Arduino Uno

Robert Seastrom rs at
Thu Oct 25 15:02:37 CDT 2012

There is an interesting detail about the Uno that some folks aren't aware of.

The Uno has an ATmega8U2 and the Uno r3 has an ATmega16U2 on board.  These are both in lieu of the FTDI FT232R as found on several previous generations of Arduinos.  It's that tiny chip that's next to the USB jack.

OK, why should you care?  The FT232R looks like a serial port, over USB.  It's how you load code into the device, talk to an ASCII console, etc.  The ATmega(8|16)U2 looks like a serial port too (a much faster one) but that's just the start - since it is a general USB interface chip it can allow the Arduino to be a Human Interface Device (HID), such as a joystick, mouse, keyboard, etc. to something else that is on the same USB bus.

Uses for this capability are left as an exercise to the reader.

Also, Amazon has 'em for $21.95 and eligible for Amazon Prime.  Depending on your circumstances this may be much less expensive than a trip to Micro Center.


On Oct 24, 2012, at 4:25 PM, Karl W4KRL wrote:

> Micro Center in Fairfax has the Arduino Uno rev. 3 board for $19.95. Here is a great way to get started with Arduino. Spark Fun and Maker Shed sell this for $30 to $35.
> 73 Karl W4KRL
> Specs:
> Microcontroller                 ATmega328
> Operating Voltage           5V
> Input Voltage (recommended) 7-12V
> Input Voltage (limits)     6-20V
> Digital I/O Pins                   14 (of which 6 provide PWM output)
> Analog Input Pins             6
> DC Current per I/O Pin   40 mA
> DC Current for 3.3V Pin 50 mA
> Flash Memory                   32 KB (ATmega328) of which 0.5 KB used by bootloader
> SRAM                                    2 KB (ATmega328)
> EEPROM                              1 KB (ATmega328)
> Clock Speed                       16 MHz
> “The Arduino Uno is a microcontroller board based 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. 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.”
> See
> Nice comparison of the Uno with earlier versions:
> Some good ham projects using the Arduino:
> <image003.jpg>
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