Quick Start

This guide will get you up and running with Circuit-Synth in just a few minutes!

Note

New to Circuit-Synth? This page shows you how to create your first circuit in under 5 minutes. For more complex examples, see our Examples page.

Basic LED Circuit Example

Let’s start with a simple LED circuit that demonstrates the core concepts:

     3.3V ──┬── R1 (330Ω) ──┬── D1 (LED) ── GND
            │                │
            └── Power Input  └── Current Limiting

Here’s how to implement this circuit in Circuit-Synth:

from circuit_synth import Circuit, Component, Net, circuit

@circuit(name="simple_led")
def simple_led():
    """
    Simple LED circuit with current limiting resistor.
    Perfect for getting started with Circuit-Synth!
    """

    # Create power nets
    VCC_3V3 = Net('VCC_3V3')
    GND = Net('GND')

    # Create LED component
    led = Component(
        symbol="Device:LED",
        ref="D",
        value="Red",
        footprint="LED_SMD:LED_0603_1608Metric"
    )

    # Create current limiting resistor
    resistor = Component(
        symbol="Device:R",
        ref="R",
        value="330",
        footprint="Resistor_SMD:R_0603_1608Metric"
    )

    # Make connections
    VCC_3V3 += resistor[1]     # Power to resistor
    resistor[2] += led[1]      # Resistor to LED anode
    led[2] += GND              # LED cathode to ground

# Generate KiCad files
if __name__ == '__main__':
    circuit = simple_led()
    circuit.generate_kicad_project("my_first_circuit")
    print("Circuit generated! Check the 'my_first_circuit' folder.")

Core Concepts

Components

Components are the building blocks of your circuits. Each component needs four key properties:

Component Structure:
symbol: KiCad library symbol
ref: Reference prefix (R, C, U, etc.)
value: Component value/name
footprint: Physical package for PCB

# Standard 10kΩ resistor (0603 package)
resistor = Component(
    symbol="Device:R",              # KiCad symbol
    ref="R",                        # Reference prefix
    value="10K",                    # Resistance value
    footprint="Resistor_SMD:R_0603_1608Metric"  # Physical footprint
)

Nets

Nets represent electrical connections (wires) between components:

Tip: Use descriptive net names like 'VCC_3V3' instead of 'Net1'

# Power and ground nets
VCC_3V3 = Net('VCC_3V3')     # 3.3V power supply
VCC_5V = Net('VCC_5V')       # 5V power supply
GND = Net('GND')             # Ground reference

# Signal nets
SPI_MOSI = Net('SPI_MOSI')   # SPI data line
USB_DP = Net('USB_DP')       # USB D+ signal

Circuits

Use the @circuit decorator to define circuit functions:

@circuit
def my_circuit():
    # Define your circuit here
    pass

Pin Connections

Connect component pins to nets using indexing:

# Connect pin 1 of resistor to power net
resistor[1] += power_net

# Connect pin 2 of resistor to signal net
resistor[2] += signal_net

Hierarchical Design

Circuit-Synth excels at building complex systems from reusable building blocks:

Tip

Professional Practice: Keep one circuit per file for better organization and reusability.

# power_supply.py - Reusable 3.3V regulator
@circuit(name="ldo_3v3")
def ldo_3v3_regulator(vin, vout, gnd):
    """3.3V linear regulator with decoupling caps"""
    regulator = Component("Regulator_Linear:AMS1117-3.3", ref="U")
    # ... implementation details

# led_indicators.py - Reusable LED circuit
@circuit(name="status_led")
def status_led(vcc, gnd, control_signal):
    """LED with current limiting resistor"""
    # ... implementation details

# main_board.py - Complete system
@circuit(name="esp32_dev_board")
def esp32_development_board():
    """Complete ESP32 board with power and LEDs"""
    VIN_5V = Net('VIN_5V')
    VCC_3V3 = Net('VCC_3V3')
    GND = Net('GND')

    # Compose subsystems
    ldo_3v3_regulator(VIN_5V, VCC_3V3, GND)  # Power supply
    status_led(VCC_3V3, GND, esp32_gpio)     # Status indicator
    # ... ESP32 and other circuits

Hierarchical Project Structure:
├── components.py      # Reusable parts library
├── power_supply.py    # Voltage regulators
├── led_indicators.py  # Status LEDs
└── main_board.py      # System integration

Next Steps

Ready to dive deeper? Here’s your learning path:

What to explore next:

• Examples - Complete ESP32, STM32, and power supply projects

• API Reference - Comprehensive API documentation and advanced features

• contributing - Help make Circuit-Synth even better

• GitHub Issues - Report bugs or request features

Note

Stuck? Join our community discussions or file an issue on GitHub. We’re here to help you succeed with Circuit-Synth!