Google MQTT Demo

This demo application connects to Google Cloud IoT through MQTT and publishes messages.

It requires a registered device in the Google Cloud 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

Google IoT Client

The file demo.c configures the connection to Google IoT with these settings:

• PROJECT_ID: Project ID
• CLOUD_REGION: Cloud region
• REGISTRY_ID: Registry ID
• DEVICE_ID: Device ID

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

The file pkey.h configures the device private key.

Note: The device private key needs to be provided 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.

NXP LPCXpresso55S69 Target Board

The Board layer contains the following configured interface drivers:

CMSIS-Driver USART2 routed to Arduino UNO R3 connector (P18):

• RX: D0 (PLU_OUT6/GPIO/FC2_USART_RXD_ARD)
• TX: D1 (FC2_USART_TXD_ARD)

CMSIS-Driver SPI8 routed to Arduino UNO R3 connector (P17):

• SCK: D13 (LSPI_HS_SCK)
• MISO: D12 (LSPI_HS_MISO)
• MOSI: D11 (LSPI_HS_MOSI)

GPIO pins routed to Arduino UNO R3 connector (P17):

• output: D10 (LSPI_HS_SSEL1)
• input: D9 (PIO1_5_GPIO_ARD)

CMSIS-Driver VIO with the following board hardware mapping:

• vioBUTTON0: Button USER (PIO1_9)
• vioLED0: LED RED (PIO1_6)
• vioLED1: LED GREEN (PIO1_7)
• vioLED2: LED BLUE (PIO1_4)

STDIO routed to Virtual COM port (DAP-Link, baudrate = 115200)

The board configuration can be modified using MCUxpresso and is stored in the file LPCXpresso55S69.mex.