Schematic Capture in EasyEDA Pro: Libraries, Sheets, and ERC

Starting a New Schematic in the Project

EasyEDA Pro schematic capture flow: creating a schematic sheet, placing LCSC parts, wiring nets and power flags, hierarchical sheets, annotation, ERC, then Update PCB

In EasyEDA Pro, a schematic is always part of a project that also holds the PCB and any linked libraries. This second lesson in the series walks you through schematic capture: placing parts from the LCSC library, wiring up nets, splitting complex designs across hierarchical sheets, and running an ERC (Electrical Rule Check) before moving to the board.

When you open the project, a single schematic sheet is ready. The canvas is covered by a dotted grid that keeps components and wires aligned — connections only snap at grid points.

Sheet size: Set the page size (e.g. A4 or A3) in the sheet properties, with a title block for the design name, revision, and date.
Zoom and pan: Scroll wheel to zoom, press-and-drag the wheel to pan.
Saving: The project saves to the cloud (your EasyEDA account) or locally.

Tip: Name the project and sheet clearly from the start (e.g. PSU_24V_Controller). Random names become chaos once you have multiple sheets and revisions.

Placing Parts from the Library and LCSC

Parts are the heart of any schematic. In EasyEDA Pro the component library draws from three sources that all surface through one search panel:

Source	Contents	When to use
System library	Generic symbols: resistors, capacitors, connectors, power symbols	Standard symbols, early design
LCSC catalog	Hundreds of thousands of real parts with part number, price, and stock	Choosing a buyable physical part
Personal library	Symbols and footprints you created or edited	Company-specific parts

Searching the LCSC catalog

Open the library/search panel and type a part number directly (e.g. STM32F103C8T6), or search by spec (e.g. a 0603 resistor at 10k). Results arrive with symbol, footprint, and 3D model already attached — this direct link to the LCSC store removes the need to draw symbols by hand.

The JLCPCB-Assembled filter

When you inspect a part, note how it is classified for automated assembly at JLCPCB:

Basic: Low-cost staple parts always loaded on the assembly lines — no extra loading fee.
Extended: Expanded parts that usually require an extra feeder loading charge.

Prefer Basic parts when you plan to order an assembled board — it lowers cost and speeds up manufacturing.

After placing the symbol, set its value (e.g. 10kΩ or 100nF) and confirm the correct footprint is linked.

Wiring, Nets, and Power Flags

Components alone do not make a circuit — wiring turns them into nets. You draw a wire from one pin to another, and a junction dot appears wherever two wires truly connect. Beware: two wires crossing without a junction are not touching.

Net labels and grouping

In large circuits, dragging a wire between two far-apart pins gets messy. The fix is a net label: give two wires the same name (e.g. SPI_MOSI) and the software treats them as electrically connected without any visible line.

Power ports: Use GND and VCC/+3V3 symbols instead of hand-routing supply lines — every matching GND symbol automatically belongs to the same net.
Net classes: Group similar nets into one class (e.g. high-current power lines) so you can later apply trace-width rules on the board.

Name nets clearly and descriptively (USB_DP, MOTOR_PWM, ADC_IN1). Good names document the circuit and make fault-tracing far easier months later.

Hierarchical Sheets for Complex Designs

When a design grows — an MCU, power supply, motors, and comms — cramming it onto one crowded page is a mistake. This is where multi-sheet and hierarchical sheet design come in.

The idea is to split the design into functional blocks, one block per sheet:

A Power Supply sheet.
An MCU sheet.
A Communications sheet (USB / CAN / Ethernet).
A Motors or Sensors sheet.

In the hierarchical style, each child sheet is a sheet symbol on the parent page, with ports that wire it into the rest of the design — like building a circuit out of understandable "black boxes."

Approach	Benefit	Suited to
Single sheet	Simple and fast	Small circuits
Multiple flat sheets	Visual organization	Medium boards
Hierarchical blocks	Logical split and reuse	Large, complex boards

A major advantage is block reuse: a power block you designed and verified can be copied straight into a new project instead of being redrawn.

Annotation, Values, and Design Notes

Before a schematic is board-ready, every component must be clearly identified. That is the job of annotation — giving each part a unique designator:

R1, R2, R3 for resistors.
C1, C5 for capacitors.
U1, U3 for integrated circuits.
J1 for connectors, Q1 for transistors, D1 for diodes.

EasyEDA Pro can annotate automatically, but review the result and confirm no designator is duplicated — two identical designators confuse both the bill of materials (BOM) and the board.

Values, footprints, and notes

Value: The visible electrical value (4.7µF, 1MΩ).
Footprint: A correct footprint must be assigned to every part, or the transfer to the board fails.
On-sheet notes: Add text documenting design decisions ("max load current 2A", "resistor trimmed during calibration"). These notes rescue whoever services the board after you — including you, six months later.

Document the "why," not just the "what." The drawing shows what is connected; the note explains why this value was chosen.

Running the Electrical Rule Check (ERC)

Before touching the board, run the ERC (Electrical Rule Check). It reads the schematic automatically and catches common electrical errors that are hard to spot by eye:

Floating / unconnected pins: A pin left dangling with no net.
Conflicting outputs: Two push-pull outputs tied to one net — a potential short.
Missing power: A power net with no source feeding it.
Direction conflicts between input and output pins, based on each pin type.

The tool lists errors and warnings, and clicking any item jumps you straight to its location on the schematic. The golden rule: do not move to the board while red ERC errors you do not understand remain.

Distinguish an Error from a Warning. Some warnings are intentional (e.g. a deliberately floating test pin) and can be dismissed knowingly — but never ignore a red error without understanding it.

Preparing for the Board: Update PCB

Once ERC is clean, the bridge to the next stage is the Update PCB / Convert to PCB command. It takes the netlist from the schematic and pushes it into the board file.

What carries over?

From the schematic	To the board
Each part with its designator	Its physical footprint
Each net	A ratsnest line linking the pins that must connect
Net classes	Trace-width rules for later

The most powerful follow-up tool is cross-probing: selecting a part or net in the schematic highlights it on the board and vice versa, making it easy to trace the design across both worlds.

Repeat the "edit schematic → Update PCB" cycle on every change. Do not edit connectivity directly on the board — the schematic is the source of truth for the circuit.

Summary

In this lesson we built the schematic in EasyEDA Pro from scratch:

The schematic lives inside a project that holds the board and libraries; start with a well-named, organized sheet.
Place parts from the LCSC library by part number or spec, preferring Basic JLCPCB-assemblable parts.
Wire with net labels and power ports, and name your nets clearly.
For large designs, use hierarchical sheets and reusable blocks.
Annotate designators, assign values and footprints, and document decisions with notes.
Run the ERC and fix errors before anything else.
Finally run Update PCB to push the netlist, using cross-probing to stay in sync.

The next lesson moves to the most hands-on stage: PCB layout — arranging components, routing traces, and turning these nets into real copper.