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Tutorials

ESP32 PCB Layout and Routing

Overview​

This tutorial builds a minimal ESP32 development board — the kind you would order from JLCPCB and actually flash with firmware. It covers the three layers of every microcontroller design: the radio module, the glue components (strapping buttons, decoupling capacitor, status LED), and the routing that connects them.

You will place a real ESP32-C3-WROOM-02 module, wire the boot and enable strapping buttons, attach an indicator LED through a series resistor, then route the board with tscircuit's built-in autorouter.

What You Will Learn​

  • Placing an ESP32 module fetched from the tscircuit registry
  • The strapping pins (EN, IO0) every ESP32 bootloader needs
  • Why decoupling capacitors have a placement rule (and how tscircuit enforces it)
  • Choosing effort levels for hard autoroutes
  • Reading the preview to confirm every net is routed

The Module​

The heart of the board is the module. Instead of hand-drawing an ESP32 footprint, pull one from the registry — ESP32_C3_WROOM_02_N4 ships with correct pads, castellated edges, the antenna keep-out, and named pins (3V3, EN, IO0–IO9, GND, and more):

The antenna keep-out (marked on the module's silkscreen) must stay clear of copper — one more reason to use the registry module instead of a generic chip.

The Strapping Buttons​

Two pins decide how an ESP32 boots:

  • EN — system enable. Pull it low to reset the chip.
  • IO0 — bootloader strap. Hold it low while releasing EN and the chip enters the serial bootloader.

Both are just tactile buttons wired to ground:

SW1 is "reset", SW2 is "boot". On a real board you would also add 10k pull-ups on EN and IO0 so the module boots normally without buttons pressed.

The Status LED​

A classic debug heartbeat: a GPIO driving an LED through a current-limiting resistor. IO9 doubles as a boot-strap pin on the C3, which makes it the usual heartbeat choice:

The Decoupling Capacitor Rule​

Every ESP32 module needs a bulk capacitor between 3V3 and GND. tscircuit enforces a real design rule here: when a capacitor sits in a power-to-ground topology, it inherits a 1 mm maximum trace length (a decoupling cap must sit next to the pins it decouples — a cap 20 mm away is decoration, not decoupling).

The placement error tells you when a route cannot satisfy that length. You fix it by moving the capacitor close, or by relaxing the rule for a bulk cap that intentionally sits farther away:

For a tight decoupling cap, delete the maxDecouplingTraceLength prop and place the capacitor within 1 mm of the 3V3 pin.

The Whole Board​

Everything together — module, two strapping buttons, LED with resistor, bulk capacitor — routed automatically:

Notice autorouterEffortLevel="10x" on the board: the module brings 27 pads onto a small board and the router needs the extra compute to finish every net. Use 1x while iterating on placement, then raise the effort for the final route.

What You Learned​

  • ESP32 modules come from the registry with correct footprints and named pins — never draw a module footprint by hand.
  • EN and IO0 are the strapping pins your bootloader buttons attach to.
  • Decoupling capacitors carry a 1 mm placement rule that tscircuit enforces as a design rule; relax it explicitly (or move the cap) when it is a bulk cap.
  • autorouterEffortLevel trades compute time for route completeness on dense boards.
  • Zero render errors + every net in the connectivity map = a board ready for the ordering step.

Ordering the PCB​

Press the tscircuit "One-click order PCB" flow in the editor, or export gerbers for JLCPCB. The ESP32-C3-WROOM-02 module solders to the castellated pads by hand or with a stencil — no hot air required for a two-layer build.