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libraries/audio-tools/examples/examples-communication/serial/mp3-xon-xoff/receive-mp3/receive-mp3.ino

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+
+/**
+ * @file receive-mp3.ino
+ * @brief Example of receiving an mp3 stream over serial and playing it over I2S
+ * using the AudioTools library.
+ * The processing implements a xon-xoff flow control over Serial. We
+ * process the data receiving in a separate task and the playback in the main
+ * loop.
+ */
+
+#include "AudioTools.h"
+#include "AudioTools/AudioCodecs/CodecMP3Helix.h"
+#include "AudioTools/AudioLibs/AudioBoardStream.h"
+#include "AudioTools/Concurrency/RTOS.h"
+
+// xon/xoff flow control
+const char xon = 17;
+const char xoff = 19;
+const int min_percent = 10;
+const int max_percent = 90;
+
+AudioBoardStream i2s(AudioKitEs8388V1);  // final output of decoded stream
+MP3DecoderHelix helix;
+EncodedAudioStream dec(&i2s, &helix);  // Decoding stream
+// queue
+BufferRTOS<uint8_t> buffer(0);
+QueueStream<uint8_t> queue(buffer);
+// copy
+StreamCopy copierFill(queue, Serial1);
+StreamCopy copierPlay(dec, queue);
+
+Task task("mp3-copy", 10000, 1, 0);
+
+void setup() {
+  Serial.begin(115200);
+  AudioLogger::instance().begin(Serial, AudioLogger::Info);
+
+  Serial0.begin(115200);
+
+  // set up buffer here to allow PSRAM usage
+  buffer.resize(1024 * 10);  // 10kB buffer
+  queue.begin(50);           // start when half full
+
+  // setup i2s
+  auto config = i2s.defaultConfig(TX_MODE);
+  i2s.begin(config);
+
+  // setup decoder
+  dec.begin();
+
+  // start fill buffer copy task
+  task.begin([]() {
+    copierFill.copy();
+    // data synchronization to prevent buffer overflow
+    if (buffer.levelPercent() >= max_percent) {
+      Serial1.write(xoff);  // stop receiving
+      Serial1.flush();
+    } else if (buffer.levelPercent() <= min_percent) {
+      Serial1.write(xon);  // start receiving
+      Serial1.flush();
+    }
+  });
+}
+
+void loop() { copierPlay.copy(); }

libraries/audio-tools/examples/examples-communication/serial/mp3-xon-xoff/send-mp3/send-mp3.ino

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+
+/**
+ * @file send-mp3.ino
+ * @brief Example of sending an mp3 stream over Serial the AudioTools library.
+ * We use xon/xoff to control the flow of the data.
+ * I am using an ESP32 Dev Module for the test with the pins TX=17 and RX=16.
+ */
+
+#include "AudioTools.h"
+#include "AudioTools/Communication/AudioHttp.h"
+
+URLStream url("ssid", "password");  // or replace with ICYStream to get metadata
+StreamCopy copier(Serial1, url);         // copy url to decoder
+// xon/xoff flow control
+const char xon = 17;
+const char xoff = 19;
+bool is_active = false;
+
+void setup() {
+  Serial.begin(115200);
+  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Error);
+
+  // setup serial data sink
+  Serial2.begin(115200);
+
+  // mp3 radio
+  url.begin("http://stream.srg-ssr.ch/m/rsj/mp3_128", "audio/mp3");
+}
+
+// Determine if we can send data from the flow control sent by the receiver
+bool isActive() {
+  char c = Serial2.read();
+  switch (c) {
+    case xon:
+      is_active = true;
+      break;
+    case xoff:
+      is_active = false;
+      break;
+  }
+  return is_active;
+}
+
+void loop() {
+  if (isActive()) {
+    copier.copy();
+  }
+}