**Introduction**
Traditional agriculture has long relied on extensive manual labor, resulting in low productivity and inefficiency. As a result, there is an urgent need to transition toward modern agricultural practices. Greenhouse technology stands out as a key component of modern farming, enabling crops to grow independently from natural environmental conditions by creating a semi-closed system that can be manually controlled. Since the 1990s, China has been studying advanced greenhouse technologies from countries like the Netherlands and the United States. However, due to differences in local agricultural conditions, it is not feasible to directly adopt foreign models. Instead, a customized greenhouse control system tailored for China's diverse regional environments is essential.
To address these challenges, a remote monitoring and control system for greenhouses was developed. Among various environmental factors, air temperature and humidity play a critical role in crop growth, so the system focuses on monitoring and regulating these parameters. Traditional 51 series microcontroller units (MCUs) lack sufficient processing power and scalability, while PLC-based systems are too costly. Therefore, the STM32 MCU, known for its rich peripherals, strong expandability, and cost-effectiveness, was chosen as the core controller for this system.
**1. System Overall Design**
A greenhouse remote monitoring and control system based on the STM32 microcontroller was designed. By using the STM32 as the central controller and MFC-based remote control software, it becomes possible to monitor and manage temperature and humidity remotely. An ENC28J60 module was integrated into the STM32 design to enable network connectivity, and the LwIP protocol was implemented to allow communication with the remote control software via TCP/IP.
The STM32 controller directly interfaces with the DHT11 sensor and relay module. The DHT11 measures the temperature and humidity inside the greenhouse, while the relay module controls the heating and misting systems to regulate the internal environment. Using the VC6.0 platform, an intuitive remote control interface was developed with MFC, allowing users to monitor real-time data, control equipment, and store collected information in a database. As shown in Figure 1.
**Figure 1: System overall block diagram**
**2. System Hardware Design**
**2.1. Selection of the Core Processor**
The STM32 microcontroller offers a wide range of peripherals, including 64KB of static RAM and 512KB of flash memory. It features up to 112 GPIO pins, which can be configured in four different modes as needed. Additionally, it includes seven general-purpose DMA channels for efficient memory-to-memory and memory-to-peripheral data transfers. The STM32 also integrates three 12-bit ADCs, an I2C bus interface, two SPI buses for communication between master and slave devices, an external Ethernet interface, three USART ports, one SDIO interface for memory expansion, and a JTAG interface for debugging. These features make it an ideal choice for building a reliable and scalable greenhouse control system.
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