From 70eb84943b337505aaa9c4fa94b211821cd06e5a Mon Sep 17 00:00:00 2001
From: Mark Washeim <blueprint@poetaster.de>
Date: Tue, 9 Apr 2024 13:18:33 +0200
Subject: [PATCH] Add: provide a simple I2S external DAC example for two common
 DAC chips/boards

---
 .../PCM5102_MAX98357A_I2S_stereo_16bits.ino   | 77 +++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 examples/13.External_Audio_Output/PCM5102_MAX98357A_I2S_stereo_16bits/PCM5102_MAX98357A_I2S_stereo_16bits.ino

diff --git a/examples/13.External_Audio_Output/PCM5102_MAX98357A_I2S_stereo_16bits/PCM5102_MAX98357A_I2S_stereo_16bits.ino b/examples/13.External_Audio_Output/PCM5102_MAX98357A_I2S_stereo_16bits/PCM5102_MAX98357A_I2S_stereo_16bits.ino
new file mode 100644
index 000000000..4a280ca2a
--- /dev/null
+++ b/examples/13.External_Audio_Output/PCM5102_MAX98357A_I2S_stereo_16bits/PCM5102_MAX98357A_I2S_stereo_16bits.ino
@@ -0,0 +1,77 @@
+
+/*  Example of simple and stereo synthesis via I2S for the RP2040. Tested with a Pi Pico.
+
+    using Mozzi sonification library and an external dual DAC PT8211 (inspired by: https://sparklogic.ru/code-snipplets/i2s-example-code.html)
+    using an user-defined audioOutput() function.
+
+    This example has been tested with the PCM5102 from Texas Instruments as found on boards configured as shown here: https://github.com/dwhinham/mt32-pi/wiki/GY-PCM5102-DAC-module
+
+    This example also works unmodified with Max98357A I2S amplifier boards.
+
+
+    Circuit: 
+    
+    I2S DAC   //  Connect to:
+    -------       -----------
+    Vdd           V+
+    BCK           20 
+    WS/LCK        21           
+    DIN           22
+    GND           GND
+    L/R           to audio outputs
+
+    Mozzi documentation/API
+    https://sensorium.github.io/Mozzi/doc/html/index.html
+
+    Mozzi help/discussion/announcements:
+    https://groups.google.com/forum/#!forum/mozzi-users
+
+    Tim Barrass 2012, CC by-nc-sa.
+    T. Combriat 2020, CC by-nc-sa.
+*/
+
+// before including Mozzi.h, configure external audio output mode:
+#include "MozziConfigValues.h"  // for named option values
+#define MOZZI_AUDIO_CHANNELS MOZZI_STEREO 
+#define MOZZI_AUDIO_MODE MOZZI_OUTPUT_I2S_DAC
+// all of these are the defaults on RP2040 outputting on I2S, anyway, thus commented
+#define MOZZI_AUDIO_BITS 16
+#define MOZZI_I2S_PIN_BCK 20
+#define MOZZI_I2S_PIN_WS (MOZZI_I2S_PIN_BCK+1) // CANNOT BE CHANGED, HAS TO BE NEXT TO pBCLK, i.e. default is 21
+#define MOZZI_I2S_PIN_DATA 22
+
+// End I2S related config
+
+#define CONTROL_RATE 256 // Hz, powers of 2 are most reliable
+#include <Mozzi.h>
+#include <Oscil.h>
+#include <tables/cos2048_int8.h> // table for Oscils to play
+
+// Synthesis part
+Oscil<COS2048_NUM_CELLS, AUDIO_RATE> aCos1(COS2048_DATA);
+Oscil<COS2048_NUM_CELLS, AUDIO_RATE> aCos2(COS2048_DATA);
+Oscil<COS2048_NUM_CELLS, CONTROL_RATE> kEnv1(COS2048_DATA);
+Oscil<COS2048_NUM_CELLS, CONTROL_RATE> kEnv2(COS2048_DATA);
+
+void setup() {
+  aCos1.setFreq(440.f);
+  aCos2.setFreq(220.f);
+  kEnv1.setFreq(0.25f);
+  kEnv2.setFreq(0.30f);
+  startMozzi(CONTROL_RATE);
+}
+
+// Carry enveloppes
+int env1, env2;
+void updateControl() {
+  env1 = kEnv1.next();
+  env2 = kEnv2.next();
+}
+
+AudioOutput_t updateAudio() {
+  return StereoOutput::from16Bit(aCos1.next() * env1,aCos2.next() * env2);
+}
+
+void loop() {
+  audioHook();
+}