In the last Blogs I presented a File Based Versatile MP3 Player and later a A Versatile but Simple Arduino Streaming MP3 Player using my Arduino Audio Tools Library.

In this Blog, I will demonstrate how easy it is to convert it into a AAC player. I also show how to control the volume.
So far I was usually using an ESP32 to test the sketch. This time I switch to the cheaper ESP8266!

The Sketch

Here is the Arduino Sketch:

#define USE_HELIX 

#include "AudioTools.h"
#include "AudioCodecs/CodecAACHelix.h"

using namespace audio_tools;  

const char *urls[] = {
  "http://relay.publicdomainradio.org/jazz_swing.aac",
  "http://stream.srg-ssr.ch/m/couleur3/aacp_96",
  "http://live9.avf.ch:8000/ipmusicaacplus96"
};
const char *wifi = "wifi";
const char *password = "password";

URLStream urlStream(wifi, password);
AudioSourceURL source(urlStream, urls,"audio/aac",3, 0);
I2SStream i2s;
AACDecoderHelix decoder;
AudioPlayer player(source, i2s, decoder);
const int volumePin = A0; 

void setup() {
  Serial.begin(115200);
  AudioLogger::instance().begin(Serial, AudioLogger::Info);

  // setup output
  auto cfg = i2s.defaultConfig(TX_MODE);
  i2s.begin(cfg);

  // setup player
  player.begin();
}

void updateVolume() {
  // Reading potentiometer value 
  float vol = static_cast<float>(analogRead(volumePin)); 
  // min in 0 - max is 1.0
  player.setVolume(vol/1023.0); // or change for ESP32: 4095.0);
}

void loop() {
  updateVolume();
  player.copy();
}

In order to convert the MP3 code to support AAC, I just needed to replace the urls to provide AAC streams, replace the MP3DecoderHelix with AACDecoderHelix and change the mime to “audio/aac”.

In order to support the volume control, we read an analog Pin (e.g. GPIO15) and call the player.setVolume() method with a value that is in the rage between 0 and 1.0 and we just need to connect a Potentiometer to this pin.

Finally I removed the meta data logic, because this is not needed…

The External DAC

For my tests I am using the 24-bit PCM5102 PCM5102A Stereo DAC Digital-to-analog Converter PLL Voice Module pHAT

DAC

I am just using the default pins defined by the framework. However I could change them with the help of the config object. The mute pin can be defined in the constructor of the I2SStream – by not defining anything we use the default which is GPIO23

DAC ESP32 ESP8266
VDD 5V 5V
GND GND GND
SD OUT (GPIO22) GPIO3/RX0
L/R GND GND
WS WS (GPIO15) GPIO2/TX1
SCK BCK (GPIO14) GPIO15
FMT GND GND
XSMT +3V +3V
  • DEMP – De-emphasis control for 44.1kHz sampling rate(1): Off (Low) / On (High)
  • FLT – Filter select : Normal latency (Low) / Low latency (High)
  • SCK – System clock input (probably SCL on your board).
  • FMT – Audio format selection : I2S (Low) / Left justified (High)
  • XSMT – Soft mute control(1): Soft mute (Low) / soft un-mute (High)

Wiring the Potentiometer

DAC

Pot ESP32 ESP8266
POW 3V 3V
GND GND GND
VOUT A0/GPIO36 A0

Dependencies

The sketch is using the following dependencies:

Hardware Requirements

  • A Microcontroller that supports the Arduino WiFi library (e.g. ESP32, ESP8266…)
  • A potentiometer
  • An I2S Stereo DAC

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