Description
UNO R3 is an easy-to-use open-source controller newly launched in 2012. Compared with UNO, there is no major change in hardware. The big difference lies in the USB-to-serial circuit part. Instead, it uses an ATMega16U2 single-chip microcomputer, so the cost is also somewhat different. , The software part is the same as before, without major changes.
Function:
1. Pin changes: Two I2C pins are added next to the AREF pin (SDA and SCL are just copies of Analog 4 and 5, not an additional I2C interface), in addition, two pins are added next to RESET, one is IOREF, Can make the expansion board adapt to the onboard voltage, this pin only tells the current onboard voltage of the expansion board (for example, UNO is 5V, which can be regarded as a copy of the power pin, and does not provide level pull-up), and the other is for the future Placeholder pins to be used.
2. More stable RESET circuit. The position of the RESET button has also changed, and it has been moved to the corner of the board close to the USB interface, making it easier to press.
3. ATmega16U2 replaces 8U2. This does not mean that R3 with 16K flash can make your code run faster. This update is for the USB interface chip. In theory, it allows UNO to simulate USB HID, such as MIDI/ Joystick/Keyboard.