Smart Sensor Data Publishing Node using STM32L475 IoT Node

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Smart Sensor Data Publishing Node
  ******************************************************************************
  * This project:
  * 1. Reads HTS221 temperature sensor data
  * 2. Publishes temperature data using MQTT
  * 3. Reads LPS22HB pressure sensor data
  * 4. Sends pressure data over UART
  ******************************************************************************
  */
/* USER CODE END Header */

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

/* BSP Sensor Drivers */
#include "hts221.h"
#include "lps22hb.h"

/* UART Handle */
UART_HandleTypeDef huart2;

/* I2C Handle */
I2C_HandleTypeDef hi2c1;

/* Variables */
float temperature = 0.0;
float humidity = 0.0;
float pressure = 0.0;

char uartBuffer[100];
char mqttPayload[100];

/* Function Prototypes */
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);
static void MX_I2C1_Init(void);

/* USER CODE BEGIN 0 */

/* Dummy MQTT Publish Function */
void MQTT_Publish(char *topic, char *payload)
{
    /*
      Replace this with actual MQTT middleware publish API.

      Example:
      mqtt_publish(topic, payload);

      For demo:
      sending publish message to UART.
    */

    char mqttMsg[200];

    sprintf(mqttMsg,
            "MQTT Topic: %s\r\nPayload: %s\r\n\r\n",
            topic,
            payload);

    HAL_UART_Transmit(&huart2,
                      (uint8_t*)mqttMsg,
                      strlen(mqttMsg),
                      HAL_MAX_DELAY);
}

/* USER CODE END 0 */

int main(void)
{

  /* MCU Configuration */

  HAL_Init();

  SystemClock_Config();

  MX_GPIO_Init();
  MX_USART2_UART_Init();
  MX_I2C1_Init();

  /* USER CODE BEGIN 2 */

  /* Sensor Initialization */

  BSP_HTS221_Init();

  BSP_LPS22HB_Init();

  sprintf(uartBuffer,
          "Smart Sensor Node Started\r\n\r\n");

  HAL_UART_Transmit(&huart2,
                    (uint8_t*)uartBuffer,
                    strlen(uartBuffer),
                    HAL_MAX_DELAY);

  /* USER CODE END 2 */

  /* Infinite loop */
  while (1)
  {

    /* USER CODE BEGIN WHILE */

    /* Read HTS221 Sensor */

    BSP_HTS221_GetTemperature(&temperature);

    BSP_HTS221_GetHumidity(&humidity);

    /* MQTT Payload */

    sprintf(mqttPayload,
            "{ \"temperature\": %.2f, \"humidity\": %.2f }",
            temperature,
            humidity);

    /* Publish MQTT Data */

    MQTT_Publish("stm32l475/sensor/data",
                 mqttPayload);

    /* Read Pressure Sensor */

    BSP_LPS22HB_GetPressure(&pressure);

    /* UART Output */

    sprintf(uartBuffer,
            "Pressure: %.2f hPa\r\n",
            pressure);

    HAL_UART_Transmit(&huart2,
                      (uint8_t*)uartBuffer,
                      strlen(uartBuffer),
                      HAL_MAX_DELAY);

    HAL_Delay(2000);

    /* USER CODE END WHILE */
  }
}

/**
  * @brief I2C1 Initialization Function
  */
static void MX_I2C1_Init(void)
{

  hi2c1.Instance = I2C1;
  hi2c1.Init.Timing = 0x10909CEC;
  hi2c1.Init.OwnAddress1 = 0;
  hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
  hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
  hi2c1.Init.OwnAddress2 = 0;
  hi2c1.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
  hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;

  if (HAL_I2C_Init(&hi2c1) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief USART2 Initialization Function
  */
static void MX_USART2_UART_Init(void)
{

  huart2.Instance = USART2;

  huart2.Init.BaudRate = 115200;

  huart2.Init.WordLength = UART_WORDLENGTH_8B;

  huart2.Init.StopBits = UART_STOPBITS_1;

  huart2.Init.Parity = UART_PARITY_NONE;

  huart2.Init.Mode = UART_MODE_TX_RX;

  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;

  huart2.Init.OverSampling = UART_OVERSAMPLING_16;

  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;

  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;

  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief GPIO Initialization Function
  */
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)
  {
  }
}