43 lines
3.2 KiB
C
43 lines
3.2 KiB
C
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#ifndef SOUNDMEMS_H
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#define SOUNDMEMS_H
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void soundmems() { // Here's where we capture sound. It provides an average, a current sample as well as a peak trigger.
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// I tried some fancier math, but never came up with anything that really worked all that well. Must . . work. . harder.
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// Local definitions
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#define sensitivity 100 // Define maximum cutoff of potentiometer for cutting off sounds.
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#define DC_OFFSET 512 // DC offset in mic signal. I subtract this value from the raw sample of a 'quiet room' test.
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#define NSAMPLES 64 // Creating an array of lots of samples for decent averaging.
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// Persistent local variables (saved for next iteration)
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static int16_t samplearray[NSAMPLES]; // Array of samples.
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static uint16_t samplesum = 0; // Sum of the last 64 samples. This had better be positive.
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static uint8_t samplecount = 0; // A rollover counter to cycle through the array.
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// Temporary local variables
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int16_t sample = 0; // Current sample. Starts with negative values, which is why it's signed.
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uint16_t potin; // Our scaled potentiometer value.
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samplepeak = 0; // Reset the global sample peak.
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potin = map(analogRead(POT_PIN), 0, 1023, 0, sensitivity); // Read the potentiometer and scale it to our sensitivity setting, which is scaled to our microphone readings.
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sample = analogRead(MIC_PIN) - DC_OFFSET; // Sample the microphone. Range will result in -512 to 512.
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sample = abs(sample); // Get the absolute value and DO NOT combine abs() into the previous line or this will break. Badly!
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if (sample < potin) sample = 0; // Filter ambient noise, which is adjustable via the potentiometer.
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samplesum += sample - samplearray[samplecount]; // Add the new sample and remove the oldest sample in the array. No 'for' loops required here for extra speed.
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sampleavg = samplesum / NSAMPLES; // Get an average.
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samplearray[samplecount] = sample; // Update oldest sample in the array with new sample. By Andrew Tuline.
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samplecount = (samplecount + 1) % NSAMPLES; // Update the counter for the array and rollover if we hit the max.
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if (sample > (sampleavg + potin) && (sample < oldsample)) samplepeak = 1; // We're on the down swing, so we just peaked.
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oldsample = sample; // We'll use oldsample globally as our 'current' sample.
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} // soundmems()
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#endif
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