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106 lines
5.5 KiB
106 lines
5.5 KiB
/*
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BasicGain
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Created: Chip Audette, Nov 2016
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Purpose: Process audio by applying gain.
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Demonstrates audio processing using floating point data type.
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Uses Teensy Audio Adapter.
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Assumes microphones (or whatever) are attached to the LINE IN (stereo)
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MIT License. use at your own risk.
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*/
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//These are the includes from the Teensy Audio Library
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#include <Audio.h> //Teensy Audio Librarya
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#include <Wire.h>
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#include <SPI.h>
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#include <SD.h>
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#include <SerialFlash.h>
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#include <OpenAudio_ArduinoLibrary.h> //for AudioConvert_I16toF32, AudioConvert_F32toI16, and AudioEffectGain_F32
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//create audio library objects for handling the audio
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AudioControlSGTL5000 sgtl5000_1; //controller for the Teensy Audio Board
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AudioInputI2S i2s_in; //Digital audio *from* the Teensy Audio Board ADC. Sends Int16. Stereo.
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AudioOutputI2S i2s_out; //Digital audio *to* the Teensy Audio Board DAC. Expects Int16. Stereo
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AudioConvert_I16toF32 int2Float1, int2Float2; //Converts Int16 to Float. See class in AudioStream_F32.h
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AudioConvert_F32toI16 float2Int1, float2Int2; //Converts Float to Int16. See class in AudioStream_F32.h
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AudioEffectGain_F32 gain1, gain2; //Applies digital gain to audio data. Expected Float data.
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//Make all of the audio connections
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AudioConnection patchCord1(i2s_in, 0, int2Float1, 0); //connect the Left input to the Left Int->Float converter
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AudioConnection patchCord2(i2s_in, 1, int2Float2, 0); //connect the Right input to the Right Int->Float converter
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AudioConnection_F32 patchCord10(int2Float1, 0, gain1, 0); //Left. makes Float connections between objects
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AudioConnection_F32 patchCord11(int2Float2, 0, gain2, 0); //Right. makes Float connections between objects
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AudioConnection_F32 patchCord12(gain1, 0, float2Int1, 0); //Left. makes Float connections between objects
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AudioConnection_F32 patchCord13(gain2, 0, float2Int2, 0); //Right. makes Float connections between objects
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AudioConnection patchCord20(float2Int1, 0, i2s_out, 0); //connect the Left float processor to the Left output
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AudioConnection patchCord21(float2Int2, 0, i2s_out, 1); //connect the Right float processor to the Right output
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// which input on the audio shield will be used?
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const int myInput = AUDIO_INPUT_LINEIN;
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//const int myInput = AUDIO_INPUT_MIC;
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//I have a potentiometer on the Teensy Audio Board
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#define POT_PIN A1 //potentiometer is tied to this pin
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// define the setup() function, the function that is called once when the device is booting
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void setup() {
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Serial.begin(115200); //open the USB serial link to enable debugging messages
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delay(500); //give the computer's USB serial system a moment to catch up.
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Serial.println("Teensy Hearing Aid: BasicGain_Float..."); //identify myself over the USB serial
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// Audio connections require memory, and the record queue
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// uses this memory to buffer incoming audio.
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AudioMemory(10); //allocate Int16 audio data blocks
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AudioMemory_F32(10); //allocate Float32 audio data blocks
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// Enable the audio shield, select input, and enable output
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sgtl5000_1.enable(); //start the audio board
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sgtl5000_1.inputSelect(myInput); //choose line-in or mic-in
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sgtl5000_1.volume(0.8); //volume can be 0.0 to 1.0. 0.5 seems to be the usual default.
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sgtl5000_1.lineInLevel(10,10); //level can be 0 to 15. 5 is the Teensy Audio Library's default
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sgtl5000_1.adcHighPassFilterDisable(); //reduces noise. https://forum.pjrc.com/threads/27215-24-bit-audio-boards?p=78831&viewfull=1#post78831
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// setup any other other features
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pinMode(POT_PIN, INPUT); //set the potentiometer's input pin as an INPUT
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} //end setup()
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// define the loop() function, the function that is repeated over and over for the life of the device
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unsigned long updatePeriod_millis = 100; //how many milliseconds between updating gain reading?
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unsigned long lastUpdate_millis = 0;
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unsigned long curTime_millis = 0;
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int prev_gain_dB = 0;
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void loop() {
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//choose to sleep ("wait for interrupt") instead of spinning our wheels doing nothing but consuming power
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asm(" WFI"); //ARM-specific. Will wake on next interrupt. The audio library issues tons of interrupts, so we wake up often.
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//has enough time passed to try updating the GUI?
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curTime_millis = millis(); //what time is it right now
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if (curTime_millis < lastUpdate_millis) lastUpdate_millis = 0; //handle wrap-around of the clock
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if ((curTime_millis - lastUpdate_millis) > updatePeriod_millis) { //is it time to update the user interface?
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//read potentiometer
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float val = float(analogRead(POT_PIN)) / 1024.0; //0.0 to 1.0
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val = 0.1*(float)((int)(10.0*val + 0.5)); //quantize so that it doesn't chatter
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//compute desired digital gain
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const float min_gain_dB = -20.0, max_gain_dB = 40.0; //set desired gain range
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float gain_dB = min_gain_dB + (max_gain_dB - min_gain_dB)*val; //computed desired gain value in dB
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//if the gain is different than before, set the new gain value
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if (abs(gain_dB - prev_gain_dB) > 1.0) { //is it different than before
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gain1.setGain_dB(gain_dB); //set the gain of the Left-channel gain processor
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gain2.setGain_dB(gain_dB); //set the gain of the Right-channel gain processor
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Serial.print("Digital Gain dB = "); Serial.println(gain_dB); //print text to Serial port for debugging
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prev_gain_dB = gain_dB; //we will use this value the next time around
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}
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lastUpdate_millis = curTime_millis; //we will use this value the next time around.
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} // end if
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} //end loop();
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