The ESP-01S module features an onboard Blue LED that is intricately connected to GPIO2. In the module's schematics, you'll observe that the VCC (Postive) is first channeled through a 1K resistor, and then it is linked to the anode (positive terminal) of this onboard Blue LED. Meanwhile, the cathode (negative terminal) of the LED is connected to the ESP-01S GPIO2.

This configuration contrasts with the onboard LED of the Arduino UNO R3. In the ESP-01S, the behavior is reversed. Specifically, when GPIO2 is set to a logic LOW state, it closes the circuit, causing the LED to illuminate. Conversely, when GPIO2 is set to a logic HIGH state, it opens the circuit, resulting in the LED being turned off. This inverted operation is a notable distinction to keep in mind when working with the ESP-01S module.

Wire connections are not required for this project. You may refer to the ESP-01 schematics section below.