The Arduino Due is designed to be compatible with most shields designed for the Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and GND pins), analog inputs 0 to 5, the power header, and "ICSP" (SPI) header are all in equivalent locations. Further the main UART (serial port) is located on the same pins (0 and 1). Please note that I²C is not located on the same pins on the Due (20 and 21) as the Duemilanove / Diecimila (analog inputs 4 and 5).

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The board contains everything needed to support the microcontroller; simply connect it to a computer with a micro-USB cable or power it with a AC-to-DC adapter or battery to get started. The Due is compatible with all Arduino shields that work at 3.3V and are compliant with the 1.0 Arduino pinout.

• Programming port: To use this port, select "Arduino Due (Programming Port)" as your board in the Arduino IDE. Connect the Due's programming port (the one closest to the DC power jack) to your computer. The programming port uses the 16U2 as a USB-to-serial chip connected to the first UART of the SAM3X (RX0 and TX0). The 16U2 has two pins connected to the Reset and Erase pins of the SAM3X. Opening and closing the Programming port connected at 1200bps triggers a “hard erase” procedure of the SAM3X chip, activating the Erase and Reset pins on the SAM3X before communicating with the UART. This is the recommended port for programming the Due. It is more reliable than the "soft erase" that occurs on the Native port, and it should work even if the main MCU has crashed.

• Programming port: To use this port, select "Arduino Due (Programming Port)" as your board in the Arduino IDE. Connect the Due's programming port (the one closest to the DC power jack) to your computer. The programming port uses the 16U2 as a USB-to-serial chip connected to the first UART of the SAM3X (RX0 and TX0). The 16U2 has two pins connected to the Reset and Erase pins of the SAM3X. Opening the Programming port triggers a “hard erase” procedure of the SAM3X chip, activating the Erase and Reset pins on the SAM3X before communicating with the UART. This is the recommended port for programming the Due. It is more reliable than the "soft erase" that occurs on the Native port, and it should work even if the main MCU has crashed.

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The Arduino Due is designed to be compatible with most shields designed for the Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and GND pins), analog inputs 0 to 5, the power header, and "ICSP" (SPI) header are all in equivalent locations. Further the main UART (serial port) is located on the same pins (0 and 1). Please note that I²C is not located on the same pins on the Due (20 and 21) as the Duemilanove / Diecimila (analog inputs 4 and 5).

The Native USB port is connected to the SAM3X. It allows for serial (CDC) communication over USB. This provides a serial connection to the Serial Monitor or other applications on your computer. It also enables the Due to emulate a USB mouse or keyboard to an attached computer. To use these features, see the Mouse and Keyboard library reference pages.

• Native port: To use this port, select "Arduino Due (Native USB Port)" as your board in the Arduino IDE. The Native USB port is connected directly to the SAM3X. Connect the Due's Native USB port (the one closest to the reset button) to your computer. Opening and closing the Native port at 1200bps triggers a 'soft erase' procedure: the flash memory is erased and the board is restarted with the bootloader. If the MCU crashed for some reason it is likely that the soft erase procedure won't work as this procedure happens entirely in software on the SAM3X. Opening and closing the native port at a different baudrate will not reset the SAM3X.

The Due has a dedicated forum for discussing the board.

The Arduino Due can be programmed with the Arduino software (download). For details, see the reference and tutorials.

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The Native USB port allows for serial (CDC) communication over USB. This provides a serial connection to the Serial Monitor or other applications on your computer. It also enables the Due to emulate a USB mouse or keyboard to an attached computer. To use these features, see the Mouse and Keyboard library reference pages.

• Programming port: To use this port, select "Arduino Due (Programming Port)" as your board in the Arduino IDE. Connect the Due's programming port (the one closest to the DC power jack) to your computer. The programming port uses the 16U2 as a USB-to-serial chip connected to the first UART of the SAM3X (RX0 and TX0). The 16U2 has two pins connected to the Reset and Erase pins of the SAM3X. Opening and closing the Programming port connected at 1200bps triggers a “hard erase” procedure of the SAM3X chip, activating the Erase and Reset pins on the SAM3X before communicating with the UART. This is the recommended port for programming the Due. It is more reliable than the "soft erase" that occurs on the Native port, and it should work even if the main MCU has crashed.

• Native port: To use this port, select "Arduino Due (Native USB Port)" as your board in the Arduino IDE. Connect the Due's native USB port (the one closest to the reset button) to your computer. Opening and closing the Native port at 1200bps triggers a 'soft erase' procedure: the flash memory is erased and the board is restarted with the bootloader. If the MCU crashed for some reason it is likely that the soft erase procedure won't work as this procedure happens entirely in software on the SAM3X. Opening and closing the native port at a different baudrate will not reset the SAM3X.

Unlike other Arduino boards which use avrdude for uploading, the Due relies on bossac.

The ATmega16U2 firmware source code is available in the Arduino repository. You can use the ISP header with an external programmer (overwriting the DFU bootloader). See this user-contributed tutorial for more information.

The Native USB port allows for serial (CDC) communication over USB. This enables the Due to emulate a USB mouse or keyboard to an attached computer. To use these features, see the Mouse and Keyboard library reference pages.

The Native USB port has the ability to operate as a USB-CDC connection. That is, the Due can emulate a USB mouse or keyboard to an attached computer. To use these features, see the Mouse and Keyboard library reference pages.

The Arduino Due is designed to be compatible with most shields designed for the Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and GND pins), analog inputs 0 to 5, the power header, and "ICSP" (SPI) header are all in equivalent locations. Further the main UART (serial port) is located on the same pins (0 and 1), as are external interrupts 0 and 1 (pins 2 and 3 respectively). Please note that I²C is not located on the same pins on the Due (20 and 21) as the Duemilanove / Diecimila (analog inputs 4 and 5).

• Programming port: The programming port uses the 16U2 as a USB-to-serial chip connected to the first UART of the SAM3X (RX0 and TX0). The 16U2 has two pins connected to the Reset and Erase pins of the SAM3X. Opening and closing the Programming port connected at 1200bps triggers a “hard erase” procedure of the SAM3X chip, activating the Erase and Reset pins on the SAM3X before communicating with the UART. This is the recommended port for programming the Due. It is more reliable than the "soft erase" that occurs on the Native port, and it should work even if the main MCU has crashed.

The Arduino Due has a number of facilities for communicating with a computer, another Arduino or other microcontrollers, and different devices like phones, tablets, cameras and so on. The SAM3X provides one hardware UART and three hardware USARTs for TTL (3.3V) serial communication.

The Programming port is connected to an ATmega16U2, which provides a virtual COM port to software on a connected computer (To recognize the device, Windows machines will need a .inf file, but OSX and Linux machines will recognize the board as a COM port automatically.). The 16U2 is also connected to the SAM3X hardware UART. Serial on pins RX0 and TX0 provides Serial-to-USB communication for programming the board through the ATmega16U2 microcontroller. The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the ATmega16U2 chip and USB connection to the computer (but not for serial communication on pins 0 and 1).

The Native USB port has the ability to operate as a USB-CDC connection. That is, the Due can emulate a USB mouse or keyboard to an attached computer.

The Native USB port can also act as a USB host for connected peripherals such as mice, keyboards, and smartphones. To use these features, see the USBHost reference pages.

Uploading sketches to the SAM3X is different than the AVR microcontrollers found in other Arduino boards because the flash memory needs to be erased before being re-programmed. Upload to the chip is managed by ROM on the SAM3X, which is run only when the chip's flash memory is empty.

Either of the USB ports can be used for programming the board, though it is recommended to use the Programming port due to the way the erasing of the chip is handled :

• Programming port: The programming port uses the 16U2 as a USB-to-serial chip connected to the first UART of the SAM3X (RX0 and TX0). The 16U2 has two pins connected to the Reset and Erase pins of the SAM3X. Opening and closing the Programming port connected at 1200bps triggers a “hard erase” procedure of the SAM3X chip, activating the Erase and Reset pins on the SAM3X before communicating with the UART.

This is the recommended port for programming the Due. It is more reliable than the "soft erase" that occurs on the Native port, and it should work even if the main MCU has crashed.

• Native port: Opening and closing the Native port at 1200bps triggers a 'soft erase' procedure: the flash memory is erased and the board is restarted with the bootloader. If the MCU crashed for some reason it is likely that the soft erase procedure won't work as this procedure happens entirely in software on the SAM3X. Opening and closing the native port at a different baudrate will not reset the SAM3X.

The Arduino Due is designed to be compatible with most shields designed for the Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and GND pins), analog inputs 0 to 5, the power header, and "ICSP" (SPI) header are all in equivalent locations. Further the main UART (serial port) is located on the same pins (0 and 1), as are external interrupts 0 and 1 (pins 2 and 3 respectively). Please note that I²C is not located on the same pins on the Due (20 and 21) as the Duemilanove / Diecimila (analog inputs 4 and 5).

It is possible to erase the Flash memory of the SAM3X with the onboard erase button. This will remove the currently loaded sketch from the MCU. To erase, press and hold the Erase button for a few seconds while the board is powered.

• Native port: opening and closing the native port at the magic baud rate of 1200bps trigger the "soft erase" procedure: the flash memory is erased and the board is restarted with the bootloader, but if the MCU crashed for some reason it is likely that the soft erase procedure didn’t work since its done entirely in software by the MCU itself. Opening and closing the native port at a different baudrate will not reset the SAM3X.

• Programming port: The programming port uses a USB-to-serial chip connected to the first UART of the MCU (RX0 and TX0). The USB-to-serial chip has two pins connected to the Reset and Erase pins of the SAM3X and when you open this serial port the USB-to-Serial ectivate the Erase and Reset sequence before start to talk with the UART of the SAM3X.

Warning: Unlike other Arduino boards, the Arduino Due board runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Providing higher voltages, like 5V to an I/O pin could damage the board.

The SAM3X microcontroller is different from AVR microcontroller because the flash memory need to be erased before being re-programmed. So this means that if you should do this procedure manually, before pressing the upload button on the IDE you should hold the erase button on the board for a second and then the reset, after that uploading a sketch will be done succesfully.

Because this procedure is repetitive, this task is managed automatically from both the USB ports, in two different ways:

• Native port: opening and closing the native port at the magic baud rate of 1200bps trigger the "soft erase" procedure: the flash memory is erased and the board is restarted with

the bootloader, but if the MCU crashed for some reason it is likely that the soft erase procedure didn’t work since its done entirely in software by the MCU itself.

• Programming port: The programming port uses a USB-to-serial chip connected to the first UART of the MCU (RX0 and TX0). The USB-to-serial chip has two pins connected to

the Reset and Erase pins of the SAM3X and when you open this serial port the USB-to-Serial ectivate the Erase and Reset sequence before start to talk with the UART of the SAM3X. This procedure is much more reliable and it should work even if the main MCU has crashed.

The Due has 12 analog inputs, each of which can provide 12 bits of resolution (i.e. 4096 different values). By default, the resolution of the readings is set at 10 bits, for compatibility with other Arduino boards. It is possible to change the resolution of the ADC with analogReadResolution(). The Due's analog inputs pins measure from ground to a maximum value of 3.3V. The analogReference() function is ignored on the Due.

Firmware upload

Opening and closing the USBSerial at 1200bps triggers a 'soft erase' procedure: the flash memory is erased and the board is restarted with the bootloader. If the MCU crashed for some reason it is likely that the soft erase procedure won't work as this procedure happens entirely in software on the SAM3X.

Opening and closing the Serial port connected to the 16u2 at 1200bps triggers a “hard erase” procedure of the SAM3x chip, activating the Erase and Reset pins on the SAM3X. This procedure is more reliable than the "soft erase" mentioned above, and should work even if the main MCU has crashed.

The Due has 12 analog inputs, each of which can provide 12 bits of resolution (i.e. 4096 different values). By default, the resolution of the readings is set at 10 bits, for compatibility with other Arduino boards. It is possible to change the resolution of the ADC with analogReadResolution(). The Due's analog inputs pins measure from ground to a maximum value of 3.3V, though it is possible to set a lower analog reference value through the AREF pin and the analogReference() function.

The USBSerial port connected to the SAM3X can operate as a USB-CDC connection. That is, the Due can act as a USB host for connected peripherals such as mice, keyboards, and smartphones. To use these features, see the USBHost reference pages.

When programming the Due with the default port through the USB-Serial connection (adjacent to the power jack), the 16u2 acts as an intermediary, doing a hardware erase and reset of the SAM3X chip. If using the USBSerial connection for

Warning: Unlike other Arduino boards, the Arduino Due board runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Providing higher voltages, like 5V to an I/O pin could damage the board.

• The IOREF pin which allows an attached shield with the proper configuration to adapt to the voltage provided by the board. This enables shield compatibility with a 3.3V board like the Due and AVR-based boards which operate at 5V.

Pin Mapping: SAM3X Pin Mapping page

• IOREF. This pin on the Arduino board provides the voltage reference with which the microcontroller operates. A properly configured shield can read the IOREF pin voltage and select the appropriate power source or enable voltage translators on the outputs for working with the 5V or 3.3V.

It is possible to erase the Flash memory with the onboard erase button. This will remove the currently loaded sketch from the SAM3X.

Used to receive (RX) and transmit (TX) TTL serial data (with 3.3 V level). Pins 0 and 1 are connected to the corresponding pins of the ATmega16U2 USB-to-TTL Serial chip.

• Analog Inputs: pins from A0 to A11
  The Due has 12 analog inputs, each of which can provide 12 bits of resolution (i.e. 4096 different values). By default, the resolution of the readings is set at 10 bits, for compatibility with other Arduino boards. It is possible to change the resolution of the ADC with analogReadResolution(). The Due's analog inputs pins measure from ground to 3.3 volts, though is it possible to change the upper end of their range using the AREF pin and analogReference() function.

• DAC1 and DAC2
  These pins provides true analog outputs with 12-bits resolution (4096 levels) with the analogWrite() function. These pins can be used to create an audio output using the Audio library.

The Arduino Due has a number of facilities for communicating with a computer, another Arduino or other microcontrollers and different devices like phones, tablets, cameras and so on. The SAM3X provides one hardware UART, connected to one of the onboard USB connectors (USBSerial), and three hardware USARTs for TTL (3.3V) serial communication. Serial on pins RX0 and TX0 provides Serial-to-USB communication used for programming the board through the ATmega16U2 microcontroller. The 16U2 provides a virtual COM port to software on the computer (Windows machines will need a .inf file, but OSX and Linux machines will recognize the board as a COM port automatically). The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the ATmega16U2 chip and USB connection to the computer (but not for serial communication on pins 0 and 1).

The USBSerial port connected to the SAM3X can operate as a USB-CDC connection. That is, the Due can act as a USB host for connected peripherals such as mice, keyboards, and smartphones. To access these features, use the USBHost reference pages.

The SAM3X also supports TWI and SPI communication. The Arduino software includes a Wire library to simplify use of the TWI bus; see the documentation for details. For SPI communication, use the SPI library.

The Arduino Due is designed to be compatible with most shields designed for the Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and GND pins), analog inputs 0 to 5, the power header, and "ICSP" (SPI) header are all in equivalent locations. Further the main UART (serial port) is located on the same pins (0 and 1), as are external interrupts 0 and 1 (pins 2 and 3 respectively). Please note that I²C is not located on the same pins on the Due (20 and 21) as the Duemilanove / Diecimila (analog inputs 4 and 5).

[MISSING: erase button that erase the flash memory]

The Arduino Due has a number of facilities for communicating with a computer, another Arduino or other microcontrollers and different devices like phones, tablets, cameras and so on. The SAM3X provides one hardware UART, connected to RX0 and TX0, and three hardware USARTs for TTL (3.3V) serial communication. Serial on pins RX0 and TX0 also provides the Serial-to-USB communication used for programming the board through the ATmega16U2 microcontroller that provides a virtual COM port to software on the computer (Windows machines will need a .inf file, but OSX and Linux machines will recognize the board as a COM port automatically). The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the ATmega16U2 chip and USB connection to the computer (but not for serial communication on pins 0 and 1).

[MISSING: USB-CDC with SerialUSB]

The ATmega16U2 firmware source code is available in the Arduino repository. You can use the ISP header with an external programmer (overwriting the DFU bootloader). See this user-contributed tutorial for more information.

[MISSING: describe here the automatic 'erase' procedure]

[MISSING: describe here that the board doesn't automatically restart the sketch if you open the serial monitor like on the Uno]

Rather then requiring a physical press of the reset button before an upload, the Arduino Due is designed in a way that allows it to be reset by software running on a connected computer.

The Arduino Due is designed to be compatible with most shields designed for the Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and GND pins), analog inputs 0 to 5, the power header, and "ICSP" (SPI) header are all in equivalent locations. Further the main UART (serial port) is located on the same pins (0 and 1), as are external interrupts 0 and 1 (pins 2 and 3 respectively). Please note that I²C is not located on the same pins on the Due (20 and 21) as the Duemilanove / Diecimila (analog inputs 4 and 5).

The Arduino Due is a microcontroller board based on the Atmel SAM3X8E ARM Cortex-M3 CPU (datasheet). It is the first Arduino board based on a 32-bit ARM core microcontroller. It has 54 digital input/output pins (of which 12 can be used as PWM outputs), 12 analog inputs, 4 UARTs (hardware serial ports), a 84 MHz clock, an USB OTG capable connection, 2 DAC (digital to analog), 2 TWI, a power jack, an SPI header, a JTAG header, a reset button and an erase button.

Warning: differently from other Arduino boards, the Arduino Due board runs at 3.3V, therefore the maximum voltage that the I/O pins can tolerate is 3.3V. Providing higher voltages, like 5V to an I/O pin could damage the board.

The board contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Due is compatible with all Arduino shields that work at 3.3V and are compliant with the 1.0 Arduino pinout.

The Due follows the 1.0 pinout:

• TWI: SDA and SCL pins that are near to the AREF pin.

The Due has a 32-bit ARM core that can outperform typical 8-bit microcontroller boards. The most significant differences are:

• A 32-bit core, that allows operations on 4 bytes wide data within a single CPU clock. (for more information look int type page).
• CPU Clock at 84Mhz.
• 96 KBytes of SRAM.
• 512 KBytes of Flash memory for code.
• a DMA controller, that can relieve the CPU from doing memory intensive tasks.

The Arduino Due can be powered via the USB connector or with an external power supply. The power source is selected automatically.

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's power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector.

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 SAM3X has 512 KB (2 blocks of 256 KB) of flash memory for storing code. The bootloader is preburned in factory from Atmel and is stored in a dedicated ROM memory. The available SRAM is 96 KB in two contiguous bank of 64 KB and 32 KB. All the available memory (Flash, RAM and ROM) can be accessed directly as a flat addressing space.

• Digital I/O: pins from 0 to 53
  Each of the 54 digital pins on the Due can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 3.3 volts. Each pin can provide (source) a current of 3 mA or 15 mA, depending on the pin, or receive (sink) a current of 6 mA or 9 mA, depending on the pin. They also have an internal pull-up resistor (disconnected by default) of 100 KOhm. In addition, some pins have specialized functions:

• Analog Inputs: pins from A0 to A11
  The Due has 12 analog inputs, each of which provide 12 bits of resolution (i.e. 4096 different values). By default the resolution of the readings is set at 10 bits, for compatibility with other Arduino boards. It is possible to change the resolution of the ADC with analogReadResolution(). The Due's analog inputs pins measure from ground to 3.3 volts, though is it possible to change the upper end of their range using the AREF pin and analogReference() function.

• Serial: 0 (RX) and 1 (TX)
• Serial 1: 19 (RX) and 18 (TX)
• Serial 2: 17 (RX) and 16 (TX)
• Serial 3: 15 (RX) and 14 (TX)
  Used to receive (RX) and transmit (TX) TTL serial data (with 3.3 V level). Pins 0 and 1 are also connected to the corresponding pins of the ATmega16U2 USB-to-TTL Serial chip.

• PWM: Pins 2 to 13
  Provide 8-bit PWM output with the analogWrite() function. the resolution of the PWM can be changed with the analogWriteResolution() function.

• SPI: SPI header (ICSP header on other Arduino boards)
  These pins support SPI communication using the SPI library. The SPI pins are broken out on the central 6-pin header, which is physically compatible with the Uno, Leonardo and Mega2560. The SPI header can be used only to communicate with other SPI devices, not for programming the SAM3X with the In-Circuit-Serial-Programming technique. The SPI of the Due has also advanced features that can be used with the Extended SPI methods for Due.

• DAC1 and DAC2
  These pins provides two real analog outputs with 12-bits resolution (4096 levels) with the analogWrite() function. These pins can be used to create an audio output using the Audio library.

• CAN: CANRX and CANTX
  These pins support the CAN communication protocol but are not not yet supported by Arduino APIs.

• "L" LED: 13
  There is a built-in LED connected to digital pin 13. When the pin is HIGH, the LED is on, when the pin is LOW, it's off. It is also possible to dim the LED because the digital pin 13 is also a PWM outuput.

• TWI 1: 20 (SDA) and 21 (SCL)
• TWI 2: SDA1 and SCL1.
  Support TWI communication using the Wire library.

• AREF
  Reference voltage for the analog inputs. Used with analogReference().

• Reset
  Bring this line LOW to reset the microcontroller. Typically used to add a reset button to shields which block the one on the board.

The Due contains a trace that can be cut to disable the auto-reset. The pads on either side of the trace can be soldered together to re-enable it. It's labeled "RESET-EN". You may also be able to disable the auto-reset by connecting a 110 ohm resistor from 5V to the reset line; see this forum thread for details.

ARM Core benefits

The Due has a 32-bit ARM core and so "int" is 32-bits. On the AVRs on other Arduino boards, an int is 16 bits. For further information see the int type page.

The Arduino Due is a microcontroller board based on the Atmel SAM3X8E ARM Cortex-M3 CPU (datasheet). It has 54 digital input/output pins (of which 16 can be used as PWM outputs), 12 analog inputs, 4 UARTs (hardware serial ports), a 84 MHz crystal oscillator, two USB connections, a power jack, an ICSP header, a JTAG header, and a reset button. The maximum voltage that the I/O pins can provide or tolerate is 3.3V. Providing higher voltages, like 5V to an input pin could damage the board.

It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Due is compatible with all Arduino shields that work at 3.3V and are compliant with the 1.0 Arduino pinout.

The Due has the 1.0 pinout :

• TWI SDA and SCL pins that are near to the AREF pin.
• The IOREF pin which allows an attached shield with the proper configuration to adapt to the voltage provided by the board. This enabled compatibility with a 3.3V board like the Due as well as with AVR based boards which operate at 5V.
• An unconnected pin, reserved for future use.
• Atmega 16U2 for USB-to-Serial conversion and for managing the reset and erase procedure.

• VIN. 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, or if supplying voltage via the power jack, access it through this pin.

• 3.3V. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 800 mA. This regulator also provides the power supply to the SAM3X microcontroller.

• IOREF. This pin on the Arduino board provides the voltage reference with which the microcontroller operates. A shield can read the IOREF pin voltage can select the power source or enable voltage translators on the outputs for working with the 5V or 3.3V.

Each of the 54 digital pins on the Due can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 3.3 volts. Each pin can provide (source) a current between 3 and 15 mA or receive (sink) a current between 6 and 9 mA. They also have an internal pull-up resistor (disconnected by default) of 50-150 kohm, typically 100 kohm. In addition, some pins have specialized functions:

• PWM: Pins 2 to 13 Provide 8-bit PWM output with the analogWrite() function. the resolution of the PWM can be changed with the analogWriteResolution() function.

• SPI: ICSP header These pins support SPI communication using the SPI library. The SPI pins are broken out on the ICSP header, which is physically compatible with the Uno, Leonardo and Mega2560. The ICSP header can be used only to communicate with other SPI devices, not for programming the SAM3X with the In-Circuit-Serial-Programming technique. The SPI of the Due has also advanced features that can be used with the Extended SPI methods for Due.

• DA0 and DA1 These pins provides two real analog outputs with 12-bits of resolution (4096 levels). These pins can be used to create an audio output, with the Audio library.

• CAN: CAN RX0 & TX0 These pins support the CAN communication but are not not yet supported by Arduino APIs.

• LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH, the LED is on, when the pin is LOW, it's off. It is also possible to dim the LED because the digital pin 13 is also a PWM outuput.

The Due has 12 analog inputs, each of which provide 12 bits of resolution (i.e. 4096 different values). By default the resolution of the readings is set at 10 bits, for compatibility with other Arduino boards. It is possible to change the resolution of the ADC with analogReadResolution(). The Due's analog inputs pins measure from ground to 3.3 volts, though is it possible to change the upper end of their range using the AREF pin and analogReference() function.

Other pins on the board:

The Arduino Due has a number of facilities for communicating with a computer, another Arduino or other microcontrollers and different devices like phones, tablets, cameras and so on. The SAM3X provides one hardware UART, connected to RX0 and TX0, and three hardware USARTs for TTL (3.3V) serial communication. Serial0 on pins RX0 and TX0 also provides the Serial-to-USB communication used for programming the board through the ATmega16U2 microcontroller that provides a virtual COM port to software on the computer (Windows machines will need a .inf file, but OSX and Linux machines will recognize the board as a COM port automatically.) The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the ATmega16U2 chip and USB connection to the computer (but not for serial communication on pins 0 and 1).

The SAM3X has 512 KB (2 blocks of 256 KB) of flash memory for storing code. The bootloader is preburned in factory from Atmel and is stored in a dedicate ROM memory. The available SRAM is 98 KB (64 + 32 KB). For saving data or variables to maintain when the Due is powered off there is a 2Mbit (250 Kbyte) external DataFlash accessible via SPI or with the LIBRARY.

The Arduino Due is a microcontroller board based on the Atmel SAM3X8E ARM Cortex-M3 CPU (datasheet). It has 54 digital input/output pins (of which 16 can be used as PWM outputs), 12 analog inputs, 4 UARTs (hardware serial ports), a 84 MHz crystal oscillator, two USB connections, a power jack, an ICSP header, a JTAG header, and a reset button. The maximum voltage that the I/O pins can provide or tolerate is 3.3V. Providing higher voltages, like 5V to an input pin could damage the board. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Due is compatible with all the shields that can work at 3.3V and are compliant with the 1.0 Arduino pinout. Most of them are designed for the other Arduino boards, especially for the Uno.

The Due has the 1.0 pinout, which consist in:

• TWI interface SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields that has that pin to adapt to the voltage provided from the board. This to provide that the shield is compatible with the 3.3 V board like the Due and with the other board with the AVRs which operate with 5V. The second one is a not connected pin, that is reserved for future purposes.
• Atmega 16U2 for the USB-to-Serial conversion and for manage the reset and erase procedure.

• 3.3V. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 800 mA. This regulator also provide the power supply to the SAM3X microcontroller.

• IOREF. This pin on the Arduino board provide the voltage reference with which the microcontroller on-board operates. The shields that adopts the IOREF pin are able to select the power source or enable voltage translators on the outputs for working with the 5V or 3.3V different boards.

• SPI: ICSP header These pins support SPI communication using the SPI library. The SPI pins are broken out on the ICSP header, which is physically compatible with the Uno, Leonardo and Mega2560. The ICSP header could be used only to communicate with other SPI devices not for programming the SAM3X with the In-Circuit-Serial-Programming technique. The SPI of the Due has also advanced features that can be used with the Extended SPI methods for Due.

• DA0 and DA1 These pins provides two real analog outputs with 12-bits of resolution (4096 levels). These pins, for example, could be used to create an audio output, like was done in the Audio library.

The Arduino Due is a microcontroller board based on the Atmel SAM3X8E ARM Cortex-M3 CPU (datasheet). It has 54 digital input/output pins (of which 16 can be used as PWM outputs), 12 analog inputs, 4 UARTs (hardware serial ports), a 84 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, a JTAG header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Due is compatible with most shields designed for the other Arduino boards, especially for the Uno, or previous ones.

The Due is the first Arduino board based on a 32-bit ARM core microcontroller.

Schematic, Reference Design & Pin Mapping

EAGLE files: arduino-Due-reference-design.zip

Schematic: arduino-Due-schematic.pdf

Pin Mapping: PinMapSAM3X page

The Arduino Due can be powered via the USB connection or with an external power supply. The power source is selected automatically.

The Due has the 1.0 pinout, which consist in:

• TWI interface SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields that has that pin to adapt to the voltage provided from the board. This to provide that the shield is compatible with the 3.3 V board like the Due and with the other board with the AVRs which operate with 5V. The second one is a not connected pin, that is reserved for future purposes.
• Atmega 16U2 for the USB-to-Serial conversion and for manage the reset and erase procedure.

• 5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.

• 3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 800 mA. This regulator also provide the power supply to the SAM3X microcontroller.

The SAM3X has 512 KB (2 blocks of 256 KB) of flash memory for storing code. The bootloader is preburned in factory from Atmel and is stored in a dedicate ROM memory. The available SRAM is 98 KB (64 + 32 KB).

Each of the 54 digital pins on the Due can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 3.3 volts. Each pin can provide (source) a current between 3 and 15 mA or receive (sink) a current between 6 and 9 mA and they have an internal pull-up resistor (disconnected by default) of 50-150 kohm, typical 100 kohm. In addition, some pins have specialized functions:

• Serial: 0 (RX) and 1 (TX); Serial 1: 19 (RX) and 18 (TX); Serial 2: 17 (RX) and 16 (TX); Serial 3: 15 (RX) and 14 (TX). Used to receive (RX) and transmit (TX) TTL serial data (with 3.3 V level). Pins 0 and 1 are also connected to the corresponding pins of the ATmega16U2 USB-to-TTL Serial chip.

(:if false:)

• External Interrupts: 2 (interrupt 0), 3 (interrupt 1), 18 (interrupt 5), 19 (interrupt 4), 20 (interrupt 3), and 21 (interrupt 2). These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. See the attachInterrupt() function for details.

(:ifend:)

• PWM: 2 to 13 Provide 8-bit PWM output with the analogWrite() function.

• SPI: ICSP header These pins support SPI communication using the SPI library. The SPI pins are broken out on the ICSP header, which is physically compatible with the Uno, Leonardo and Mega2560. The ICSP header could be used only to communicate with other SPI devices not for programming the SAM3X with the In-Circuit-Serial-Programming technique.

• ’’’DA0 and DA1’’’ These pins provides two real analog outputs with 12-bits of resolution (4096 levels). These pins, for example, could be used to create an audio output, like was done in the Audio library.

• CAN: CAN RX0 & TX0 These pins support the CAN communication but still not yet implemented with the Arduino APIs.

• LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off. It is also possible to dimmer the LED because the digital pin 13 is also a PWM outuput.

• TWI: 20 (SDA) and 21 (SCL) and on pins SDA1 and SCL1. Support TWI communication using the Wire library.

The Due has 12 analog inputs, each of which provide 12 bits of resolution (i.e. 4096 different values). By default the resolution of the readings is set at 10 bits, agreeing with the other Arduino boards. Analog inputs pins measure from ground to 3.3 volts, though is it possible to change the upper end of their range using the AREF pin and analogReference() function.

The Arduino Due has a number of facilities for communicating with a computer, another Arduino or other microcontrollers and other different devices like phones, tablets, cameras and so on. The SAM3X provides one hardware UART, connected to RX0 and TX0, and three hardware USARTs for TTL (3.3V) serial communication. The Serial0 on pins RX0 and TX0 also provide the Serial to USB communication used for programming the board through the ATmega16U2 microcontrolle that provides a virtual com port to software on the computer (Windows machines will need a .inf file, but OSX and Linux machines will recognize the board as a COM port automatically. The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the ATmega8U2/ATmega16U2 chip and USB connection to the computer (but not for serial communication on pins 0 and 1).

The SAM3X also supports TWI and SPI communication. The Arduino software includes a Wire library to simplify use of the TWI bus; see the documentation for details. For SPI communication, use the SPI library.

The Arduino Due can be programmed with the Arduino software (download). For details, see the reference and tutorials.

The ATmega16U2 firmware source code is available in the Arduino repository. The ATmega16U2/8U2 is loaded with a DFU bootloader, which can be activated by:

• On Rev2 or later boards: there is a resistor that pulling the 8U2/16U2 HWB line to ground, making it easier to put into DFU mode. You can then use Atmel's FLIP software (Windows) or the DFU programmer (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 this user-contributed tutorial for more information.

Rather then requiring a physical press of the reset button before an upload, the Arduino Due 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 the ATmega16U2 is connected to the reset line of the Due via a 100 nanofarad 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 setup has other implications. When the SAM3X 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 bootloader is running on the SAM3X. While it is programmed 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 opened. If a sketch running on the board receives one-time configuration or other data when it first starts, make sure that the software with which it communicates waits a second after opening the connection and before sending this data.

The SAM3X contains a trace that can be cut to disable the auto-reset. The pads on either side of the trace can be soldered together to re-enable it. It's labeled "RESET-EN". You may also be able to disable the auto-reset by connecting a 110 ohm resistor from 5V to the reset line; see this forum thread for details.

The Arduino Due 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 and Shield Compatibility

The maximum length and width of the Arduino Due PCB are 4 and 2.1 inches respectively, with the USB connectors and power jack extending beyond the former dimension. Three screw holes allow the board to be attached to a surface or case. Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even multiple of the 100 mil spacing of the other pins.

The Arduino Due is designed to be compatible with most shields designed for the Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and GND pins), analog inputs 0 to 5, the power header, and ICSP header are all in equivalent locations. Further the main UART (serial port) is located on the same pins (0 and 1), as are external interrupts 0 and 1 (pins 2 and 3 respectively). SPI is available through the ICSP header on both the Mega2560 and Duemilanove / Diecimila. Please note that I²C is not located on the same pins on the Mega (20 and 21) as the Duemilanove / Diecimila (analog inputs 4 and 5).

Arduino Due

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(:cellnr colspan=2:) (:cell colspan=2:) (:cellnr colspan=2:) Arduino Due Front (:cell colspan=2:) Arduino Due Back

(:cell:) Arduino Due Front (:cell:) Arduino Due Back

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Overview

The Arduino Due is a microcontroller board based on a 32 bit ARM architecture (datasheet). It has 54 digital input/output pins (of which 14 can be used as PWM outputs), 12 analog inputs, a 84 MHz crystal oscillator, a micro USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

////////////// The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.
Revision 2 of the Uno board has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode.
Revision 3 of the board has the following new features:

• 1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible both with the board that use the AVR, which operate with 5V and with the Arduino Due that operate with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
• Stronger RESET circuit.
• Atmega 16U2 replace the 8U2.

"Uno" means one in Italian and is named 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 index of Arduino boards.

Summary

Schematic & Reference Design

EAGLE files: arduino-uno-Rev3-reference-design.zip (NOTE: works with Eagle 6.0 and newer)

Schematic: arduino-uno-Rev3-schematic.pdf

Note: The Arduino reference design can use an Atmega8, 168, or 328, Current models use an ATmega328, but an Atmega8 is shown in the schematic for reference. The pin configuration is identical on all three processors.

Power

The Arduino Uno can be powered via the USB connection or with an external power supply. The power source is selected automatically.

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's power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector.

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:

• VIN. 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, or, if supplying voltage via the power jack, access it through this pin.

• 5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.

• 3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 mA.

• GND. Ground pins.

Memory

The ATmega328 has 32 KB (with 0.5 KB used for the bootloader). It also has 2 KB of SRAM and 1 KB of EEPROM (which can be read and written with the EEPROM library).

Input and Output

Each of the 14 digital pins on the Uno can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. 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:

• Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip.

• External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. See the attachInterrupt() function for details.

• PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analogWrite() function.

• SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication using the SPI library.

• LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off.

The Uno has 6 analog inputs, labeled A0 through A5, each of which provide 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 analogReference() function. Additionally, some pins have specialized functionality:

• TWI: A4 or SDA pin and A5 or SCL pin. Support TWI communication using the Wire library.

There are a couple of other pins on the board:

• AREF. Reference voltage for the analog inputs. Used with analogReference().

• Reset. Bring this line LOW to reset the microcontroller. Typically used to add a reset button to shields which block the one on the board.

See also the mapping between Arduino pins and ATmega328 ports. The mapping for the Atmega8, 168, and 328 is identical.

Communication

The Arduino Uno has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers. The ATmega328 provides UART TTL (5V) serialese instructions]] for details.

The ATmega16U2 (or 8U2 in the rev1 and rev2 boards) firmware source code is available . The ATmega16U2/8U2 is loaded with a DFU bootloader, which can be activated by:

• On Rev1 boards: connecting the solder jumper on the back of the board (near the map of Italy) and then resetting the 8U2.
• On Rev2 or later boards: there is a resistor that pulling the 8U2/16U2 HWB line to ground, making it easier to put into DFU mode.

You can then use Atmel's FLIP software (Windows) or the DFU programmer (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 this user-contributed tutorial for more information.

Automatic (Software) Reset

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 the ATmega8U2/16U2 is connected to the reset line of the ATmega328 via a 100 nanofarad 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 bootloader can have a shorter timeout, as the lowering of DTR can be well-coordinated with the start of the upload.

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 bootloader is running on the Uno. While it is programmed 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 opened. If a sketch running on the board receives one-time configuration or other data when it first starts, make sure that the software with which it communicates waits a second after opening the connection and before sending this data.

The Uno contains a trace that can be cut to disable the auto-reset. The pads on either side of the trace can be soldered together to re-enable it. It's labeled "RESET-EN". You may also be able to disable the auto-reset by connecting a 110 ohm resistor from 5V to the reset line; see this forum thread for details.

USB Overcurrent Protection

The Arduino Uno 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 Uno PCB are 2.7 and 2.1 inches respectively, with the USB connector and power jack extending beyond the former dimension. Four screw holes allow the board to be attached to a surface or case. Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even multiple of the 100 mil spacing of the other pins.