Week 10: Digital (Slide Switch) and Analog (Sound Sensor)

Concept

I wanted to make a lightning system where sound controls the brightness. For my digital sensor, I used a slide switch to turn the LEDs on and off. As for my analog sensor, I used a sound sensor where every time it detects a sound, the LEDs get dimmer. I’m quite interested in sound-activated lights and even though it didn’t come with the kit, I still wanted to give it a try and I got the KY-037 from Amazon.

Full Code | Video Demo | Schematics

Code that I’m proud of

int soundValue = analogRead(soundPin);
 int change = abs(soundValue - 512);

 if (change > threshold) {
   brightness = brightness - 50; // drop brightness by 50 each sound
   Serial.println("Lowering brightness.."); // debug to make sure sound is going through and brightness lowering
   delay(200);
 }

I’m proud of this part because I had to actually understand what the sound sensor was giving me. I thought it would just tell me loud or quiet (HIGH/LOW), but it outputs a number between 0 and 1023 and in silence it sits around 512 (which is about half of that range). I also added the Serial.println myself because I had no idea if claps were even registering so I wanted to confirm it was working in the Serial Monitor before trusting the LEDs and as reassurance.

How this was made

I started with the slide switch wired to pin 2 with a 10kΩ pull-down resistor to GND, the reason for the higher Ω used was to prevent the pin from floating and giving random readings when the switch is open. When it reads LOW, both LEDs turn off and brightness resets to 255 (maximum brightness) so it starts fresh every time. I had to learn how the sound sensor worked and wired it myself. It outputs a continuous number between 0 and 1023 of the volume, sitting around 512 (mid-range value) in silence, and every loop the code reads that value, subtracts 512, and takes the absolute value to get the amplitude. If that crosses my threshold of 70 the brightness drops by 50. I had a problem with sensitivity at first as it kept triggering on background noise or missing claps and I found out that the module has a small dial you adjust with a screwdriver. I also added Serial.println debug line so I could confirm in the Serial Monitor that claps were actually registering before trusting the LEDs. The two LEDs on pins 9 and 10 each have a 330Ω resistor to GND and receive the brightness value through analogWrite using PWM.

Reflection & Future Improvements

This was quite a challenging assignment because I heavily insisted on using a sound sensor. Even though the sound sensor was new to me and not something we covered in class, I was able to apply a lot of the analog concepts we already learned (things like analogRead, analogWrite, and PWM) and it translated over and made it easier to grasp. I went back to the class notes and a few tutorials online (referenced below) to piece it together. If I were to keep going I’d add more brightness steps so the dimming feels smoother, and I’d revisit an earlier idea where the two LEDs go in opposite directions where one dims while the other brightens based on the same concept of having live sound adjusts that. Nevertheless, I’m happy with my output and how it turned out.