Uno R3 Development Board Official Version Compatible With Arduino Control Atmega328p Microcontroller Electronic Module
UNO R3 is 2012 new type a is easy to use open source controller, hardware and no big change, compared with UNO biggest difference is that the USB serial interface circuit, a switch is a ATMega16U2 of single-chip microcomputer, it also improved the cost, the software part as before, there is no big changes.
1.Stitching changes: beside the AREF sutural added two I2C pins (SDA and SCL, only Analog 4 and 5 of the copy, not extra I2C interface), in addition, beside the RESET also added two pins, one is IOREF, can let the extension plate to plate load voltage, the stitching just tell extension board the on-board voltage is how many (such as UNO is 5 v, can be seen as power supply pins copy, does not provide a level), the other one is after treated with placeholder pins. SUNLEPHANT
2. The more stable the RESET circuit. RESET button position is changed, moved to near the USB interface of voids, more convenient.
3. ATmega16U2 instead of 8 u2, this does not mean that there are 16 k flash R3 can make your code run faster, the update to serve is the USB interface chip, it make UNO can simulate USB HID in theory, such as the MIDI/Joystick/the rid_device_info_keyboard.