ESP32 Module Schematic
Overview
This tutorial builds a schematic-only ESP32-WROOM style module circuit. It keeps the example focused on the connections that matter before PCB layout:
- a 3.3 V regulator from USB 5 V
- EN reset and IO0 boot strapping
- USB-UART programming connections
- decoupling capacitors near the ESP32 module
- I2C, SPI, UART, power, and ground breakout headers
Use this as a starting point when you want an ESP32 module design that is easier to review before you add the final PCB footprint, antenna keepout, and routing.
Schematic
PCB Layout and Routing
Once the schematic nets are correct, move the ESP32 module to the edge of the board before placing the rest of the circuit. The example below keeps the USB-C connector and regulator on the left, puts the USB-UART bridge away from the antenna side, and fans the expansion headers out along the right edge.
Use the preview as a placement topology, then replace the placeholder
pinrow38 module footprint with the exact imported ESP32 module footprint you
plan to assemble. The important layout decisions are:
| Area | PCB layout and routing guidance |
|---|---|
| Antenna | Place the module so the antenna end is at the board edge. If the antenna cannot hang over the edge, keep the antenna area free of copper, routes, and components. |
| Power | Route 3.3 V from the regulator to the ESP32 as a short, wide path, then place the 10 uF and 100 nF capacitors next to the module supply pins. |
| Ground | Use a continuous ground plane under the module body, regulator, USB-UART bridge, and decoupling capacitors. Stitch ground near the module and around higher-speed routes. |
| USB | Keep D+ and D- together from the USB-C connector to the USB-UART bridge, and keep them away from the ESP32 antenna area. |
| UART | Keep U0TXD and U0RXD short between the USB-UART bridge and the ESP32, then route them away from the RF side of the module. |
| Headers | Fan out slower I2C and SPI breakout signals to board-edge headers after the local power, reset, boot, and USB programming circuits are placed. |
The Espressif ESP32 PCB layout guide is the design reference for antenna placement, 3.3 V trace width, ground-plane continuity, and keeping USB/UART routes away from the RF area.
Pin Groups
| Group | ESP32 pins used in the example | Purpose |
|---|---|---|
| Power | 3V3, GND1, GND2, GND3 | Main ESP32 supply and return pins. |
| Reset | EN | Pulled up to 3.3 V, with a reset button and capacitor to ground. |
| Boot | GPIO0 | Pulled up to 3.3 V, with a boot button to ground for programming mode. |
| USB-UART | U0TXD, U0RXD | Connects the ESP32 serial console and flashing interface to the USB-UART bridge. |
| I2C | GPIO21, GPIO22 | Breaks out the usual SDA and SCL pins for sensors. |
| SPI | GPIO23, GPIO19, GPIO18, GPIO5 | Breaks out MOSI, MISO, SCK, and CS for SPI peripherals. |
Adapting This for a Real PCB
Before turning this schematic into a routed board, confirm the exact ESP32 module variant and its datasheet. The common review points are:
- keep the antenna end of the module clear of copper, components, and ground pour according to the module datasheet
- keep the 10 uF and 100 nF 3.3 V capacitors close to the ESP32 module supply pins
- verify boot strapping pins before adding external pullups, pulldowns, or peripherals
- choose a 3.3 V regulator that can handle Wi-Fi transmit current peaks
- cross TX and RX between the USB-UART bridge and the ESP32 module