i want to know code for counting the flashes of LEDs and display no. of flashes in particular time given.by using LDR. basically i tried it with interrupts but i'm not getting it,so please help in this regard.

  • If you post the code of your attempt, we might be able to help you. – uint128_t Mar 1 '16 at 15:39

An hardware solution could be achieved by putting a photodiode or a photoresistance near the flashing LED. Connect it to a pin that supports external interrupt and you're done. With a bit more circuitry you can ensure that the value on the pin doesn't oscillate: put a Schmit Trigger after the photodiode or resitance with its output on the input pin.

| improve this answer | |
  • The Arduino Uno already has Schmitt triggers on all its digital inputs. C.f. figure 14.2 on page 76 of the ATmega328P datasheet. – Edgar Bonet Mar 2 '16 at 9:31

LDRs only give an analog output, proportional to the amount of light.

To make it give a HIGH and LOW value, you have to tweak the other resistor used in the voltage divider.

Alternatively you could use analogRead and add a threshold value in your code.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.