The physical design of an IoT system refers to the individual node devices and their protocols utilized to create a functional IoT ecosystem. Each node device can perform tasks such as remote sensing, actuating, and monitoring by relying on physically connected devices. These devices are also capable of transmitting information through various types of wireless or wired connections.

Functions of IoT Devices

The devices in an IoT system serve multiple purposes, including:

• Building Connections: Establishing communication between devices and the server.
• Data Processing: Collecting and processing data from the environment.
• Providing Storage: Storing generated data for future analysis.
• Providing Interfaces: Offering input/output interfaces for interaction.
• Providing Graphical Interfaces: Enabling visual representation of data for users.

For example, a moisture sensor collects data from a location, and the system analyzes this data to provide actionable outputs. Similarly, temperature sensors generate data that algorithms process to improve decision-making.

Components of IoT Devices

1. Connectivity:
   • Devices like USB hosts and Ethernet are used to establish connectivity between devices and servers.
2. Processor:
   • A processor (e.g., CPU) processes data, which is then used to enhance the decision quality of an IoT system.
3. Audio/Video Interfaces:
   • Interfaces like HDMI and RCA devices record and manage audio and video data.
4. Input/Output Interfaces:
   • Interfaces such as UART, SPI, and CAN provide input and output signals for sensors and actuators.
5. Storage Interfaces:
   • Devices like SD, MMC, and SDIO store the data generated by IoT devices.
6. Other Components:
   • DDR and GPUs are used to control and enhance IoT system activities.

IoT Protocols

IoT protocols enable communication between node devices and servers over the internet. They facilitate the sending of commands to IoT devices and the receipt of data from them. These protocols are structured across network layers, including application, transport, network, and link layers.

Application Layer Protocols

This layer defines how data can be sent over the network using lower-layer protocols through the application interface. Key protocols include:

• HTTP: Hypertext Transfer Protocol facilitates the transmission of media documents between web browsers and servers. It operates as a request-response model without maintaining session states.
• WebSocket: Enables two-way communication between a client and a host, often used by web browsers.
• MQTT: A machine-to-machine connectivity protocol designed for remote locations with small code footprints, using a publish/subscribe model.

Transport Layer Protocols

This layer controls the flow of data segments and handles error control, providing end-to-end message transfer capabilities. Key protocols include:

• TCP (Transmission Control Protocol): Ensures reliable data exchange by establishing and maintaining a connection.
• UDP (User Datagram Protocol): A connectionless protocol for fast, low-latency data transfer without the need to establish a connection.

Network Layer Protocols

This layer is responsible for transferring data packets from source to destination. Key protocols include:

• IPv4: A 32-bit protocol address used for host and location addressing in networks.
• IPv6: A 128-bit successor to IPv4, developed to address scalability and long-term networking needs.

Link Layer Protocols

Link-layer protocols manage the transmission of data over a network’s physical layer, determining how packets are coded and signaled. Key protocols include:

• Ethernet: Defines the physical layer and media access control for wired LAN networks.
• Wi-Fi: Specifies media access control and physical layer protocols for wireless LANs.

Conclusion

The physical design of an IoT system is a combination of hardware components and communication protocols that enable connectivity, data processing, and interaction between devices. IoT devices generate data that is analyzed to improve system operations, while protocols ensure seamless communication across network layers. Together, these elements form the foundation of an efficient and functional IoT ecosystem.