Except, on the Micro, there is no actual serial bus involved in programming the Arduino, as everything is done over USB. So the TX and RX leds are driven by a couple of pins on the ATmega32U4 (see a ...

The Arduino itself, arguably, is a breakout board of sorts. It takes the ATmega chip, adds the hardware necessary to get it talking to a computer over USB, and brings all the GPIO pins out with ...