Communication Interfaces

UART, RS-232/485, SPI, I²C, CAN, LIN and Ethernet. Every bus an embedded engineer meets: an overview of protocols, UART with RS-232 and RS-485, SPI, I²C, CAN and LIN vehicle buses, and embedded Ethernet with TCP/IP.

• Communication Protocols Overview — Embedded devices talk over serial buses. Learn UART framing and baud rate, SPI modes, I²C addressing and pull-ups, CAN arbitration, RS-485 and Modbus, and how to choose the right protocol for each job.
• UART, RS-232 & RS-485 — The UART is the simplest and most universal serial interface — used for debug consoles, GPS modules, Bluetooth/Wi-Fi modems and industrial Modbus networks. Learn asynchronous framing (start, data, parity, stop), baud-rate generation and error, oversampling, flow control, error flags, DMA/interrupt reception, and the physical layers RS-232 (point-to-point, ±V levels) and RS-485 (differential, multi-drop, long distance).
• SPI — Serial Peripheral Interface — SPI is the fast, full-duplex synchronous bus used for Flash memories, displays, ADCs, SD cards and radios. Learn the four signals (SCLK, MOSI, MISO, CS), master/slave roles, the four clock modes (CPOL/CPHA), full-duplex shifting, chip-select handling, daisy-chaining, DMA transfers, Quad-SPI, signal-integrity limits and a real Flash-memory transaction.
• I²C — Inter-Integrated Circuit Bus — I²C connects many sensors, EEPROMs, RTCs and power ICs using just two wires. Learn open-drain signalling and pull-ups, start/stop conditions, 7-bit addressing, ACK/NACK, register read/write sequences with repeated start, clock stretching, speed modes, pull-up resistor sizing from bus capacitance, multi-master arbitration and bus-recovery techniques.
• CAN Bus — Controller Area Network is the backbone of in-vehicle communication. Learn the differential bus and termination, frame format (identifier, DLC, data, CRC, ACK), arbitration by priority, bit timing, error handling and bus-off, bus-load calculation, DBC signal databases and CAN FD.
• LIN Bus — Local Interconnect Network is a low-cost, single-wire bus for simple sensors and actuators. Learn master/slave (commander/responder) operation, the frame (break, sync, protected ID, data, checksum), schedule tables, timing, LDF files and diagnostics.
• Embedded Ethernet & TCP/IP — Ethernet brings embedded devices onto IP networks for industrial control, IoT gateways and cameras. Learn the MAC/PHY split and RMII/MII, frame structure and overheads, the TCP/IP stack layers, lightweight stacks (lwIP), DMA descriptor rings, UDP vs TCP trade-offs, sockets and raw APIs, industrial Ethernet protocols, security, and how to compute real throughput.