70 lines
2.3 KiB
C++
70 lines
2.3 KiB
C++
/*
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AudioOutputULP
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Outputs to ESP32 DAC through the ULP, freeing I2S for other uses
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Copyright (C) 2020 Martin Laclaustra, based on bitluni's code
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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// Instructions:
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// AudioOutputULP out = new AudioOutputULP(); // stereo
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// Connect left channel on pin 25
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// Connect right channel on pin 26
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// OR
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// Connect mono channel on either of them (stereo samples are downmixed)
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// AudioOutputULP out = new AudioOutputULP(1); // mono, only DAC 1
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// OR
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// AudioOutputULP out = new AudioOutputULP(2); // mono, only DAC 2
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#ifndef _AUDIOOUTPUTULP_H
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#define _AUDIOOUTPUTULP_H
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#include "AudioOutput.h"
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#ifdef ESP32
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class AudioOutputULP : public AudioOutput
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{
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public:
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AudioOutputULP(int argActiveDACs=3) {if(argActiveDACs<1||argActiveDACs>2)argActiveDACs=3;activeDACs=argActiveDACs;stereoOutput=activeDACs==3;};
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~AudioOutputULP() {};
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virtual bool begin() override;
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virtual bool ConsumeSample(int16_t sample[2]) override;
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virtual bool stop() override;
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enum : int { DAC1 = 1, DAC2 = 2 };
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private:
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int lastFilledWord = 0;
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uint8_t bufferedOddSample = 128;
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bool waitingOddSample = true; // must be set to false for mono output
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int activeDACs = 3; // 1:DAC1; 2:DAC2; 3:both;
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bool stereoOutput = true;
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const int opcodeCount = 20;
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const uint32_t dacTableStart1 = 2048 - 512;
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const uint32_t dacTableStart2 = dacTableStart1 - 512;
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uint32_t totalSampleWords = 2048 - 512 - 512 - (opcodeCount + 1); // add 512 for mono
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const int totalSamples = totalSampleWords * 2;
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const uint32_t indexAddress = opcodeCount;
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const uint32_t bufferStart = indexAddress + 1;
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};
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#else
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#error Only the ESP32 supports ULP audio output
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#endif
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#endif
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