Arduino Uno

A microcontroller based around the ATmega328P chip. The processor is clocked at 16 MHz and features 2 KB SRAM, 32 KB of program flash storage, and 1 KB of user-writable EEPROM.

With a 10-bit ADC over an operating range of 0–5 V, the analog input pins have a resolution of 4.9 mV. Digital I/O pins can supply a maximum of 20 mA.

It appears from the documentation that the serial pins (0 and 1) are internally connected to the USB interface [1]. In order to use both USB and another serial device, the SoftwareSerial library is necessary. In any case, serial operation is at TTL levels (not RS-232).

Pins A4 and A5 can also function as I2C SDA and SCL, respectively. The Wire library expects 7-bit addresses, so if given an 8-bit address, drop the least significant bit. Note also that the I2C buffer is 32 bytes; transmissions longer than this will be truncated [2].

On the Uno, ints and shorts are 2 bytes; floats and doubles are 4 bytes.