What External Examiners Actually Look For
In university final year viva examinations, examiners from other institutions are tasked with identifying whether the student batch understands the underlying hardware or is merely reciting memorized slides.
They will rarely ask high-level theoretical questions. Instead, they point directly at a component on your breadboard or perf-board and ask: "Why is this resistor placed here?", "What happens if this wire is unplugged?", or "What is the peak current consumption of this regulator?"
Mastering these practical details is what separates average marks from university project honors.
Circuit & Power Architecture Questions
Be ready to answer these foundational circuit questions:
1. "Why did you use pull-up resistors on the I2C bus?" -> Answer: "I2C SDA and SCL lines are open-drain. Without 4.7kΩ pull-up resistors to 3.3V, the lines cannot return to a logic HIGH state when released, resulting in bus hangs."
2. "What is the efficiency of your voltage regulator?" -> Answer: "Linear regulators like the LM7805 or AMS1117 dissipate excess voltage as heat (efficiency = Vout / Vin, barely 40% on a 12V supply). That is why we used a switched-mode DC-DC buck converter operating at over 88% efficiency."
3. "How did you prevent ground loops?" -> Answer: "We tied all return paths to a single star ground point at the negative battery terminal, preventing motor return spikes from fluctuating sensor reference grounds."
Firmware & Protocol Questions
Be ready to explain your microcontroller code logic:
1. "Why did you avoid using delay() in your code?" -> Answer: "delay() is a blocking function that halts the CPU instruction pointer, preventing timely servicing of sensor interrupts and network packets. We use non-blocking millis() timestamp comparisons and FreeRTOS task delays."
2. "What happens if the Wi-Fi or internet connection disconnects?" -> Answer: "Our firmware includes an offline state machine: sensor readings are buffered to local flash memory / SD card, and the ESP32 broadcasts a local fallback Wi-Fi hotspot so the dashboard remains functional."
3. "What communication baud rate did you choose and why?" -> Answer: "We selected 115200 baud for UART communication to ensure high-throughput sensor telemetry without introducing frame drops or buffer overflows."
Live Demonstration & Failure Recovery
During the live demonstration, examiners intentionally test boundary conditions. If your project experiences a glitch, do not panic. Examiners respect calm, systematic debugging far more than a lucky demo.
If a sensor freezes, state: "The I2C bus experienced a transient timeout. Our firmware watchdog will auto-recover the peripheral within 2 seconds." Then show the serial monitor output confirming recovery.
The Live Demo Emergency Survival Kit
Never show up to college review day without these 5 emergency backup tools:
• Digital Multimeter (DMM) for instant voltage rail checking.
• Spare pre-charged 18650 Li-ion battery pack with DC barrel jack.
• USB-C data cables (verify they are data-capable, not charging-only!).
• Dedicated mobile phone configured as a portable Wi-Fi hotspot matching your code SSID and password.
• Laminated A4 circuit schematic diagram placed on the desk beside your hardware prototype.