Hear the Light: LED Sound Level Meter

1const int micPin = A0; // Pin A0 is used for the microphone input
2
3int sample; // Variable to store the current sound sample
4int maxVal = 0; // Variable to track the maximum sound level detected
5int minVal = 1023; // Variable to track the minimum sound level detected
6
7// Shift register pins
8int LatchPin = 3; // Pin 3 is connected to the LatchPin (ST_CP) of the 74HC595
9int ClockPin = 5; // Pin 5 is connected to the ClockPin (SH_CP) of the 74HC595
10int DataPin = 2; // Pin 2 is connected to the DataPin (DS) of the 74HC595
11
12// Binary patterns for the LEDs, representing different sound levels
13byte LEDs0 = 0b10000000; // LED pattern for the lowest sound level
14byte LEDs1 = 0b10000001;
15byte LEDs2 = 0b10000011; 
16byte LEDs3 = 0b10000111; 
17byte LEDs4 = 0b10001111; 
18byte LEDs5 = 0b10011111; 
19byte LEDs6 = 0b10111111; 
20byte LEDs7 = 0b11111111; // LED pattern for the highest sound level
21
22void setup() {
23  // Setting the shift register pins as outputs
24  pinMode(LatchPin, OUTPUT);
25  pinMode(ClockPin, OUTPUT);
26  pinMode(DataPin, OUTPUT);
27
28  // Setting the microphone pin as an input
29  pinMode(micPin, INPUT);
30  
31  // Starting the serial communication for debugging (optional)
32  Serial.begin(9600);
33}
34
35void loop() {
36  // Process microphone data to determine the peak-to-peak value
37  for (int i = 0; i < 100; i++) { // Take 100 samples to find the sound range
38    sample = analogRead(micPin); // Read the current sound level from the microphone
39    if (sample > maxVal) { // Update maxVal if the current sample is greater
40      maxVal = sample;
41    }
42    if (sample < minVal) { // Update minVal if the current sample is lower
43      minVal = sample;
44    }
45  }
46  
47  int peakToPeak = maxVal - minVal; // Calculate the peak-to-peak value
48
49  // Convert the peak-to-peak value to a voltage level (0-5V range)
50  float voltage = (peakToPeak * 5.0) / 1023.0;
51  
52  // Prepare to send data to the shift register by setting the latch pin low
53  digitalWrite(LatchPin, LOW);
54 
55  // Determine which LED pattern to display based on the voltage level
56  if(voltage > 2.4){ // Highest sound level
57   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs7); // Send the LED pattern for the highest sound
58   digitalWrite(LatchPin, HIGH); // Latch the data to display the LEDs
59  }
60  else if(voltage > 2.1){ // Second highest sound level
61   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs6); // Send the corresponding LED pattern
62   digitalWrite(LatchPin, HIGH); 
63  }  
64  else if(voltage > 1.8){ // Third highest sound level
65   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs5); // Send the corresponding LED pattern
66   digitalWrite(LatchPin, HIGH); 
67  }  
68  else if(voltage > 1.5){ // Medium-high sound level
69   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs4); // Send the corresponding LED pattern
70   digitalWrite(LatchPin, HIGH);     
71  }  
72 else if(voltage > 1.2){ // Medium sound level
73   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs3); // Send the corresponding LED pattern
74   digitalWrite(LatchPin, HIGH);    
75 }  
76 else if(voltage > 0.9){ // Low-medium sound level
77   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs2); // Send the corresponding LED pattern
78   digitalWrite(LatchPin, HIGH); 
79 }  
80 else if(voltage > 0.6){ // Low sound level
81   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs1); // Send the corresponding LED pattern
82   digitalWrite(LatchPin, HIGH); 
83 }  
84 else if(voltage > 0.0){ // Lowest sound level
85   shiftOut(DataPin, ClockPin, LSBFIRST, LEDs0); // Send the corresponding LED pattern
86   digitalWrite(LatchPin, HIGH); 
87 }   
88
89  // Reset maxVal and minVal for the next set of samples
90  maxVal = 0;
91  minVal = 1023;
92}