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<\/p>\nThe Uno R3 without Cable is a micro-controller board base on the ATmega328 . It has 14 digital input\/output pins (of which 6 can be used as PWM outputs); 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button.<\/p>\n
It contains everything need to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.<\/p>\n
\u201cUno\u201d means one in Italian and is the name to mark the upcoming release of Arduino 1.0. The Uno and version 1.0 will be the reference versions of Arduino, moving forward. The Uno is the latest in a series of USB Arduino boards and the reference model for the Arduino platform; for a comparison with previous versions, see the\u00a0index of Arduino boards.<\/p>\n
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The Uno R3 can be powered via the USB connection or with an external power supply. The power source is selected automatically.<\/p>\n
External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board\u2019s power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector.<\/p>\n
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.<\/p>\n
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The\u00a0ATmega328<\/span>\u00a0has 32 KB (with 0.5 KB used for the bootloader). It also has 2 KB of SRAM and 1 KB of EEPROM<\/p>\n Each of the 14 digital pins on the Uno can be used as an input or output, using\u00a0pinMode(),\u00a0digitalWrite(), and\u00a0digitalRead()\u00a0functions. They operate at 5 volts. Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor (disconnected by default) of 20-50 kOhms. In addition, some pins have specialized functions:<\/p>\n <\/p>\n The Uno R3 has 6 analog inputs, labeled A0 through A5, each of which provides 10 bits of resolution (i.e. 1024 different values). By default, they measure from ground to 5 volts, though is it possible to change the upper end of their range using the AREF pin and the\u00a0analogReference() function. Additionally, some pins have specialized functionality:<\/p>\n There are a couple of other pins on the board:<\/p>\n See also the\u00a0mapping between Arduino pins and ATmega328 ports. The mapping for the Atmega8, 168, and 328 is identical.<\/p>\n The Uno R3 has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers. The\u00a0ATmega328<\/span>\u00a0provides UART TTL (5V) serial communication, which is available on digital pins 0 (RX) and 1 (TX). An\u00a0ATmega16U2<\/span>\u00a0on the board channels this serial communication over USB and appears as a virtual com port to software on the computer. The \u201916U2 firmware uses the standard USB COM drivers, and no external driver is needed. However,\u00a0on 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\u00a0LEDs<\/span>\u00a0on the board will flash when data is being transmitted via the USB-to-serial chip and USB connection to the computer (but not for serial communication on pins 0 and 1).<\/p>\n A\u00a0SoftwareSerial library\u00a0allows for serial communication on any of the Uno\u2019s digital pins.<\/p>\n The\u00a0ATmega328<\/span>\u00a0also supports\u00a0I2C<\/span>\u00a0(TWI) and SPI communication. The Uno R3 software includes a Wire library to simplify use of the\u00a0I2C<\/span>\u00a0bus; see the\u00a0documentation\u00a0for details. For SPI communication, use the\u00a0SPI library.<\/p>\n The Uno R3 can be a program with the Arduino software . Select \u201cArduino Uno from the Tools > Board menu (according to the microcontroller on your board). For details, see the\u00a0reference\u00a0and\u00a0tutorials.<\/p>\n The\u00a0ATmega328<\/span>\u00a0on the Uno R3 comes pre-burn with a\u00a0bootloader\u00a0that allows you to upload new code to it without the use of an external hardware programmer. It communicates using the original\u00a0STK500<\/span>\u00a0protocol (reference,\u00a0C header files).<\/p>\n You can also bypass the bootloader and program the microcontroller through the ICSP (In-Circuit Serial Programming) header; see\u00a0these instructions<\/a>\u00a0for details.<\/p>\n The\u00a0ATmega16U2<\/span>\u00a0(or 8U2 in the rev1 and rev2 boards) firmware source code is available. The\u00a0ATmega16U2<\/span>\/8U2 is load with a DFU bootloader, which can be activated by:<\/p>\n You can then use\u00a0Atmel\u2019s FLIP software\u00a0(Windows) or the\u00a0DFU programmer\u00a0(Mac OS X and Linux) to load a new firmware. Or you can use the ISP header with an external programmer (overwriting the DFU bootloader). See\u00a0this user-contributed tutorial<\/a>\u00a0for more information.<\/p>\n Rather than requiring a physical press of the reset button before an upload, the Arduino Uno is designed in a way that allows it to be reset by software running on a connected computer. One of the hardware flow control lines (DTR) of theATmega8U2<\/span>\/16U2 is connected to the reset line of the\u00a0ATmega328<\/span>\u00a0via a 100 nano-farad capacitor. When this line is asserted (taken low), the reset line drops long enough to reset the chip. The Arduino software uses this capability to allow you to upload code by simply pressing the upload button in the Arduino environment. This means that the boot-loader can have a shorter timeout, as the lowering of DTR can be well-coordinated with the start of the upload.<\/p>\n This setup has other implications. When the Uno is connected to either a computer running Mac OS X or Linux, it resets each time a connection is made to it from software (via USB). For the following half-second or so, the boot-loader is running on the Uno. While it is a program to ignore malformed data (i.e. anything besides an upload of new code), it will intercept the first few bytes of data sent to the board after a connection is open. If a sketch running on the board receives one-time configuration or other data when it first starts, makes sure that the software with which it communicates waits for a second after opening the connection and before sending this data.<\/p>\nInput and Output<\/strong><\/h5>\n
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Communication<\/strong><\/h5>\n
Programming<\/strong><\/h5>\n
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Automatic (Software) Reset<\/strong><\/h5>\n