Summary of Programming the Arduino I/O pins
The Arduino Uno is a reference microcontroller board based on the ATmega328, featuring 14 digital I/O pins, 6 analog inputs, and a 16 MHz resonator. It connects via USB or power adapter without needing an FTDI chip, utilizing an Atmega16U2 for USB-to-serial conversion. Revision 3 added SDA/SCL pins, a stronger reset circuit, and IOREF for shield compatibility. The board serves as the standard model for the Arduino platform.
Parts used in the Arduino Uno:
- ATmega328 microcontroller
- Atmega16U2 (or Atmega8U2)
- 16 MHz ceramic resonator
- USB connection
- Power jack
- ICSP header
- Reset button
- SDA and SCL pins
- IOREF pin
Overview
The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). 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. 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.
Introduction to the Arduino Microcontroller
Part 1: Programming Arduino Output
Part 2: Programming Arduino Input
Part 3: Arduino Analog to Digital Conversion
Part 4: Using Arduino Pulse-Width-Modulation
For more detail visit: Programming the Arduino I/O pins
- How does the Arduino Uno connect to a computer?
You can connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery. - What microcontroller is the Arduino Uno based on?
The board is based on the ATmega328 microcontroller. - Does the Arduino Uno use an FTDI USB-to-serial driver chip?
No, it does not use the FTDI chip; instead, it features the Atmega16U2 programmed as a USB-to-serial converter. - What new features were added in Revision 3 of the board?
Revision 3 added SDA and SCL pins, a stronger RESET circuit, and replaced the 8U2 with the Atmega 16U2. - What is the purpose of the IOREF pin?
The IOREF allows shields to adapt to the voltage provided from the board, ensuring compatibility with both 5V and 3.3V systems. - Why was the board named Uno?
Uno means one in Italian and was named to mark the upcoming release of Arduino 1.0. - Can the Arduino Uno be powered by a battery?
Yes, you can power it with a battery or an AC-to-DC adapter in addition to a USB cable. - How many digital input/output pins does the Arduino Uno have?
It has 14 digital input/output pins, of which 6 can be used as PWM outputs.
