Original Arduino Micro mit Atmega32u4

Der Arduino Micro ist ein Mikrocontroller-Board basierend auf dem Atmega32u4, welches in Zusammenarbeit mit Adafruit entwickelt wurde. Es verfügt über 20 digitale Ein-/Ausgangs-(I/O)-Pins (davon können 7 als PWM-Ausgänge und 12 analoge Eingänge verwendet werden), einen 16 MHz Quarz-Oszillator, einen Micro-USB-Anschluss, einen ICSP Header und einen Reset-Button.

Der Micro ist ähnlich zum Leonardo, welcher ebenfalls über den Atmega 32u4 verfügt. Durch die im Prozessor integrierte USB-Unterstützung wird kein separater IC mehr benötigt. Dies ermöglich es dem Micro, als Maus oder Tastatur zu agieren, zusätzlich Virtuellen COM-Port.

Das Board wird einfach mit einem Micro-USB-Kabel mit einem PC verbunden und schon kann es losgehen. Durch den 2.54mm-Formfaktor ist der Arduino Micro prädestiniert für Breadboards.

 
Technische Daten

Power

The Arduino 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 be 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 Arduino 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.
• ⏚ 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).

Communication

The Micro has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers. The ATmega32U4 provides UART TTL (5V) serial communication, which is available on digital pins 0 (RX) and 1 (TX). The 32U4 also allows for serial (CDC) communication over USB and appears as a virtual com port to software on the computer. The chip also acts as a full speed USB 2.0 device, using standard USB COM drivers. On Windows, a .inf file is required. The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the Arduino board. The RX and TX LEDs on the board will flash when data is being transmitted via the USB connection to the computer (but not for serial communication on pins 0 and 1).

A SoftwareSerial library allows for serial communication on any of the Micro's digital pins.

The ATmega32U4 also supports I2C (TWI) and SPI communication. The Arduino software includes a Wire library to simplify use of the I2C bus; see the documentation for details. For SPI communication, use the SPI library.

The Micro appears as a generic keyboard and mouse, and can be programmed to control these input devices using the Keyboard and Mouse classes.

Programming

The Micro can be programmed with the Arduino software (download). Select "Arduino Micro from the Tools > Board menu. For details, see the reference and tutorials.

The ATmega32U4 on the Arduino Micro comes pre-burned with a bootloader that allows you to upload new code to it without the use of an external hardware programmer. It communicates using the AVR109 protocol.

You can also bypass the bootloader and program the microcontroller through the ICSP (In-Circuit Serial Programming) header; see these instructions for details.

Automatic (Software) Reset and Bootloader Initiation

Rather than requiring a physical press of the reset button before an upload, the Micro is designed in a way that allows it to be reset by software running on a connected computer. The reset is triggered when the Micro's virtual (CDC) serial / COM port is opened at 1200 baud and then closed. When this happens, the processor will reset, breaking the USB connection to the computer (meaning that the virtual serial / COM port will disappear). After the processor resets, the bootloader starts, remaining active for about 8 seconds. The bootloader can also be initiated by pressing the reset button on the Micro. Note that when the board first powers up, it will jump straight to the user sketch, if present, rather than initiating the bootloader.

Because of the way the Micro handles reset it's best to let the Arduino software try to initiate the reset before uploading, especially if you are in the habit of pressing the reset button before uploading on other boards. If the software can't reset the board you can always start the bootloader by pressing the reset button on the board.

USB Overcurrent Protection

The Micro has a resettable polyfuse that protects your computer's USB ports from shorts and overcurrent. Although most computers provide their own internal protection, the fuse provides an extra layer of protection. If more than 500 mA is applied to the USB port, the fuse will automatically break the connection until the short or overload is removed.

Physical Characteristics

The maximum length and width of the Micro PCB are 4.8cm and 1.77cm respectively, with the USB connector extending beyond the former dimension. The layout allows for easy placement on a solderless breadboard..

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