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• NanoDrone II workshop
• PSoC6 firmware documentation series

• ModusToolbox® software v2.4

  Note: This code example version requires ModusToolbox software version 2.4 or later and is not backward compatible with v2.1 or older versions. If you cannot move to ModusToolbox v2.2, use the latest compatible version of this example: latest-v1.X.

• Board Support Package (BSP) minimum required version: 2.0.0

• Programming Language: C

• Associated Parts: All PSoC® 6 MCU parts with SDIO, CYW43012, CYW4343W

• GNU Arm® Embedded Compiler v9.3.1 (GCC_ARM) - Default value of TOOLCHAIN
• IAR C/C++ compiler v8.32.2 (IAR)

• PSoC 6 Wi-Fi BT Prototyping Kit (CY8CPROTO-062-4343W) - Default value of TARGET
• PSoC 62S2 Wi-Fi BT Pioneer Kit (CY8CKIT-062S2-43012)

Note: This project requires PSoC 6 device with at least 2 MB flash and 1 MB SRAM and therefore does not support other PSoC 6 MCU kits.

This example uses the board's default configuration. See the kit user guide to ensure that the board is configured correctly. Connect a UART signal to 10.0, 9600 / 8 / 1 / N

Install a terminal emulator if you don't have one. Instructions in this document use Tera Term.

This example requires no additional software or tools.

1. Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.

2. 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 as follows:

      • For AWS IoT MQTT:

        1. 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, it is recommended to have 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": "*"
                   }
               ]
           }
           

        2. 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.

        3. 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.

        4. 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.

      • For public Mosquitto Broker:

        Note: The public test MQTT Broker at test.mosquitto.org uses the SHA-1 hashing algorithm for certificate signing. As cautioned by Mbed TLS, SHA-1 is considered a weak message digest. The use of SHA-1 for certificate signing constitutes a security risk. It is recommended to avoid dependencies on it, and consider stronger message digests instead.

        Note that this code example enables SHA-1 support in Mbed TLS and MQTT Client libraries in order to support secure TLS-based connections to the public test MQTT Broker as described here.

        1. Set MQTT_BROKER_ADDRESS as "test.mosquitto.org".

        2. Set AWS_IOT_MQTT_MODE to 0 as you are connecting to an MQTT Broker other than AWS IoT.

        3. For a secure connection that requires client authentication using TLS (port 8884), configure as follows:

           • MQTT_PORT as 8884.

           • MQTT_SECURE_CONNECTION as 1.

           • Generate the client certificate and the private key according to the instructions from test.mosquitto.org. The root CA certificate is available here.

             Using the client certificate, private key, and root CA certificate, 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.

           • In the application Makefile, set the variable ENABLE_SECURE_MOSQUITTO_BROKER_SUPPORT as 1 to enable SHA-1 support.

           For non-TLS connections (port 1883), configure the macros as follows:

           • MQTT_PORT as 1883.
           • MQTT_SECURE_CONNECTION as 0.

      • Other MQTT Client configuration macros:

        1. MQTT_TOPIC_NANODRONE: The MQTT topic common to both the Publisher and Subscriber in this example.
        2. ENABLE_LWT_MESSAGE: Set to 1 to use MQTT's Last Will and Testament (LWT) feature. This is an MQTT message that will be published by the MQTT Broker if the MQTT connection is unexpectedly closed.
        3. 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.

      Although this code example provides instructions only for AWS IoT and public test Mosquitto Broker, the MQTT Client implemented in this example is generic. It is expected to work with other MQTT Brokers (see the list of publicly-accessible MQTT Brokers) with appropriate configurations.

   3. Other configuration files: You can optionally modify the configuration macros in the following files according to your application:

      • configs/iot_config.h used by the MQTT library
      • configs/FreeRTOSConfig.h used by the FreeRTOS library

3. Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.

4. Program the board.

   • 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).

   • Using CLI:

     From the terminal, execute the make program command to build and program the application using the default toolchain to the default target. You can specify a target and toolchain manually:

     make program TARGET=<BSP> TOOLCHAIN=<toolchain>
     

     Example:

     make program TARGET=CY8CKIT-062S2-43012 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.

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 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 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.

Before using the project without the debugger attached, program it with the release binary.

In the IDE, use the <Application Name> Program (KitProg3_MiniProg4) configuration in the Quick Panel.

This project implements three RTOS tasks: MQTT Client, Publisher, and (optionally via MQTT_SUBSCRIBE in mqtt_task.c) Subscriber. 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_TOPIC_NANODRONE macro that can be configured in mqtt_topic_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 turns the user LED ON or OFF depending on whether the received message is "TURN ON" or "TURN OFF".

The UART task sets up UART_1 and configures an interrupt for receiving 26 bytes. The ISR notifies the UART task upon data receiving.

The data is pushed on the telemetry queue and wakes up the Publisher task.

The Publisher task then publishes payload on the topic specified by the MQTT_TOPIC_NANODRONE macro. When the publish operation fails, a message is sent over a queue to the MQTT Client task.

When a failure has been encountered, 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.

####payload datagram

The payload is a 26 bytes (ascii characters) array and contains:

1. longitude +9999999 (5 decimals)
2. latitude +99999999 (5 decimals)
3. time hhmmss
4. image rating 999

Table 1. Application Resources

Cypress provides a wealth of data at www.cypress.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 Cypress community.

Document Title: Nanodrone II PSoC6 - UART to MQTT

From Document Title: CE229889 - AnyCloud Example: MQTT Client

Password login decomissioned 31/8/2021

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