What if multiple lamp groups need to be controlled in an existing single lamp group (Multiway switching circuit) situation.? The cabling (1 line – hot - wire and two - nonhot - wires) between switch(es) and the lamp group is existent, buit-in walls and/or ceilings in most cases and this cabling is not possible to be modified or extended. This circuit offers a safe and flexible possibility to control more than 1 lamp group by re-using of a part of the existing cabling (only 2 wires between switches and lamps required) and replacing (all) the switches by NC pushbuttons. The circuit is based on an Attiny85 which can have up to 6 GPIO’s. With the presented solution, up to 3 lamp groups could be controlled. One of the GPIO’s will be used as trigger input (is always required as a single control input), one is used for Reset and one for buzzer control. The buzzer control could be skipped, making it possible to control 4 lamp groups. If the Reset can also be ‘sacrificed’, a 5Th lamp group could be controlled, though this is not recommended, since this requires setting of fuses and the Reset capability can only be recovered afterwards by High Voltage programming.