// Connect an I2S DAC or amp (like the UDA1334A) to the Arduino Zero
// and play back simple sine, sawtooth, triangle, and square waves.
// Makes your Zero sound like a NES!
//
// NOTE: The I2S signal generated by the Zero does NOT have a MCLK /
// master clock signal. You must use an I2S receiver that can operate
// without a MCLK signal (like the UDA1334A).
//
// For an Arduino Zero / Feather M0 connect it to you I2S hardware as follows:
// - Digital 0 -> I2S LRCLK / FS (left/right / frame select clock)
// - Digital 1 -> I2S BCLK / SCLK (bit / serial clock)
// - Digital 9 -> I2S DIN / SD (data output)
// - Ground
//
// Released under a MIT license: https://opensource.org/licenses/MIT
#include "Adafruit_ZeroI2S.h"
#define SAMPLERATE_HZ 44100 // The sample rate of the audio. Higher sample rates have better fidelity,
// but these tones are so simple it won't make a difference. 44.1khz is
// standard CD quality sound.
#define AMPLITUDE ((1<<29)-1) // Set the amplitude of generated waveforms. This controls how loud
// the signals are, and can be any value from 0 to 2**31 - 1. Start with
// a low value to prevent damaging speakers!
#define WAV_SIZE 256 // The size of each generated waveform. The larger the size the higher
// quality the signal. A size of 256 is more than enough for these simple
// waveforms.
// Define the frequency of music notes (from http://www.phy.mtu.edu/~suits/notefreqs.html):
#define C4_HZ 261.63
#define D4_HZ 293.66
#define E4_HZ 329.63
#define F4_HZ 349.23
#define G4_HZ 392.00
#define A4_HZ 440.00
#define B4_HZ 493.88
// Define a C-major scale to play all the notes up and down.
float scale[] = { C4_HZ, D4_HZ, E4_HZ, F4_HZ, G4_HZ, A4_HZ, B4_HZ, A4_HZ, G4_HZ, F4_HZ, E4_HZ, D4_HZ, C4_HZ };
// Store basic waveforms in memory.
int32_t sine[WAV_SIZE] = {0};
int32_t sawtooth[WAV_SIZE] = {0};
int32_t triangle[WAV_SIZE] = {0};
int32_t square[WAV_SIZE] = {0};
// Create I2S audio transmitter object.
Adafruit_ZeroI2S i2s;
#define Serial Serial
void generateSine(int32_t amplitude, int32_t* buffer, uint16_t length) {
// Generate a sine wave signal with the provided amplitude and store it in
// the provided buffer of size length.
for (int i=0; i<length; ++i) {
buffer[i] = int32_t(float(amplitude)*sin(2.0*PI*(1.0/length)*i));
}
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