The module is based on Atmel's mega34u4 chip, and the supply voltage is a very cool small development board with usb 5V. 

It is an Arduino-compatible microcontroller with a miniature size, and only one chip can complete the functions that the old Arduino Unos, Duemilanoves and Diecimeillas never dreamed of:

real USB function.

Dig deeper into what pins can do ...

The power pin has a variety of power supplies and the network related to the power supply is broken:

RAW is Pro Micro's unregulated voltage input. If the board is powered by USB,

the voltage on this pin is about 4.8V (USB 5V minus Schottky diode voltage drop). 

On the other hand, if the board is externally powered through this pin, the applied voltage can be up to 12V. 

VCC is the voltage supplied to the onboard ATmega32U4. 

This voltage depends on whether you are using the 3.3V / 8MHz Pro Micro or 5V / 16MHz version, which is 3.3V or 5V, respectively. 

This voltage is adjusted by the voltage applied to the RAW pin. 

If the development board is powered via the "RAW" pin (or USB),

this pin can be used as an output to power other devices. 

RST can be used to restart Pro Micro. 

This pin is pulled up by 10kΩ. 

The resistance on the board is active low,

so it must be grounded to initiate a reset. 

Pro Micro will remain "off" until the reset line is pulled back to a high level. 

GND is of course the common ground voltage of the system (0V reference). 

I / O Pins Pro Micro's I / O pins (18 total) are versatile. 

Each pin can be used as a digital input or output to flash the LED or press a button. 

These pins are referenced in the Arduino IDE by integer values ??between 0 and 21. 

(A0-A3 pins can be digitally referenced using their analog or digital pin numbers).

Nine pins have an analog-to-digital converter (ADC), which can be used as an analog input. 

These are useful for reading potentiometers or other analog devices using the analogRead ([pin]) function.

There are five pins with a pulse width modulation (PWM) function that allow this function to be used to perform some form of analog output analogWrite ([pin], [value]). 

These pins appear as light white circles on the board.

Hardware UART (serial), I 2 C and SPI pins are also provided. 

These can be used to interface with serial LCD, XBees, IMU and other serial sensors and other digital devices.

Pro Micro has five external interrupts.

When the pin goes high or low (or goes high or low at the same time),

they allow you to trigger the function immediately. 

If you attach an interrupt to a pin with interrupt enabled,

you need to know the specific interrupt triggered by that pin: pin 3 is mapped to interrupt 0 (INT0), pin 2 is interrupt 1 (INT1), pin 0 is interrupt 2 (INT2), pin 1 is interrupt 3 (INT3), pin 7 is interrupt 4 (INT6).

There are three LEDs on the onboard LED Pro Micro. A red LED indicator indicates whether there is electricity.

The other two LEDs help indicate when to transfer data via USB. 

The yellow LED indicator indicates that the USB data is entering Pro Micro (RX),

and the green LED indicator indicates that the USB data is coming out (TX).

How to Power Pro Micro Because Pro Micro's main function is its inherent USB function, the most commonly used power supply method is via USB. 

In this setting, 5V Pro Micro will be powered directly via the USB bus,

while 3.3V Pro Micro will regulate the 5V power supply that is

disconnected from the USB. 

The other end of the USB cable can be connected to a computer,

USB hub or USB wall adapter, and they can (in most cases) provide more power.

In addition, if Pro Micro survives in the wild where the USB cable cannot reach,

it can be powered through the "RAW" or "VCC" pin. 

Once the supply enters the "RAW" pin it will be adjusted to the appropriate operating voltage (5V or 3.3V). 

For safety reasons, this voltage should not be higher than 12V,

and should be at least 1V higher than the operating voltage of Pro Micro (for example, for 5V Pro Micro, it should be greater than 6V).

If you supply power to Pro Micro via the "VCC" pin, remember that the signal is unstable. Only use it if you have a clean, stable 3.3V or 5V power connection.