Arduino Compatible Pro Micro

The Micro is a microcontroller board based on the ATmega32U4. It has 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, a micro USB connection, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a micro USB cable to get started. It has a form factor that enables it to be easily placed on a breadboard.

The Micro board is similar to the Arduino Leonardo in that the ATmega32U4 has built-in USB communication, eliminating the need for a secondary processor. This allows the Micro to appear to a connected computer as a mouse and keyboard, in addition to a virtual (CDC) serial / COM port.

Specifications:

• Microcontroller : ATmega32U4
• Operating Voltage : 5V
• Input Voltage (recommended) : 7-9V
• Input Voltage (limit) : 6-9V
• Digital I/O Pins : 20
• PWM Channels : 7
• Analog Input Channels : 12
• DC Current per I/O Pin : 20 mA
• DC Current for 3.3V Pin : 50 mA
• Flash Memory : 32 KB (ATmega32U4) of which 4 KB used by bootloader
• SRAM : 2.5 KB (ATmega32U4)
• EEPROM : 1 KB (ATmega32U4)
• Clock Speed : 16MHz
• LED_BUILTIN : 13
• Dimensions (L X W) : 48 mm x 18mm
• Weight : 18g

Power

The Micro can be powered via the micro USB connection or with an external power supply. The power source is selected automatically. External (non-USB) power can come either from a DC power supply or battery. Leads from a battery or DC power supply can be connected to the Gnd and Vin pins. The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may become unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.

The power pins are as follows:

• VI – The input voltage to the MICRO board when it’s using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin.
• 5V – The regulated power supply used to power the microcontroller and other components on the board. This can come either from VIN via an on-board regulator, or be supplied by USB or another regulated 5V supply.
• 3V –  A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 mA.
• GND – Ground pins.

Memory

The ATmega32U4 has 32 KB (with 4 KB used for the bootloader). It also has 2.5 KB of SRAM and 1 KB of EEPROM (which can be read and written with the EEPROM library).