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58 lines
2.5 KiB
58 lines
2.5 KiB
<script type="text/x-red" data-help-name="AudioInputAnalogStereo">
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<h3>Summary</h3>
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<div class=tooltipinfo>
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<p>Receive stereo audio using the built-in analog to digital converters.</p>
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</div>
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<h3>Audio Connections</h3>
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<table class=doc align=center cellpadding=3>
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<tr class=top><th>Port</th><th>Purpose</th></tr>
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<tr class=odd><td align=center>Out 0</td><td>Audio Channel (Left)</td></tr>
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<tr class=odd><td align=center>Out 1</td><td>Audio Channel (Right)</td></tr>
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</table>
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<h3>Functions</h3>
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<p>This object has no functions to call from the Arduino sketch. It
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simply streams data from both ADCs to its output ports.</p>
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<h3>Hardware</h3>
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<p>By default, pins A2 & A3 are used for audio input. This circuitry is recommended.</p>
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<p align=center><img src="img/adccircuit2.png"></p>
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<p>Signal range is 0 to 1.2V</p>
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<h3>Examples</h3>
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<!--
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<p class=exam>File > Examples > Audio > HardwareTesting > PassThroughMono
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</p>
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<p class=exam>File > Examples > Audio > Analysis > PeakMeterMono
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</p>
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<p class=exam>File > Examples > Audio > Analysis > DialTone_7segment
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</p>
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<p class=exam>File > Examples > OctoWS2811 > SpectrumAnalyzer
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</p>
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-->
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<h3>Notes</h3>
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<p><b>analogRead() must not be used</b>, because AudioInputAnalogStereo is regularly
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accessing the ADC hardware. If both access the hardware at the same
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moment, analogRead() can end up waiting forever, which effectively
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crashes your program.
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</p>
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<p>A different pin may be used, but adding it as an parameter
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to the AudioInputAnalog object definition.
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</p>
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<p>For example:
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</p>
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<p class=desc><span class=keyword>AudioInputAnalogStereo</span> adc1(<span class=literal>A3</span>, <span class=literal>A2</span>);
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</p>
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<p>TODO: add info here about which pins work for input 0 and 1.
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</p>
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<p>Noise due to high source impedance, which allows rapidly switching digital signals
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to capacitively couple... avoiding higher analog impedance is the solution.</p>
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<p>Power Supply rejection issue with simple DC bias (bigger capacitor may be needed if 3.3V has low frequency noise)</p>
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<p>Algorithm for automatic DC bias tracking</p>
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<p>TODO: actual noise measurements with different input circuitry
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(it's not as quiet as the audio shield)</p>
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</script>
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<script type="text/x-red" data-template-name="AudioInputAnalogStereo">
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<div class="form-row">
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<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
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<input type="text" id="node-input-name" placeholder="Name">
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</div>
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</script>
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