1. Introduction

This week’s group assignment consisted of learning how to use laboratory test equipment to observe and analyze the operation of a microcontroller circuit board.

As a minimum requirement, we demonstrated the use of:

• A Multimeter
• An Oscilloscope

The system under test was an ESP32-C3 development board powered via USB (5V) and operating at 3.3V logic level.

The objective was to understand how electrical signals behave in real hardware and to validate circuit functionality before moving into PCB design.

2. Definitions of Technical Equipment

3. Electrical Fundamentals

3.1 Ohm’s Law

Ohm’s Law relates voltage, current, and resistance:

V = I × R

Where:
V = Voltage (Volts)
I = Current (Amperes)
R = Resistance (Ohms)

Derived forms:
I = V / R
R = V / I

3.2 Electrical Power

Power is the rate at which electrical energy is consumed.

P = V × I

Alternative forms using Ohm’s Law:
P = I² × R
P = V² / R

Where:
P = Power (Watts)

Example – LED with ESP32-C3

ESP32-C3 GPIO = 3.3V
LED forward voltage ≈ 2.0V
Desired current = 5mA (0.005A)

R = (3.3V − 2.0V) / 0.005A
R = 260Ω

Standard value used: 220Ω

Power dissipation in resistor:
P = V × I
P = 1.3V × 0.005A
P = 0.0065W (6.5mW)

A 1/4W resistor is more than sufficient.

4. Using the Multimeter

4.1 Measuring Voltage

Purpose: Verify correct power supply levels.

1. Turn on multimeter.
2. Select DC Voltage (<20V range).
3. Connect black probe to GND.
4. Connect red probe to measurement point.

Measurements performed:
Working battery → 8.9V
Dead battery → 1.2V
ESP32-C3 3.3V output → 3.2V

This confirmed proper voltage regulation.

4.2 Measuring Resistance

Purpose: Confirm resistor value.

1. Power off circuit.
2. Select Ω mode.
3. Place probes across resistor terminals.

Measured value: 220Ω

4.3 Testing Continuity

Purpose: Ensure circuit connections are closed and solder joints are correct.

1. Turn off power.
2. Select continuity mode (beep symbol).
3. Touch probes across GND connections, LED terminals, PCB traces.

Beep indicates closed circuit.

4.4 Measuring Current

Purpose: Determine actual current consumption.

Current must be measured in series.

1. Disconnect power.
2. Open power line.
3. Set multimeter to DC mA mode.
4. Insert multimeter in series.
5. Reconnect power.

Measured value for blinking LED circuit: 5.4 mA

5. Using the Oscilloscope

5.1 Setup

1. Turn on oscilloscope.
2. Select DC coupling.
3. Adjust Voltage scale (Volts/div) and Time scale (Time/div).

Calibration was required to properly visualize the waveform.

5.2 Observing GPIO Blink Signal

The ESP32-C3 was programmed with a blinking LED (100 ms interval).

Probe connections:
Tip → GPIO pin
Ground clip → GND

Observed waveform:
Square wave
0V (LOW)
3.3V (HIGH)

5.3 Changing Frequency

LOW = 500 ms
HIGH = 100 ms

The waveform width changed accordingly, demonstrating duty cycle variation.

5.4 Observing Serial Communication

We transmitted character “K”. ASCII binary: 111101011

Oscilloscope displayed Start bit (0), Data bits, Stop bit (1).

This confirmed correct digital serial transmission.

6. Key Learning Outcomes

• How to safely use a multimeter.
• How to measure voltage, resistance, current, and continuity.
• How to validate power integrity in a microcontroller board.
• The difference between DC average measurement and time-based waveform visualization.
• How digital signals appear as square waves.
• How theoretical calculations compare to real measurements.

7. Conclusion

This group assignment provided practical experience using laboratory test equipment to analyze a microcontroller system. By validating electrical parameters on the ESP32-C3 board, we reinforced fundamental concepts such as Ohm’s Law, power dissipation, signal integrity, and digital waveform behavior.

These skills are essential for the upcoming PCB design and fabrication stages, where electrical validation becomes critical before hardware deployment.

INDIVIDUAL ASSIGNMENT – ELECTRONICS DESIGN

1. Introduction

For this assignment, I designed a custom electronic system using KiCad as the Electronic Design Automation (EDA) software. The project integrates a Seeed Studio XIAO ESP32-C3 microcontroller to control two servo motors.

The workflow included:

• Circuit design in KiCad
• Simulation in Wokwi
• Firmware development in Arduino IDE
• PCB layout generation
• Manufacturing-ready board design

2. About KiCad

KiCad is an open-source Electronic Design Automation (EDA) tool used to design schematics and printed circuit boards (PCBs).

It allows:

• Creation of schematic diagrams
• Assignment of footprints
• PCB layout design
• 3D visualization
• Generation of manufacturing files (Gerbers)

KiCad is widely used in academic and professional electronics development due to its flexibility and open-source ecosystem.

3. System Description

The system consists of:

• 1 XIAO ESP32-C3 microcontroller
• 2 Servo Motors (PWM controlled)
• External 5V power input
• Ground reference shared across system

The ESP32-C3 generates PWM signals to control both servos independently.

4. Circuit Simulation in Wokwi

Before designing the PCB, the system was simulated using Wokwi.

Steps:

1. Create new ESP32 project.
2. Select ESP32-C3 board.
3. Add two servo components.
4. Connect:
   • Servo 1 → GPIO D9
   • Servo 2 → GPIO D10
   • 5V external power
   • Common GND
5. Upload and test Arduino code.

Simulation verified PWM signal generation, correct servo positioning and proper logic levels (3.3V compatible).

5. Programming in Arduino IDE

After validating the simulation, the firmware was developed in Arduino IDE.

Steps:

1. Install ESP32 board support.
2. Open Preferences and add ESP32 board URL.
3. Install ESP32 board package.
4. Install ESP32Servo library.

The program controls two servos using PWM signals and predefined movement sequences.

6. Installing Fab Academy KiCad Library

To follow Fab Academy PCB standards, the Fab library was installed.

1. Download FabAcademy KiCad library files.
2. Preferences → Manage Symbol Libraries → Add Existing Library.
3. Select fab.kicad_sym.
4. Preferences → Manage Footprint Libraries → Add Existing Library.
5. Select fab.pretty folder.

This enables access to Fab-standard components such as resistors, capacitors, pin headers and microcontrollers.

7. Creating the Schematic

Open KiCad and create a new project.

Step 1: Add Components

• XIAO ESP32-C3
• 2 Servo connectors (3-pin headers)
• External 5V input connector
• Capacitor for filtering
• GND symbols
• Power symbols (5V)

Step 2: Connect the Circuit

• D9 → Servo1 Signal
• D10 → Servo2 Signal
• 5V external → Servo VCC
• GND → All GND pins connected

Step 3: Annotate

Tools → Annotate Schematic.

Step 4: Electrical Rules Check

Run ERC to detect unconnected pins, power issues and missing drivers.

8. Assigning Footprints

Open Tools → Assign Footprints.

• PinHeader_1x03 → Servo connectors
• PinHeader_1x07 → XIAO headers
• Capacitor_SMD → Filtering capacitor

Save and update PCB.

9. PCB Layout Design

Open PCB Editor.

Step 1: Define Board Outline

Use Edge.Cuts layer to draw rectangular board shape.

Step 2: Place Components

• XIAO centered
• Servo connectors at edge
• Power input accessible

10. Routing the PCB

• Signal width: 0.4mm
• Power traces: 0.6mm–0.8mm
• Keep traces short and clean
• Avoid sharp 90° angles

11. Ground Plane (Copper Fill)

1. Select Add Filled Zone
2. Choose F.Cu layer
3. Select GND net
4. Draw polygon around board
5. Press B to refill zones

Benefits include reduced noise, better current return path and improved EMI performance.

12. Design Rule Check (DRC)

Run DRC and inspect clearance violations, overlapping pads and unconnected nets.

13. 3D View and Final Inspection

Open 3D Viewer and verify component placement, connector orientation and mechanical fit.

14. Generating Manufacturing Files

• Generate Gerber Files
• Generate Drill Files
• Plot F.Cu, B.Cu, Edge.Cuts, F.SilkS, F.Mask

15. Final Board Description

The final PCB includes microcontroller interface for XIAO ESP32-C3, dual PWM output for servo motors, external 5V power supply, ground plane for signal stability and compact layout optimized for digital control applications.

16. Learning Outcomes

• Complete EDA workflow
• PCB routing strategy
• Power distribution design
• Importance of ground planes
• Integration between firmware and hardware
• Simulation before fabrication
• Professional documentation standards

17. Evidence and Image Upload

To include documentation images, upload your image inside the directory: