Introduction to IoT
Unit 3: Serial Communication & Bluetooth
From UART handshakes to wireless Bluetooth links — master the protocols that let your IoT devices talk to the world.
⏱️ Time to Complete: 8–10 hours | 💰 Earning Potential: ₹4,000–₹12,000/project | 📝 30 MCQs (Bloom's Mapped)
💼 Jobs this unlocks: Embedded Systems Intern (₹3–5 LPA) | IoT Developer (₹4–8 LPA) | Automation Engineer (₹5–10 LPA)
Opening Hook — When Machines Learn to Talk
🏭 How India's Smart Factories Run on Serial Protocols
Walk into Maruti Suzuki's Gurugram plant and you'll see hundreds of robotic arms welding, painting, and assembling cars — all coordinated by serial communication. Every sensor on the assembly line sends temperature, pressure, and vibration data over UART, SPI, and I2C buses to central PLCs (Programmable Logic Controllers) at speeds up to 10 Mbps. A single car's production involves over 4,000 serial data exchanges between microcontrollers.
Meanwhile, in Bengaluru, a startup called Stellapps is revolutionising India's dairy industry. Their IoT devices clipped onto cows use Bluetooth (HC-05/BLE) to transmit health vitals — body temperature, milk yield, activity patterns — to a farmer's smartphone. Over 7 million litres of milk are tracked daily across 30,000+ farms using these serial and wireless communication protocols.
What if YOU built this? What if you could make an Arduino read a temperature sensor over I2C, display values on your Serial Monitor, and send alerts to your phone over Bluetooth — all with code you wrote yourself? That's exactly what this chapter teaches you.
Learning Outcomes — Bloom's Taxonomy Mapped
| Bloom's Level | Learning Outcome |
|---|---|
| 🔵 Remember | Define UART, SPI, and I2C protocols and list their key signal lines (TX/RX, MOSI/MISO/SCK/SS, SDA/SCL) |
| 🔵 Understand | Explain the difference between serial and parallel communication, and why serial is preferred in embedded systems |
| 🟢 Apply | Write Arduino code using Serial.begin(), Serial.print(), Serial.read() to send/receive data via the Serial Monitor |
| 🟢 Analyze | Compare SPI, I2C, and UART across speed, wiring complexity, device count, and use cases, selecting the right protocol for a given scenario |
| 🟠 Evaluate | Assess the HC-05 Bluetooth module's capabilities and limitations for IoT projects, including range, pairing security, and data rates |
| 🟠 Create | Build a complete Bluetooth-controlled LED project: wire HC-05 to Arduino, write Arduino code, and control from a smartphone app |