ESP32 Microcontroller: A Review of Architecture, Communication Protocols, Applications and Research Challenges

The rapid expansion of the Internet of Things (IoT) has increased the demand for low-cost, high-performance, and energy-efficient microcontrollers with integrated wireless communication capabilities. Among the available platforms, the ESP32 microcontroller has emerged as a widely adopted solution for IoT and embedded system applications due to its dual-core processing architecture, built-in Wi-Fi and Bluetooth connectivity, rich peripheral support, and flexible software ecosystem. This paper presents a comprehensive review of the ESP32 microcontroller, focusing on its hardware architecture, supported communication protocols, development frameworks, and application domains. The study systematically examines the use of ESP32 in diverse areas such as smart agriculture, healthcare and wearable systems, smart city infrastructure, industrial IoT, and environmental monitoring. In addition, a comparative analysis with other commonly used microcontrollers is provided to highlight the strengths and limitations of ESP32-based systems. Key research challenges related to power consumption, security, scalability, real-time performance, and memory constraints are critically discussed. Finally, future research directions are outlined, emphasizing opportunities in edge intelligence, hybrid communication architectures, energy-efficient designs, and secure IoT deployments. This review aims to serve as a valuable reference for researchers and practitioners in selecting, designing, and optimizing ESP32-based solutions for modern IoT applications.