The HobbyKing KK 2.0 Flight Control Board is a inexpensive option for controlling a multi-rotor craft. Its purpose is to stabilize the aircraft during flight. To do this it takes the signal from the three on board gyros (roll, pitch and yaw) then passes the signal to the Atmega324PA IC. The Atmega324PA IC unit then processes these signals according the users selected firmware and passes control signals to the installed Electronic Speed Controllers (ESCs). These signals instruct the ESCs to make fine adjustments to the motors rotational speed which in turn stabilizes your multi-rotor craft.
The HobbyKing KK2.0 Multi-Rotor control board also uses signals from your radio systems receiver (Rx) and passes these signals to the Atmega324PA IC via the ail, ele, thr and rud inputs. Once this information has been processed the IC will send varying signals to the ESCs which in turn adjust the rotational speed of each motor to induce controlled flight (up, down, backwards, forwards, left, right, yaw).