I need to convert the output of the microphone into dB and apply a spectrum analysis. I'm using Adafruit MEMS microphone SPH0645LM4H with Arduino Mkr1000.
I am currently working with the ArduinoSound library, however there are couple things that I do not understand.
SPH0645LM4H microphone's output is 24 bits with 18 precision.
Arduino Sound library outputs 32 bits, so I can not get a true output since MEMs microphone and the library does not match in this sense.
Do you know how can I change this bit value in the library to match it with to microphone?
It would be great If you could help me with this problem, thanks.
Grumpy_Mike:
Take the microphone output and shift it to the left four times.
inputToFFT = microphone << 4;
This is the code I used, which line should be changed?
Circuit:
Arduino/Genuino Zero, MKRZero or MKR1000 board
ICS43432:
GND connected GND
3.3V connected 3.3V (Zero) or VCC (MKR1000, MKRZero)
WS connected to pin 0 (Zero) or pin 3 (MKR1000, MKRZero)
CLK connected to pin 1 (Zero) or pin 2 (MKR1000, MKRZero)
SD connected to pin 9 (Zero) or pin A6 (MKR1000, MKRZero)
#include <ArduinoSound.h>
// sample rate for the input
const int sampleRate = 12800;
// size of the FFT to compute
const int fftSize = 128;
// size of the spectrum output, half of FFT size
const int spectrumSize = fftSize / 2;
// array to store spectrum output
int spectrum[spectrumSize];
// create an FFT analyzer to be used with the I2S input
FFTAnalyzer fftAnalyzer(fftSize);
void setup() {
// Open serial communications and wait for port to open:
// A baud rate of 115200 is used instead of 9600 for a faster data rate
// on non-native USB ports
Serial.begin(115200);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
// setup the I2S audio input for the sample rate with 32-bits per sample
if (!AudioInI2S.begin(sampleRate, 32)) {
Serial.println("Failed to initialize I2S input!");
while (1); // do nothing
}
// configure the I2S input as the input for the FFT analyzer
if (!fftAnalyzer.input(AudioInI2S)) {
Serial.println("Failed to set FFT analyzer input!");
while (1); // do nothing
}
}
void loop() {
// check if a new analysis is available
if (fftAnalyzer.available()) {
// read the new spectrum
fftAnalyzer.read(spectrum, spectrumSize);
// print out the spectrum
for (int i = 0; i < spectrumSize; i++) {
Serial.print((i * sampleRate) / fftSize); // the starting frequency
Serial.print("\t"); //
Serial.println(spectrum*); // the spectrum value*
This is the code I used, which line should be changed?
Well it is not really a program as such, it is just a piece of code that calls two functions. These functions are implemented in libraries so you would would have to alter the code in those libraries.