Smart Sensor Data Publishing Node using STM32L475 and MQTT

#include "main.h"
#include "stdio.h"
#include "string.h"

/* BSP Sensor Drivers */
#include "stm32l475e_iot01_tsensor.h"
#include "stm32l475e_iot01_hsensor.h"

/* UART Handle */
UART_HandleTypeDef huart1;

/* Buffers */
char uartBuffer[100];
char mqttPayload[100];

/* Function Prototypes */
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART1_UART_Init(void);

/* MQTT Publish Function */
void MQTT_Publish_Data(float temperature)
{
    sprintf(mqttPayload,
            "{\"temperature\": %.2f}",
            temperature);

    /*
     * Replace this section with actual MQTT publish API
     *
     * Example:
     * MQTT_Publish("stm32l475/sensor/data",
     *              mqttPayload);
     */

    printf("MQTT Published: %s\n", mqttPayload);
}

/* UART Send Function */
void UART_Send(char *msg)
{
    HAL_UART_Transmit(&huart1,
                      (uint8_t*)msg,
                      strlen(msg),
                      HAL_MAX_DELAY);
}

int main(void)
{
    /* HAL Initialization */
    HAL_Init();

    /* Configure System Clock */
    SystemClock_Config();

    /* Peripheral Initialization */
    MX_GPIO_Init();
    MX_USART1_UART_Init();

    /* Initialize Sensors */
    BSP_TSENSOR_Init();
    BSP_HSENSOR_Init();

    /* Initial UART Message */
    UART_Send("System Started...\r\n");

    while (1)
    {
        float temperature;
        float humidity;

        /* Read Sensors */
        temperature = BSP_TSENSOR_ReadTemp();
        humidity = BSP_HSENSOR_ReadHumidity();

        /* Publish Temperature using MQTT */
        MQTT_Publish_Data(temperature);

        /* Send Humidity over UART */
        sprintf(uartBuffer,
                "Humidity: %.2f %%\r\n",
                humidity);

        UART_Send(uartBuffer);

        /* Delay */
        HAL_Delay(2000);
    }
}

/**
  * @brief USART1 Initialization
  */
static void MX_USART1_UART_Init(void)
{
    huart1.Instance = USART1;
    huart1.Init.BaudRate = 115200;
    huart1.Init.WordLength = UART_WORDLENGTH_8B;
    huart1.Init.StopBits = UART_STOPBITS_1;
    huart1.Init.Parity = UART_PARITY_NONE;
    huart1.Init.Mode = UART_MODE_TX_RX;
    huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    huart1.Init.OverSampling = UART_OVERSAMPLING_16;

    if (HAL_UART_Init(&huart1) != HAL_OK)
    {
        Error_Handler();
    }
}

/**
  * @brief GPIO Initialization
  */
static void MX_GPIO_Init(void)
{
    __HAL_RCC_GPIOA_CLK_ENABLE();
    __HAL_RCC_GPIOB_CLK_ENABLE();
}

/**
  * @brief System Clock Configuration
  */
void SystemClock_Config(void)
{
    /* Auto-generated by CubeMX */
}

/**
  * @brief Error Handler
  */
void Error_Handler(void)
{
    while (1)
    {
    }
}