Core Protocols in Embedded Systems

The Core Embedded System Protocols

These protocols dictate how microcontrollers, sensors, and computers talk to one another.

How it works: One of the oldest and simplest methods. It uses just two wires (one to send, one to receive).
Timing: Asynchronous. There is no shared clock. Instead, both devices must agree on a specific speed (baud rate) before they start talking—like two people agreeing to speak at the same pace.
Where you will find it: Arduino boards, GPS modules, and Bluetooth adapters. It is not the fastest, but its simplicity keeps it everywhere.

How it works: Faster than UART, SPI uses four wires: Clock, MOSI (Master Out Slave In), MISO (Master In Slave Out), and Chip Select.
Timing: Synchronous. The Clock wire acts like a conductor leading an orchestra, keeping the Master device and all Slave devices perfectly in sync.
Where you will find it: SD cards, display screens, and flash memory. It is incredibly fast, but the 4-wire requirement can get messy if you connect too many devices.

How it works: The smart middle ground. It uses only two wires (Data and Clock) but can connect up to 127 different devices.
Addressing: Each device gets a unique address. It acts like a group chat where everyone is on the same line, but a device only responds when the Master calls its specific name.
Where you will find it: Temperature sensors, OLED displays, and gyroscopes. It saves wiring space compared to SPI, though it operates at a slower speed.

How it works: Invented by Bosch in 1983 specifically for cars. It allows dozens of computers (engine, brakes, airbags) to share just two wires (CAN High and CAN Low).
Conflict Resolution: If two devices talk at the exact same time, CAN has a built-in priority system to decide who goes first without losing any data.
Where you will find it: Every modern car, trucks, industrial robots, and medical equipment. It is heavily battle-tested for reliability.

How it works: Defined in 1960, this is a point-to-point protocol designed to fight electrical noise over long cables. Unlike standard logic (0 to 3.3V), RS-232 uses massive voltage swings (+15V to -15V).
Where you will find it: The old 9-pin DB9 connectors on vintage PCs. Today, it survives in industrial machines, factory equipment, and legacy point-of-sale terminals.

How it works: As the name implies, it uses a single wire for both data communication and power. Devices come from the factory with a unique burned-in 64-bit ID.
Where you will find it: The famous DS18B20 temperature sensor, laptop battery fuel gauges, and iButton security keys. It is very slow, but unbeatable when you absolutely must minimize wiring.

Click to reveal protocol explorer