Communication Protocols

Communication Protocols

Use this page to revise how chips and systems exchange bytes.

On-board serial

• UART: asynchronous, two data wires plus GND, agreed baud rate.
• SPI: synchronous, clock + MOSI/MISO + chip-select; fast, short, one master.
• I²C: two wires (SDA, SCL) with pull-ups, addresses, ACK/NACK; several devices on one bus.

Networks and IoT messaging

IP (TCP vs. UDP) is how larger devices talk. MQTT is a publish/subscribe protocol over TCP (usually) with topics, a broker, and QoS levels. BLE and Wi-Fi are radios with very different range, power, and pairing models.

What a protocol is not

A wiring picture is not a protocol. Timing, voltage, who is master, and error handling are.

Starting Points

• Serial protocols
• Connectivity & IoT
• MQTT.org. MQTT.

Key Points

• You can contrast UART, SPI, and I²C (wires, clock, addressing, typical use).
• You can explain why I²C needs pull-ups and a common ground.
• You can explain TCP vs. UDP in one sentence each.
• You can explain MQTT broker, topic, and why QoS is not "the network is safe".
• You can name one reason to pick BLE vs. Wi-Fi for a battery device.