AWS MQTT Demo

This demo application connects to AWS IoT through MQTT, subscribes to topics and publishes messages.

It requires an active and properly configured thing.

You can use the AWS IoT MQTT client in the AWS IoT console to watch the MQTT messages sent and received by AWS IoT.

The following describes the various components and the configuration settings.

Once the application is configured you can:

• Build the application
• Connect the debugger
• Run the application and view messages in a debug printf or terminal window

AWS IoT Client

The file iot_config.h configures the connection to AWS IoT with these settings:

• IOT_DEMO_SERVER: Remote Host
• IOT_DEMO_ROOT_CA: Trusted Server Root Certificate
• IOT_DEMO_CLIENT_CERT: Client Certificate
• IOT_DEMO_PRIVATE_KEY: Client Private Key
• IOT_DEMO_IDENTIFIER: Thing Identifier

Note: These settings need to be configured by the user!

FreeRTOS Real-Time Operating System

The FreeRTOS RTOS implements the resource management. It is configured with the following settings:

• Global Dynamic Memory size: 24000 bytes
• Default Thread Stack size: 3072 bytes

WiFi IoT Socket

This implementation uses an IoT socket layer that connects to a CMSIS-Driver WiFi.

The file socket_startup.c configures the WiFi connection with these settings:

• SSID: network identifier
• PASSWORD: network password
• SECURITY_TYPE: network security

Note: These settings need to be configured by the user!

ESP8266 WiFi Module

The ESP8266 WiFi Module is connected via an Arduino connector using a USART interface. It exposes a CMSIS-Driver WiFi.

STMicroelectronics NUCLEO-L552ZE-Q Target Board

The Board layer contains the following configured interface drivers:

CMSIS-Driver USART6 routed to Virtual COM port (ST-LINK):

• RX: ST-LINK-LPUART1_RX (PG8)
• TX: ST-LINK-LPUART1_TX (PG7)

CMSIS-Driver USART3 routed to Arduino UNO R3 connector (CN10):

• RX: D0 USART_A_RX (PD9)
• TX: D1 USART_A_TX (PD8)

CMSIS-Driver SPI1 routed to Arduino UNO R3 connector (CN7):

• SCK: D13 SPI_A_SCK (PA5)
• MISO: D12 SPI_A_MISO (PA6)
• MOSI: D11 SPI_A_MOSI (PA7)

GPIO pins routed to Arduino UNO R3 connector (CN7):

• output: D10 SPI_A_CS (PD14)
• input: D9 TIM_B_PWM2 (PD15)

CMSIS-Driver VIO with the following board hardware mapping:

• vioBUTTON0: Button USER (PC13)
• vioLED0: LD3 RED (PA9)
• vioLED1: LD1 GREEN (PC7)
• vioLED2: LD2 BLUE (PB7)

STDIO routed to Virtual COM port (ST-LINK, baudrate = 115200)

The board configuration can be modified using STM32CubeMX and is stored in the file STCubeGenerated.ioc.