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309 changes: 309 additions & 0 deletions docs/tutorials/esp32-pcb-layout-routing.mdx
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---
title: ESP32 PCB Layout and Routing
description: Route a small ESP32-WROOM carrier board with tscircuit, including boot/reset passives, a programming header, antenna keepout, and ground pours.
---

import CircuitPreview from "@site/src/components/CircuitPreview";

## Overview

This tutorial starts from an ESP32 schematic-style connection list and turns it
into a practical PCB layout. The example board uses a simplified ESP32-WROOM
module footprint, a 6-pin programming header, boot and reset buttons, an
indicator LED, and ground pours on both copper layers.

The goal is not to copy every pin from a production ESP32 module. It is to show
the layout moves you make after the circuit is connected:

- put the module antenna at the board edge
- keep decoupling capacitors close to 3.3 V pins
- place boot and reset passives beside their ESP32 pins
- route UART and strap signals away from the antenna region
- pour ground after the critical component placement is stable

## Complete Board

<CircuitPreview
leftView="code"
rightView="pcb"
defaultView="pcb"
hide3DTab
showCourtyards
code={`
const esp32PinLabels = {
pin1: ["GND_1"],
pin2: ["3V3"],
pin3: ["EN"],
pin10: ["GPIO25"],
pin24: ["GPIO2"],
pin25: ["BOOT_IO0"],
pin29: ["GPIO5"],
pin34: ["RX0"],
pin35: ["TX0"],
pin36: ["GPIO22"],
pin37: ["GPIO23"],
pin38: ["GND_3"],
} as const

const Esp32WroomDemo = (props: {
name: string
pcbX?: number
pcbY?: number
schX?: number
schY?: number
}) => (

<chip
{...props}
pinLabels={esp32PinLabels}
schPortArrangement={{
leftSide: {
pins: ["3V3", "EN", "BOOT_IO0", "RX0", "TX0", "GND_1"],
direction: "top-to-bottom",
},
rightSide: {
pins: ["GPIO2", "GPIO5", "GPIO22", "GPIO23", "GPIO25", "GND_3"],
direction: "top-to-bottom",
},
}}
footprint={
<footprint>
<silkscreenrect pcbX={0} pcbY={0} width="18mm" height="25mm" />
<silkscreentext
text="ESP32-WROOM"
pcbX={0}
pcbY={0}
fontSize="1.1mm"
anchorAlignment="center"
/>
<smtpad
portHints={["pin1"]}
pcbX="-9.4mm"
pcbY="7.5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin2"]}
pcbX="-9.4mm"
pcbY="5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin3"]}
pcbX="-9.4mm"
pcbY="2.5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin10"]}
pcbX="-9.4mm"
pcbY="0mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin24"]}
pcbX="-9.4mm"
pcbY="-2.5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin25"]}
pcbX="-9.4mm"
pcbY="-5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin29"]}
pcbX="9.4mm"
pcbY="-5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin34"]}
pcbX="9.4mm"
pcbY="-2.5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin35"]}
pcbX="9.4mm"
pcbY="0mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin36"]}
pcbX="9.4mm"
pcbY="2.5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin37"]}
pcbX="9.4mm"
pcbY="5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
<smtpad
portHints={["pin38"]}
pcbX="9.4mm"
pcbY="7.5mm"
width="1.5mm"
height="0.9mm"
shape="rect"
/>
</footprint>
}
/>
)

export default () => (
<board width="44mm" height="54mm" autorouter="sequential-trace">
<Esp32WroomDemo name="U1" pcbX={0} pcbY={8} schX={0} schY={0} />

<pcbnoterect
pcbX={0}
pcbY={22}
width="22mm"
height="8mm"
color="#d97706"
strokeWidth={0.2}
isStrokeDashed
/>
<pcbnotetext
pcbX={0}
pcbY={22}
text="ANTENNA KEEPOUT"
fontSize={0.9}
color="#d97706"
anchorAlignment="center"
/>

<pinheader
name="J1"
pinCount={6}
pinLabels={{
pin1: "GND",
pin2: "3V3",
pin3: "TXD",
pin4: "RXD",
pin5: "EN",
pin6: "BOOT",
}}
pcbX={0}
pcbY={-20}
schX={-7}
schY={-6}
/>

<resistor name="R_EN" resistance="10k" footprint="0402" pcbX={-13} pcbY={8} schX={-5} schY={4} />
<pushbutton name="SW_RESET" footprint="pushbutton" pcbX={-17} pcbY={2} schX={-5} schY={1} />
<resistor name="R_BOOT" resistance="10k" footprint="0402" pcbX={-13} pcbY={-2} schX={-5} schY={-2} />
<pushbutton name="SW_BOOT" footprint="pushbutton" pcbX={-17} pcbY={-8} schX={-5} schY={-5} />

<capacitor name="C1" capacitance="100nF" footprint="0402" pcbX={-13} pcbY={14} schX={4} schY={3} />
<capacitor name="C2" capacitance="10uF" footprint="0603" pcbX={-16} pcbY={14} schX={4} schY={0} />

<resistor name="R_LED" resistance="1k" footprint="0402" pcbX={12} pcbY={-8} schX={5} schY={-3} />
<led name="D1" color="blue" footprint="0603" pcbX={16} pcbY={-8} schX={8} schY={-3} />

<trace from=".J1 > .pin1" to="net.GND" />
<trace from=".J1 > .pin2" to="net.V3_3" />
<trace from=".J1 > .pin3" to=".U1 > .RX0" />
<trace from=".J1 > .pin4" to=".U1 > .TX0" />
<trace from=".J1 > .pin5" to=".U1 > .EN" />
<trace from=".J1 > .pin6" to=".U1 > .BOOT_IO0" />

<trace from=".U1 > .3V3" to="net.V3_3" />
<trace from=".U1 > .GND_1" to="net.GND" />
<trace from=".U1 > .GND_3" to="net.GND" />
<trace from=".C1 > .pos" to="net.V3_3" />
<trace from=".C1 > .neg" to="net.GND" />
<trace from=".C2 > .pos" to="net.V3_3" />
<trace from=".C2 > .neg" to="net.GND" />

<trace from=".R_EN > .pos" to="net.V3_3" />
<trace from=".R_EN > .neg" to=".U1 > .EN" />
<trace from=".SW_RESET > .pin1" to=".U1 > .EN" />
<trace from=".SW_RESET > .pin2" to="net.GND" />

<trace from=".R_BOOT > .pos" to="net.V3_3" />
<trace from=".R_BOOT > .neg" to=".U1 > .BOOT_IO0" />
<trace from=".SW_BOOT > .pin1" to=".U1 > .BOOT_IO0" />
<trace from=".SW_BOOT > .pin2" to="net.GND" />

<trace from=".U1 > .GPIO2" to=".R_LED > .pos" />
<trace from=".R_LED > .neg" to=".D1 > .pos" />
<trace from=".D1 > .neg" to="net.GND" />

<copperpour connectsTo="net.GND" layer="top" clearance="0.25mm" />
<copperpour connectsTo="net.GND" layer="bottom" clearance="0.25mm" />

</board>
)
`}
/>

## Placement Strategy

Place the ESP32 module before the small parts. The antenna end should sit at the
edge of the PCB, with no copper, traces, headers, or mounting hardware under the
keepout rectangle. In the example, the dashed rectangle marks the space to keep
clear above the module.

After the module is locked in, place parts by electrical priority:

| Part | Placement rule |
| ------------------- | ---------------------------------------------------------------------------------------- |
| `C1`, `C2` | Put decoupling capacitors next to the 3.3 V and ground pads. |
| `R_EN`, `SW_RESET` | Keep the reset pullup and button near `EN`. |
| `R_BOOT`, `SW_BOOT` | Keep the boot pullup and button near `BOOT_IO0`. |
| `J1` | Put the programming header where a cable can reach it without crossing the antenna side. |
| `D1`, `R_LED` | Move optional indicators away from RF and boot/reset routing. |

## Routing Order

Route the board in this order:

1. Connect the local 3.3 V decoupling loop from `U1` to `C1` and `C2`.
2. Connect `EN` and `BOOT_IO0` to their pullups and buttons.
3. Route UART `TXD` and `RXD` from the header to the module.
4. Route optional GPIO signals such as the indicator LED.
5. Add the top and bottom ground pours after traces and placement are stable.

This keeps the short, sensitive power and strap nets from being pushed around by
less important routing. It also makes the remaining signals easier to inspect in
the PCB viewer.

## Adapting the Example

For a production design, replace the simplified `Esp32WroomDemo` footprint with
a verified footprint for the exact module variant. Keep the same layout
principles:

- preserve the antenna keepout from the module datasheet
- use one 100 nF capacitor per nearby power pin and add a local bulk capacitor
- keep reset and boot straps short and readable
- avoid routing high-speed or noisy traces under the antenna
- review the routed board in both PCB and schematic views before exporting
fabrication files
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