1.Volume-Controlled-USB-DAC.ino

1.Volume-Controlled-USB-DAC

This is an example of the VolumeControl class of the Control Surface library. It acts as a USB Audio DAC (Digital-to-Analog Converter).

Boards: 🛈

Teensy 3.x

Connections

This specific example uses an I²S DAC, but you can use other interfaces of the Teensy Audio library as well. For testing, I'm using a PCM5102a.

• A0: wiper of a potentiometer to change the output volume
• 9: DAC BCK (I²S)
• 11: DAC SCK (I²S)
• 22: DAC DIN (I²S)
• 23: DAC LRCK (I²S)

Connect the left terminal of the potentiometer to ground, and the right one to V_CC.

Select a USB audio option from the Tools menu in the IDE.

Behavior

Upload the sketch, and select the Control Surface as the audio output of your computer. Connect the output of the DAC to a pair of headphones or powered speakers, and play some music.
You can now adjust the volume using the potentiometer.

Mapping

None.

Written by PieterP, 2019-08-09
https://github.com/tttapa/Control-Surface

 
#include <Control_Surface.h> // Include the Control Surface library
 
AudioInputUSB audioInputUSB; // The audio input from the USB connection
AudioMixer4 mixer_L;         // Two mixers for volume control
AudioMixer4 mixer_R;
AudioOutputI2S audioOutputI2S; // The output to the I²S DAC
 
AudioConnection patchCord1(audioInputUSB, 0, mixer_L, 0);  // Connect the input
AudioConnection patchCord3(audioInputUSB, 1, mixer_R, 0);  // to the mixer
AudioConnection patchCord5(mixer_L, 0, audioOutputI2S, 1); // Connect the mixer
AudioConnection patchCord6(mixer_R, 0, audioOutputI2S, 0); // to the output
 
// Instantiate a VolumeControl object with a potentiometer on pin A0 and a
// maximum gain of 1.0
VolumeControl<2> volume {{&mixer_L, &mixer_R}, A0, 1.0};
 
void setup() {
  volume.begin();
  // Add a dead zone if you can't get the volume all the way to zero
  // volume.map([](analog_t i) -> analog_t {
  //   const analog_t lower = 0 + 10;
  //   const analog_t upper = 1023 - 10;
  //   return map(constrain(i, lower, upper), lower, upper, 0, 1023);
  // });
  AudioMemory(6);
}
 
void loop() {
  volume.update();
}