A 26.000MHz crystal is used in the ESP-01/ESP-01S module. In order to use the ESP-01 Wi-Fi relay module, a programmer/programming adapter is required to program the ESP-01 module (see below). Also it ...

It comes with a pre-installed AT firmware, hence we can program it using Arduino IDE. You can learn more about the ESP-01 Wi-Fi transceiver and its programming using Arduino IDE by following the link.

Hardware_serial_test is for tesing whether your esp01 wifi module is working or not this can be used for any Arduino board having only one serial communication channel. 2.Software_serial_test is for ...

C4 and C5 are used as decoupling capacitors. The “Serial” is a 3-Pin 2.5mm XH connector to connect a TTL USB-to-Serial converter to the board. It is used the program the module and read the serial ...