The ESP-01 WiFi Module Shield provides a convenient connection between an Arduino and an ESP-01 module.
The shield provides a 3.3V power supply for the module, and logic level converters so it can operate with either 3.3V or 5V Arduino boards.
1. Mount the shield on your Arduino.
2. Mount your ESP-01 module on the shield using the header provided. The module must be oriented to align with the marking on the shield.
3. Configure the serial jumpers near the top right of the shield to suit the pins your Arduino will use for communication with the ESP-01 module. The module ships with jumpers in a default position as shown above to connect the module's TX line to Arduino pin D2, and the module's RX line to Arduino pin D3. This means your Arduino will need to transmit on D3 (to the module's RX line) and receive on D2 from the module's TX line.
4. Configure the reset jumper to connect module reset to Arduino reset. With the jumper in place (labelled "RST-LNK" on the PCB) the module's reset line is connected to the Arduino reset line, so when you press the Arduino RESET button your module will also be reset. This is a good way to ensure the module always starts in a known state when your Arduino resets. However, if you wish to isolate your module from Arduino reset you can remove the RST-LNK jumper. The jumper is fitted by default.
The software required to use your ESP-01 depends on the firmware it has installed. The most common firmware shipped on the modules provides a WiFi bridge that can be controlled via "AT" serial commands from your Arduino. You can, therefore, use your Arduino as a "serial reflector" to pass commands and responses between your computer and the module, allowing you to type commands in the Arduino IDE serial console and see how the module replies.