ESP8266 Arduino adapter

Adapter circuit to connect the ESP-01 to Arduino UART

ESP8266 Arduino adapter

This page explains how to build an adapter for the ESP-01 WiFi module to connect its UART to Arduino Serial.

Materials needed:
- ESP-01 WiFi module
- 8-pin socket for the ESP-01 module
- 1x 470R resistor
- 2x 220R resistors
- 2x 47uF capacitors
- 3.3V 250mA LDO voltage regulator MCP1702T3302ECB
- 2-pin jumper + jumper header
- wires
- protoboard
- soldering iron + solder

Introduction

The ESP8266 WiFi to UART module works with 3.3V, so to use it with Arduino UNO (working with 5V), it needs a simple adapter. First it needs a 3.3V power supply. It is recommended to use an external 3.3V voltage regulator, because the 3.3V pin from Arduino can not give too much current. Then the WiFi module also needs a level shifter on the RX pin, which can be made using two resistors. The TX pin from ESP8266 does not need a level shifter, because Arduino UNO "understands" 3.3V as HIGH level for digital input. A series resistor of 220 Ohm on the TX pin can be used for safety, for the case when the Arduino RX pin somehow gets to be an output.

Steps:

1.
Build the circuit according to the schematic.

2.
Connect to Arduino.

3.
Test.

4.
Use in your project and enjoy :)