ESP8266 WeMos D1 Mini

The ESP8266 WeMos D1 Mini has only one 3.3V output pin and also only one ground pin to power an external circuit. Today it is easy to create custom PCBs that are not expensive. If your project is ready for action you could put the WeMos D1 Mini on this custom PCB and more than one 3.3V pin and one ground for the PCB is not necessary. During the creation of the project, you can connect the 3.3V and ground pin with the rails of the breadboard to supply different electronic components.

The 5V pin has either the function as a power supply for the ESP8266 with voltages between 4V and 6 or can be used as 4.67V output when the ESP8266 WeMos D1 Mini is powered via USB. Therefore, you might also supply electronic components that need a supply voltage of 5V, because these components should also work with a supply voltage of 4.67V.

The ESP8266 WeMos D1 Mini has in total 9 digital input / output pins. All these 9 pins can create PWM signals and have a maximum output current of 12mA. You could also use the two UART pins that are not labeled as digital pins to get even 12 digital pins.

Unfortunately, the ESP8266 has only 1 analog input A0 that is connected internally with a 10-bit analog-to-digital converter (ADC) to convert the analog voltage into 1024 digital values between 0 and 1023.