Create new example for NRF52

examples/Platforms/NRF52/NRF52_SD_Playback_I2S_Auto/NRF52_SD_Playback_I2S_Auto.ino

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+/*
+    AutoAnalogAudio streaming via DAC & ADC by TMRh20
+    Copyright (C) 2016  TMRh20 - [email protected], github.com/TMRh20
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+  Auto Analog Audio (Automatic DAC, ADC & Timer) library
+
+  Auto Analog Audio Library Information:
+  http://github.com/TMRh20
+  http://tmrh20.blogspot.com
+
+  This example automatically determines the format of WAV files & 
+  attempts to play them.
+*/
+
+#include <SPI.h>
+#include <SdFat.h>
+#include <AutoAnalogAudio.h>
+
+AutoAnalog aaAudio;
+SdFat SD;
+
+/*********************************************************/
+/* Tested with MAX98357A I2S breakout
+/* BCLK connected to Arduino D1 (p0.03)
+/* LRCK connected to Arduino D3 (p0.29)
+/* DIN  connected to Arduino D5 (p0.05)
+/* SD   connected to Arduino D6 (p1.11)
+/*********************************************************/
+float volumeControl = 0.2;
+#define BUFFER_SIZE 640
+
+void setup() {
+
+  Serial.begin(115200);
+
+  Serial.print("Init SD card...");
+  if (!SD.begin(2, 32000000)) {
+    Serial.println("init failed!");
+    return;
+  }
+  Serial.println("init ok");
+  Serial.println("Analog Audio Begin");
+  aaAudio.begin(0, 1, 1);  //Setup aaAudio using DAC and I2S
+
+  pinMode(6, OUTPUT);  //Connected to SD pin of MAX98357A
+  digitalWrite(6, HIGH);
+
+  playAudio("brick/brick24.wav");  // 24kHz @ 16-bits is about the maximum when reading from SD card
+}
+
+void loop() {
+
+  loadBuffer();
+
+
+  if (Serial.available()) {
+    char c = Serial.read();
+    if (c == '=') {
+      volumeControl += 0.1;
+    } else if (c == '-') {
+      volumeControl -= 0.1;
+      volumeControl = max(0.0, volumeControl);
+    } else if (c == 'p') {
+      playAudio("brick/brick24.wav");
+    }
+    Serial.println(volumeControl);
+  }
+}
+
+/*********************************************************/
+/* A simple function to handle playing audio files
+/*********************************************************/
+
+File myFile;
+
+void playAudio(char *audioFile) {
+
+  if (myFile) {
+    myFile.close();
+  }
+  //Open the designated file
+  myFile = SD.open(audioFile);
+
+  myFile.seek(22);
+  uint16_t var;
+  uint32_t var2;
+  myFile.read(&var, 2);   // Get channels (Stereo or Mono)
+  myFile.read(&var2, 4);  // Get Sample Rate
+  aaAudio.setSampleRate(var2, var - 1);
+
+  myFile.seek(34);
+  myFile.read(&var, 2);  // Get Bits Per Sample
+  aaAudio.dacBitsPerSample = var;
+
+  myFile.seek(44);  //Skip past the WAV header
+}
+
+void loadBuffer() {
+
+  if (myFile.available()) {
+
+    if (aaAudio.dacBitsPerSample == 8) {
+      myFile.read(aaAudio.dacBuffer, BUFFER_SIZE);  // Change this to dacBuffer16 for 16-bit samples
+      for (uint32_t i = 0; i < BUFFER_SIZE; i++) {
+        aaAudio.dacBuffer[i] *= volumeControl;
+      }
+      aaAudio.feedDAC(0, BUFFER_SIZE);  // change this to 3200 for 16-bit samples
+    } else {
+      myFile.read(aaAudio.dacBuffer16, BUFFER_SIZE);  // Change this to dacBuffer16 for 16-bit samples
+      for (uint32_t i = 0; i < BUFFER_SIZE / 2; i++) {
+        aaAudio.dacBuffer16[i] += 0x8000;
+        aaAudio.dacBuffer16[i] *= volumeControl;
+        aaAudio.dacBuffer16[i] -= 0x8000;
+      }
+      aaAudio.feedDAC(0, BUFFER_SIZE / 2);  // change this to 3200 for 16-bit samples
+    }
+
+  } else {
+    myFile.seek(44);
+  }
+}