY to match with that of the Wi-Fi network that you want to connect.
2. MQTT configuration: Set up the MQTT client and configure the credentials in configs/mqtt_client_config.h. Some of the important configuration macros are as follows:
  - MQTT_BROKER_ADDRESS: Hostname of the MQTT broker
  - MQTT_PORT: Port number to be used for the MQTT connection. As specified by Internet Assigned Numbers Authority (IANA), port numbers assigned for MQTT protocol are 1883 for non-secure connections and 8883 for secure connections. However, MQTT brokers may use other ports. Configure this macro as specified by the MQTT broker.
  - MQTT_SECURE_CONNECTION: Set this macro to 1 if a secure (TLS) connection to the MQTT broker is required to be established; else 0.
  - MQTT_USERNAME and MQTT_PASSWORD: Username and password for client authentication and authorization, if required by the MQTT broker. However, note that this information is generally not encrypted and the password is sent in plain text. Therefore, this is not a recommended method of client authentication.
  - CLIENT_CERTIFICATE and CLIENT_PRIVATE_KEY: Certificate and private key of the MQTT client used for client authentication. Note that these macros are applicable only when MQTT_SECURE_CONNECTION is set to 1.
  - ROOT_CA_CERTIFICATE: Root CA certificate of the MQTT broker
  See Setting up the MQTT broker to learn how to configure these macros for AWS IoT and Mosquitto MQTT brokers.
  
  For a full list of configuration macros used in this code example, see Wi-Fi and MQTT configuration macros.
3. Other configuration files: You can optionally modify the configuration macros in the following files according to your application:
  - configs/core_mqtt_config.h used by the MQTT library
  - configs/FreeRTOSConfig.h used by the FreeRTOS library
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 for ModusToolbox™ software
1. Select the application project in the Project Explorer.
2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).
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 and target are specified in the application's Makefile but you can override those values manually:
```
make program TARGET=<BSP> TOOLCHAIN=<toolchain>
```
Example:
```
make program TARGET=CYSBSYSKIT-DEV-01 TOOLCHAIN=GCC_ARM
```
After programming, the application starts automatically. Observe the messages on the UART terminal, and wait for the device to make all the required connections.

Figure 1. UART terminal showing the application initialization status
Once the initialization is complete, confirm that subscription to the topic is successful.
If the radar wing board is connected and it detects a sensor event, the following messages are displayed in the terminal:

Figure 2. Radar event detected

Do the following if a radar event is detected:

For AWS IoT MQTT

Go to AWS IoT-core on the bar on the left.
Open the MQTT test client from the Test menu to subscribe to the MQTT_PUB_TOPIC topic, which is radar_status. See Figure 3.

Figure 3. Radar event detected message on the MQTT broker

When you configure the device from the MQTT broker (see the first half of Figure 4), the configuration JSON message will be sent to the device within MQTT_SUB_TOPIC. The message will be printed out in the terminal. In addition, the device will check and apply the configuration, and give feedback to the MQTT broker (see the second half of Figure 4).

Figure 4. Receive configuration message on the MQTT broker

Note: The warning message appears only because the received message is not in JSON format.

Figure 5. Receive configuration message

For public Mosquitto broker

Run Windows console or Cygwin and go to the directory with mosquitto. Typically it should be in C:\Program Files\mosquitto

Subscribe to the topic radar_status by running

mosquitto_sub -t radar_status -h test.mosquitto.org

When the radar detects an object, the message will appear on the terminal.

Figure 6. Mosquitto broker sending radar event

Next try to configure radar by publishing valid JSON on the radar_config topic. To do this, run the second console, go to the same directory and run:
```
mosquitto_pub -h test.mosquitto.org -p 1883 -t radar_config -m "{\"radar_presence_range_max\":1.5}"
```

Then you will see the information that radar successfully changed its parameter.

Figure 7. Mosquitto broker sending radar configuration

Table 1. Configuration JSON objects

(See XENSIV™ RadarSensing library documentation)

Key	Default value	Valid values
Presence sensing
`radar_presence_range_max`	"2.0"	0.66 - 10.2 m
`radar_presence_sensitivity`	"medium"	"low", "medium", "high"
Entrance counter
`radar_counter_installation`	"side"	"ceiling", "side"
`radar_counter_orientation`	"portrait"	"portrait", "landscape"
`radar_counter_ceiling_height`	"2.5"	0.0 - 3.0 m
`radar_counter_entrance_width`	"1.0"	0.0 - 3.0 m
`radar_counter_sensitivity`	"0.5"	0.0 - 1.0
`radar_counter_traffic_light_zone`	"1.0"	0.0 - 1.0 m
`radar_counter_reverse`	"false"	"true", "false"
`radar_counter_min_person_height`	"1.0"	0.0 - 2.0 m
`radar_counter_in_number`	"0"	any non-negative integer (32-bit)
`radar_counter_out_number`	"0"	any non-negative integer (32-bit)

Confirm that the following messages are printed when no wing boards are connected.

Figure 8. No wing board connected

This example can be programmed on multiple kits (Only when GENERATE_UNIQUE_CLIENT_ID is set to 1).

Alternatively, the publish and subscribe functionalities of the MQTT client can be individually verified if the MQTT broker supports a Test MQTT client such as the AWS IoT.

Do one of the following:

To verify the subscribe functionality: Using the Test MQTT client, publish messages on the topic specified by the MQTT_SUB_TOPIC macro in mqtt_client_config.h.
To verify the publish functionality: From the Test MQTT client, subscribe to the MQTT topic specified by the MQTT_PUB_TOPIC macro and confirm that the messages published by the kit are displayed on the Test MQTT client's console.

Sensor information and LEDs

The radar task is suspended if the radar wing board is not connected to the feather kit. The sensor initialization process is indicated by blinking the red LED (CYBSP_USER_LED) on CYSBSYSKIT-DEV-01. The red LED (CYBSP_USER_LED) on CYSBSYSKIT-DEV-01 remains turned ON when system is operational (ready state).

The LED indicates different events with different patterns as follows:

Table 2. Events and LED glow patterns

LED pattern	Event type	Comment
Presence sensing
LED glows in red color	`MTB_RADAR_SENSING_EVENT_PRESENCE_IN`	Presence event detected. Entering the field of view
LED stable in green color	`MTB_RADAR_SENSING_EVENT_PRESENCE_OUT`	Presence event detected. Leaving the filed of view
Entrance counter
LED glows in red color	`MTB_RADAR_SENSING_EVENT_COUNTER_OCCUPIED`	Counter event detected. Entering the field of view
LED glows in green color	`MTB_RADAR_SENSING_EVENT_COUNTER_FREE`	Counter event detected. Leaving the field of view
LED blinking in red/green color	`MTB_RADAR_SENSING_EVENT_COUNTER_IN` or `MTB_RADAR_SENSING_EVENT_COUNTER_OUT`	Depends on the installation position to determine which scenario is IN, which is OUT

Debugging

You can debug the example to step through the code. In the 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™ software 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.

Design and implementation

This example implements three RTOS tasks: MQTT client, publisher, subscriber, radar task, radar configuration task, and led task. The main function initializes the BSP and the retarget-io library, and creates the MQTT client task.

The MQTT client task initializes the Wi-Fi connection manager (WCM) and connects to a Wi-Fi access point (AP) using the Wi-Fi network credentials that are configured in wifi_config.h. Upon a successful Wi-Fi connection, the task initializes the MQTT library and establishes a connection with the MQTT broker/server.

The MQTT connection is configured to be secure by default; the secure connection requires a client certificate, a private key, and the root CA certificate of the MQTT broker that are configured in mqtt_client_config.h.

After a successful MQTT connection, the subscriber and publisher tasks are created. The MQTT client task then waits for messages from the other two tasks and callbacks, and handles the cleanup operations of various libraries if the messages indicate failure.

The subscriber task subscribes to messages on the topic specified by the MQTT_SUB_TOPIC macro that can be configured in mqtt_client_config.h. When the subscribe operation fails, a message is sent to the MQTT client task over a message queue. When the subscriber task receives a message from the broker, it prints the information.

The radar sensing callback function notifies the publisher task upon a radar event. The publisher task then publishes messages (PRESENCE IN/PRESENCE OUT) on the topic specified by the MQTT_PUB_TOPIC macro. When the publish operation fails, a message is sent over a queue to the MQTT client task.

When a failure occurs, the MQTT client task handles the cleanup operations of various libraries, thereby terminating any existing MQTT and Wi-Fi connections and deleting the MQTT, publisher, and subscriber tasks.

Configuring the MQTT client

Wi-Fi and MQTT configuration macros

Macro	Description
Wi-Fi Connection Configurations	In configs/wifi_config.h
`WIFI_SSID`	SSID of the Wi-Fi AP to which the MQTT client connects
`WIFI_PASSWORD`	Passkey/password for the Wi-Fi SSID specified above
`WIFI_SECURITY`	Security type of the Wi-Fi AP. See `cy_wcm_security_t` structure in cy_wcm.h for details.
`MAX_WIFI_CONN_RETRIES`	Maximum number of retries for Wi-Fi connection
`WIFI_CONN_RETRY_INTERVAL_MS`	Time interval in milliseconds in between successive Wi-Fi connection retries
MQTT Connection Configurations	In configs/mqtt_client_config.h
`MQTT_BROKER_ADDRESS`	Hostname of the MQTT broker
`MQTT_PORT`	Port number to be used for the MQTT connection. As specified by IANA, port numbers assigned for MQTT protocol are 1883 for non-secure connections and 8883 for secure connections. However, MQTT brokers may use other ports. Configure this macro as specified by the MQTT broker.
`MQTT_SECURE_CONNECTION`	Set this macro to 1 if a secure (TLS) connection to the MQTT broker is required to be established; else 0.
`MQTT_USERNAME` `MQTT_PASSWORD`	Username and password for client authentication and authorization, if required by the MQTT broker. However, note that this information is generally not encrypted and the password is sent in plain text. Therefore, this is not a recommended method of client authentication.
MQTT Client Certificate Configurations	In configs/mqtt_client_config.h
`CLIENT_CERTIFICATE` `CLIENT_PRIVATE_KEY`	Certificate and private key of the MQTT client used for client authentication. Note that these macros are applicable only when `MQTT_SECURE_CONNECTION` is set to 1.
`ROOT_CA_CERTIFICATE`	Root CA certificate of the MQTT broker
MQTT Message Configurations	In configs/mqtt_client_config.h
`MQTT_PUB_TOPIC`	MQTT topic to which the messages are published by the publisher task to the MQTT broker
`MQTT_SUB_TOPIC`	MQTT topic to which the subscriber task subscribes to. The MQTT broker sends the messages to the subscriber that are published in this topic (or equivalent topic).
`MQTT_MESSAGES_QOS`	The Quality of Service (QoS) level to be used by the publisher and subscriber. Valid choices are 0, 1, and 2.
`ENABLE_LWT_MESSAGE`	Set this macro to 1 if you want to use the 'Last Will and Testament (LWT)' option; else 0. LWT is an MQTT message that will be published by the MQTT broker on the specified topic if the MQTT connection is unexpectedly closed. This configuration is sent to the MQTT broker during MQTT connect operation; the MQTT broker will publish the Will message on the Will topic when it recognizes an unexpected disconnection from the client.
`MQTT_WILL_TOPIC_NAME` `MQTT_WILL_MESSAGE`	The MQTT topic and message for the LWT option described above. These configurations are applicable only when `ENABLE_LWT_MESSAGE` is set to 1.
`MQTT_DEVICE_ON_MESSAGE` `MQTT_DEVICE_OFF_MESSAGE`	The MQTT messages that control the device (LED) state in this code example.
Other MQTT Client Configurations	In configs/mqtt_client_config.h
`GENERATE_UNIQUE_CLIENT_ID`	Every active MQTT connection must have a unique client identifier. If this macro is set to 1, the device will generate a unique client identifier by appending a timestamp to the string specified by the `MQTT_CLIENT_IDENTIFIER` macro. This feature is useful if you are using the same code on multiple kits simultaneously.
`MQTT_CLIENT_IDENTIFIER`	The client identifier (client ID) string to be used during MQTT connection. If `GENERATE_UNIQUE_CLIENT_ID` is set to 1, a timestamp is appended to this macro value and used as the client ID; else, the value specified for this macro is directly used as the client ID.
`MQTT_CLIENT_IDENTIFIER_MAX_LEN`	The longest client identifier that an MQTT server must accept (as defined by the MQTT 3.1.1 spec) is 23 characters. However, some MQTT brokers support longer client IDs. Configure this macro as per the MQTT broker specification.
`MQTT_TIMEOUT_MS`	Timeout in milliseconds for MQTT operations in this example
`MQTT_KEEP_ALIVE_SECONDS`	The keepalive interval in seconds used for MQTT ping request
`MQTT_ALPN_PROTOCOL_NAME`	The application layer protocol negotiation (ALPN) protocol name to be used that is supported by the MQTT broker in use. Note that this is an optional macro for most of the use cases. Per IANA, the port numbers assigned for MQTT protocol are 1883 for non-secure connections and 8883 for secure connections. In some cases, there is a need to use other ports for MQTT such as port 443 (which is reserved for HTTPS). ALPN is an extension to TLS that allows many protocols to be used over a secure connection.
`MQTT_SNI_HOSTNAME`	The server name indication (SNI) host name to be used during the transport layer security (TLS) connection as specified by the MQTT broker. SNI is extension to the TLS protocol. As required by some MQTT brokers, SNI typically includes the hostname in the "Client Hello" message sent during TLS handshake.
`MQTT_NETWORK_BUFFER_SIZE`	A network buffer is allocated for sending and receiving MQTT packets over the network. Specify the size of this buffer using this macro. Note that the minimum buffer size is defined by the `CY_MQTT_MIN_NETWORK_BUFFER_SIZE` macro in the MQTT library.
`MAX_MQTT_CONN_RETRIES`	Maximum number of retries for MQTT connection
`MQTT_CONN_RETRY_INTERVAL_MS`	Time interval in milliseconds in between successive MQTT connection retries

Setting up the MQTT broker

AWS IoT MQTT

Set up the MQTT device (also known as a Thing) in the AWS IoT core as described in the Getting started with AWS IoT tutorial.

Note: While setting up your device, ensure that the policy associated with this device permits all MQTT operations (iot:Connect, iot:Publish, iot:Receive, and iot:Subscribe) for the resource used by this device. For testing purposes, use the following policy document which allows all MQTT Policy Actions on all Amazon Resource Names (ARNs).
```
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "iot:*",
            "Resource": "*"
        }
    ]
}
```
In the configs/mqtt_client_config.h file, set MQTT_BROKER_ADDRESS to your custom endpoint on the Settings page of the AWS IoT console. This has the format ABCDEFG1234567.iot.<region>.amazonaws.com.
Set the macros MQTT_PORT to 8883 and MQTT_SECURE_CONNECTION to 1 in the configs/mqtt_client_config.h file.
Download the following certificates and keys that are created and activated in the previous step:
- A certificate for the AWS IoT Thing - xxxxxxxxxx.cert.pem
- A public key - xxxxxxxxxx.public.key
- A private key - xxxxxxxxxx.private.key
- Root CA "RSA 2048 bit key: Amazon Root CA 1" for AWS IoT from CA certificates for server authentication.
Using these certificates and keys, enter the following parameters in mqtt_client_config.h in Privacy-Enhanced Mail (PEM) format:
- CLIENT_CERTIFICATE - xxxxxxxxxx.cert.pem
- CLIENT_PRIVATE_KEY - xxxxxxxxxx.private.key
- ROOT_CA_CERTIFICATE - Root CA certificate
You can either convert the values to strings manually following the format shown in mqtt_client_config.h or you can use the HTML utility available here to convert the certificates and keys from PEM format to C string format. You need to clone the repository from GitHub to use the utility.

Local Mosquitto broker

Download and install the Mosquitto broker for your PC from https://mosquitto.org/download. The following instructions help in setting up the Mosquitto broker for a secure connection with the client using self-signed SSL certificates. This requires OpenSSL which is already preloaded in the ModusToolbox™ software installation. Run the following commands with a CLI (on Windows, use the command line "modus-shell" program provided in the ModusToolbox™ software installation instead of the standard Windows command-line application).

Generate the CA certificate for the Mosquitto broker / server using the following commands. Follow the instructions in the command window to provide the details required.
```
openssl genrsa -out ca.key 2048
openssl req -new -x509 -sha256 -nodes -days 365 -key ca.key -out ca.crt
```
Generate the server key pair and server certificate (signed using the CA certificate from Step 1) for the Mosquitto broker using the following commands. Follow the instructions in the command window to provide the details required.
```
openssl genrsa -out server.key 2048
openssl req -new -nodes -sha256 -key server.key -out server.csr
openssl x509 -req -sha256 -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 365
```
At this stage, the certificates and keys required by the Mosquitto broker are ready. The files used from these steps are ca.crt, server.crt, and server.key.

Create a configuration file for the Mosquitto broker - mosquitto.conf with the following contents and provide the path to the generated credentials (ca.crt, server.crt, and server.key) under the SSL settings section.

# Config file for mosquitto
connection_messages true
per_listener_settings true
listener 8883
require_certificate true
use_identity_as_username true
allow_anonymous false
cafile <path-to-ca.crt>
keyfile <path-to-server.key>
certfile <path-to-server.crt>

Start the Mosquitto broker with the configurations from the above mosquitto.conf file using the following command. If the mosquitto.conf file is present in a different location from where the command is run, provide the path to the config file after the -c argument.
```
mosquitto -v -c mosquitto.conf
```
Generate the client certificates using the following commands. Follow the instructions in the command window to provide the details required. Note that the last command requires ca.crt and ca.key files generated in Step 2.
```
openssl genrsa -out client.key 2048
openssl req -new -out client.csr -key client.key
openssl x509 -req -in client.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out client.crt -days 365
```
Configure the MQTT client configurations in configs/mqtt_client_config.h as follows:
- MQTT_BROKER_ADDRESS as the IP address of the PC running the Mosquitto broker (the PC on which Step 4 is performed).
- MQTT_PORT as 8883.
- MQTT_SECURE_CONNECTION as 1.
- Using the client certificate (client.crt), private key (client.key), and root CA certificate (ca.crt) from the above steps, configure the CLIENT_CERTIFICATE, CLIENT_PRIVATE_KEY, and ROOT_CA_CERTIFICATE macros respectively.
  
  You can either convert the PEM format values to strings manually following the format shown in mqtt_client_config.h or you can use the HTML utility available here to convert the certificates and keys from PEM format to C string format. You need to clone the repository from GitHub to use the utility.

Although this section provides instructions only for AWS IoT and the local Mosquitto broker, the MQTT client implemented in this example is generic. It is expected to work with other MQTT brokers with appropriate configurations. See the list of publicly-accessible MQTT brokers that can be used for testing and prototyping purposes.

Resources and settings

Table 3. Application source files

File name	Comments
main.c	Contains the application entry point. It initializes the UART for debugging and then initializes the controller tasks
mqtt_client_config.c	Global variables for MQTT connection
mqtt_task.c	Contains the task function to do the following: 1. Establish an MQTT connection 2. Start the publisher and subscriber tasks 3. Start the radar task
publisher_task.c	Contains the task function to publish message to the MQTT broker
subscriber_task.c	Contains the task function to subscribe message from the MQTT broker
radar_task.c	Contains the task function for the presence and entrance counter application (select at compile time), as well as the callback function
radar_config_task.c	Contains the task function to configure the xensiv-radar-sensing library
radar_led_task.c	Contains the task function that handles the LEDs

Related resources

Resources	Links
Application notes	AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ software AN215656 – PSoC™ 6 MCU: Dual-CPU system design
Code examples	Using ModusToolbox™ software on GitHub
Device documentation	PSoC™ 6 MCU datasheets PSoC™ 6 technical reference manuals
Development kits	CYSBSYSKIT-DEV-01 Rapid IoT connect developer kit
Libraries on GitHub	xensiv-radar-sensing – RadarSensing library to detect presence and count people using XENSIV™ BGT60TR13C 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	mqtt – MQTT client library and docs wifi-connection-manager – Wi-Fi connection manager (WCM) library and docs wifi-mw-core – Connectivity utilities and docs psoc6-middleware – Links to all PSoC™ 6 MCU middleware
Tools	Eclipse IDE for ModusToolbox™ software – ModusToolbox™ software is a collection of easy-to-use software and tools enabling rapid development with Infineon MCUs, covering applications from embedded sense and control to wireless and cloud-connected systems using AIROC™ Wi-Fi and Bluetooth® connectivity devices.

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 PSoC™ 6 MCU devices, see How to design with PSoC™ 6 MCU - KBA223067 in the Infineon community.

Document history

Document title: CE233237 – MQTT client with XENSIV™ sensors: BGT60TR13C 60-GHz radar

Version	Description of change
0.5.0	New code example
1.0.0	Update to: 1. Support xensiv-radar-sensing v1.X library. 2. Reduce drive strength to improve EMI.
1.1.0	Update to: 1. Update to TARGET_CYSBSYSKIT-DEV-01 latest-v3.X. 2. Add IAR/Arm® compiler support.

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mtb-example-sensors-radar-mqtt-client/README.md