Agricultural Monitoring System

Overview

A complete IoT pipeline for agricultural field monitoring, from raw sensor data on an STM32 microcontroller, through an MQTT broker, to a real-time web dashboard.

The system monitors soil moisture, ambient temperature, and humidity, triggering alerts when values cross configurable thresholds.

Architecture

[STM32 + Sensors] → UART → [ESP8266 Wi-Fi] → MQTT → [Broker]
                                                          ↓
                                               [Python FastAPI]
                                                          ↓
                                               [InfluxDB] → [Dashboard]

Embedded Layer

The STM32 firmware reads sensors via ADC and I2C, packages readings into a JSON string, and sends them over UART to the ESP8266 co-processor every 5 seconds.

#include "stm32f1xx_hal.h"
#include "dht22.h"

typedef struct {
    float temperature;
    float humidity;
    uint16_t soil_moisture_raw;
} SensorData;

HAL_StatusTypeDef read_sensors(SensorData *data) {
    /* Read DHT22 over bit-bang GPIO */
    if (DHT22_Read(&data->temperature, &data->humidity) != DHT22_OK) {
        return HAL_ERROR;
    }
    /* Read soil moisture via ADC channel 0 */
    HAL_ADC_Start(&hadc1);
    if (HAL_ADC_PollForConversion(&hadc1, 10) == HAL_OK) {
        data->soil_moisture_raw = HAL_ADC_GetValue(&hadc1);
    }
    HAL_ADC_Stop(&hadc1);
    return HAL_OK;
}

IoT Widget: Live Readout

Backend

A Python FastAPI service subscribes to the MQTT broker, validates incoming payloads, and writes time-series data to InfluxDB. Grafana provides the default dashboard: a custom lightweight web frontend was also built for mobile-friendly field access.