Aim of the project is to build lightweight laser/light sensor that can be mounted on quadcopter and used for gaming purposes. Sensor reads environmental light level via LDR, and sets the threshold below it. Any significant change in the light level will trigger the LED-s. Sensor will be used for the Dronosphere workshop and performance.
It's recommended to test the circuit on Arduino first. You will have serial monitor available and will be able to see LDR values and further fine-tune the code or components.
const int LDR = A0; // analog pin to which LDR is connected const int LED = 13; // pin to which LED is connected const int sensitivity = 50; // setting the light sensitivity int LDRValue = 0; // variable to store LDR values int threshold; // light sensitivity threshold float voltage; // variable to store voltage void setup() { Serial.begin(9600); // start the serial monitor with 9600 baud pinMode(LED, OUTPUT); // configure LED pin to behave as output threshold = analogRead(LDR) - sensitivity; // set light sensitivity threshold } void loop() { LDRValue = analogRead(LDR); // read LDR value Serial.print("Raw Rate: "); // print text Serial.println(LDRValue); // print value to serial monitor float voltage = LDRValue * (5.0 / 1023.0); // convert analog reading (which goes from 0-1023) to a voltage (0-5V) Serial.print("Voltage: "); Serial.println(voltage); Serial.println(); if (LDRValue <= threshold) // if the LDR reading is lower than the threshold { for (int i = 0; i <= 50; i++) { // blink LEDs digitalWrite(LED, HIGH); delay(50); digitalWrite(LED, LOW); delay(50); } delay(1000); threshold = analogRead(LDR) - sensitivity; // set light sensitivity threshold delay(1000); } else { digitalWrite(LED, LOW); } }
Now that we have tested everything, we can port it to ATtiny microcontroller (tested with ATtiny45, ATtiny85), which has significantly smaller profile, its cheaper and works on 3V.
#define LDR A1 // analog pin to which LDR is connected #define LED 1 // pin to which LED is connected const int sensitivity = 40; // setting the light sensitivity int LDRValue = 0; // variable to store LDR values int threshold; // light sensitivity threshold void setup() { pinMode(LED, OUTPUT); // configure LED pin to behave as output threshold = analogRead(LDR) - sensitivity; // set light sensitivity threshold } void loop() { LDRValue = analogRead(LDR); // read LDR value if (LDRValue <= threshold) // if the LDR reading is lower than the threshold { for (int i = 0; i <= 50; i++) { // blink LEDs digitalWrite(LED, HIGH); delay(50); digitalWrite(LED, LOW); delay(50); } delay(1000); threshold = analogRead(LDR) - sensitivity; // set light sensitivity threshold delay(1000); } else { digitalWrite(LED, LOW); } }
Cover the LDRs with semi-transparent material to act as light diffuser. Doing this will make sensor sensitive over bigger area. Also leave enough space between LDRs and diffuser for light to spread. You can use ping pong ball, or ball from vending machine.