This page explains how to build an adapter for the ESP-01 WiFi module to connect its UART to Arduino Serial.
- 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
- soldering iron + solder
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.
Build the circuit according to the schematic.
Connect to Arduino.
Use in your project and enjoy :)