95 lines
2.2 KiB
Arduino
95 lines
2.2 KiB
Arduino
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// Basic demo for configuring the MCP4728 4-Channel 12-bit I2C DAC
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#include <Adafruit_MCP4728.h>
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#include <Wire.h>
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Adafruit_MCP4728 mcp;
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// 1 3 5 7 hexany log2
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float hexany[] = { 0.0, 0.12928301694496647, 0.32192809488736235, 0.3923174227787603, 0.5849625007211562, 0.8073549220576041, 0.9068905956085185 };
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float tuning[7];
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int pitch[] = { 0, -1, 1, 2, -1, 3, -1, 4, 5, -1, 6, 5, -1, 3, -1, 1 };
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float dur[] = { 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5 };
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float gate = 0.5;
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int bpm = 125;
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float beat_s = 60.0 / (float)bpm;
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int beat_m = round(1000.0 * beat_s);
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float voltrange = 5.0; // measured this, probably not accurate
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float octave = 4096.0 / voltrange; // number of DAC steps in an octave
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float mod_b = 3.141592653589793 / 4.0;
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int s;
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bool noteon = false;
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long play_t;
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long release_t;
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long last_t;
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long init_t;
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void setup(void) {
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Serial.begin(115200);
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while (!Serial)
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delay(10); // will pause Zero, Leonardo, etc until serial console opens
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if (!mcp.begin(0x64)) {
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Serial.println("Failed to find MCP4728 chip");
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while (1) {
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delay(10);
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}
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Serial.println("MCP4728 initialised");
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}
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mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
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float n0 = 0;
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for( int i = 0; i < 7; i++ ) {
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tuning[i] = round(n0 + octave * hexany[i]);
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}
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s = 0;
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release_t = 0;
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play_t = 0;
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last_t = millis();
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init_t = last_t;
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}
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void loop() {
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long now = millis();
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if( noteon ) {
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if( now - last_t > release_t ) {
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noteOff();
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last_t = now;
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play_t = round(beat_m * dur[s] * (1.0 - gate));
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noteon = false;
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s += 1;
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if( s > 15 ) {
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s = 0;
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}
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}
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} else {
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if( now - last_t > play_t ) {
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noteOn(pitch[s]);
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last_t = now;
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release_t = round(beat_m * dur[s] * gate);
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noteon = true;
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}
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}
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// sychronise this better
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long mod_t = (now - init_t);
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float mod = 0.5 + 0.5 * sin(mod_b * (float)mod_t / (float)beat_m);
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mcp.setChannelValue(MCP4728_CHANNEL_C, round(4095.0 * mod));
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}
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void noteOn(int note) {
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if( note > -1 ) {
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mcp.setChannelValue(MCP4728_CHANNEL_A, tuning[note]);
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mcp.setChannelValue(MCP4728_CHANNEL_B, 4095);
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}
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}
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void noteOff() {
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mcp.setChannelValue(MCP4728_CHANNEL_B, 0);
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}
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