lamp.c

//set the faces
#define SENSOR_FACE FACE_7
#define LIGHT_FACE FACE_2
#define LIGHT2_FACE FACE_6

int lampState; //State of the lamp (on or off)
#define OFF 0 //lamp is off
#define ON 1 //lamp is on

bool WaitingToReset; //Flag to denote whether a state change can occur
#define SENSOR_THRESHOLD 30 //when the sensor value exceeds this value (out of 255) the lamp will toggle state
#define SENSOR_HYSTERESIS 10 //When the sensor drops this much below SENSOR_THRESHOLD the lamp will be eligible to change state again.

void setup()
{
	//set  face directions
	set_face_state(SENSOR_FACE, INPUT);
	set_face_state(LIGHT_FACE, OUTPUT);
	set_face_state(LIGHT2_FACE, OUTPUT);

	lampState = OFF;
	WaitingToReset = false;
}
void loop()
{
	uint8_t sensorValue = get_face_value(SENSOR_FACE);

	if (WaitingToReset == false && sensorValue > SENSOR_THRESHOLD){
		WaitingToReset = true;
		if (lampState == OFF){
			lampState = ON;
			set_face_value(LIGHT_FACE, 255);
			set_face_value(LIGHT2_FACE, 255);
		} 
		else { //if lampState == ON
			lampState = OFF;
			set_face_value(LIGHT_FACE, 0);
			set_face_value(LIGHT2_FACE, 0);
		}
	}
	if (sensorValue < SENSOR_THRESHOLD - SENSOR_HYSTERESIS){
		WaitingToReset = false;
	}
}