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350 lines
15 KiB
350 lines
15 KiB
<script type="text/x-red" data-help-name="AudioControlSGTL5000">
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<h3>Summary</h3>
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<div class=tooltipinfo>
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<p>Control the SGTL5000 chip on the
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<a href="http://www.pjrc.com/store/teensy3_audio.html" target="_blank">audio shield</a>.
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SGTL5000 is always used in slave mode, where Teensy controls
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all I2S timing.
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</p>
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<p align=center><img src="img/sgtl5000closeup.jpg"></p>
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</div>
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<h3>Audio Connections</h3>
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<p>This object has no audio inputs or outputs. Separate i2s objects
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are used to send and receive audio data. I2S master mode objects
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must be used, because this object configures the SGTL5000 in slave
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mode, where it depends on Teensy to provide all I2S clocks.
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This object controls
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how the SGTL5000 will use those I2S audio streams.</p>
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<h3>Functions</h3>
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<p>These are the most commonly used SGTL5000 functions.</p>
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<p class=func><span class=keyword>enable</span>();</p>
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<p class=desc>Start the SGTL5000. This function should be called first.
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</p>
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<p class=func><span class=keyword>volume</span>(level);</p>
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<p class=desc>Set the headphone volume level. Range is 0 to 1.0, but
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0.8 corresponds to the maximum undistorted output for a full scale
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signal. Usually 0.5 is a comfortable listening level. The line
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level outputs are <em>not</em> changed by this function.
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</p>
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<p class=func><span class=keyword>inputSelect</span>(input);</p>
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<p class=desc>Select which input to use: AUDIO_INPUT_LINEIN or AUDIO_INPUT_MIC.
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</p>
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<p class=func><span class=keyword>micGain</span>(dB);</p>
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<p class=desc>When using the microphone input, set the amplifier gain.
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The input number is in decibels, from 0 to 63.
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</p>
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<h3>Signal Levels</h3>
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<p>The default signal levels should be used for most applications,
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but these functions allow you to customize the analog signals.</p>
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<p class=func><span class=keyword>muteHeadphone</span>();</p>
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<p class=desc>Silence the headphone output.
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</p>
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<p class=func><span class=keyword>unmuteHeadphone</span>();</p>
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<p class=desc>Turn the headphone output on.
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</p>
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<p class=func><span class=keyword>muteLineout</span>();</p>
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<p class=desc>Silence the line level outputs.
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</p>
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<p class=func><span class=keyword>unmuteLineout</span>();</p>
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<p class=desc>Turn the line level outputs on.
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</p>
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<p class=func><span class=keyword>lineInLevel</span>(both);</p>
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<p class=desc style="padding-bottom:0.2em;">Adjust the sensitivity of the line-level inputs.
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Fifteen settings are possible:
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</p>
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<pre class="desc">
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0: 3.12 Volts p-p
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1: 2.63 Volts p-p
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2: 2.22 Volts p-p
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3: 1.87 Volts p-p
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4: 1.58 Volts p-p
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5: 1.33 Volts p-p (default)
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6: 1.11 Volts p-p
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7: 0.94 Volts p-p
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8: 0.79 Volts p-p
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9: 0.67 Volts p-p
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10: 0.56 Volts p-p
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11: 0.48 Volts p-p
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12: 0.40 Volts p-p
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13: 0.34 Volts p-p
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14: 0.29 Volts p-p
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15: 0.24 Volts p-p
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</pre>
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<p class=func><span class=keyword>lineInLevel</span>(left, right);</p>
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<p class=desc>Adjust the sensitivity of the line-level inputs, with different
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settings for left and right. The same 15 settings are available.
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</p>
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<p class=func><span class=keyword>lineOutLevel</span>(both);</p>
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<p class=desc style="padding-bottom:0.2em;">Adjust the line level output
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voltage range. The following settings are possible:
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</p>
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<pre class="desc">
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13: 3.16 Volts p-p
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14: 2.98 Volts p-p
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15: 2.83 Volts p-p
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16: 2.67 Volts p-p
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17: 2.53 Volts p-p
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18: 2.39 Volts p-p
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19: 2.26 Volts p-p
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20: 2.14 Volts p-p
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21: 2.02 Volts p-p
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22: 1.91 Volts p-p
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23: 1.80 Volts p-p
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24: 1.71 Volts p-p
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25: 1.62 Volts p-p
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26: 1.53 Volts p-p
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27: 1.44 Volts p-p
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28: 1.37 Volts p-p
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29: 1.29 Volts p-p (default)
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30: 1.22 Volts p-p
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31: 1.16 Volts p-p
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</pre>
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<p class=func><span class=keyword>lineOutLevel</span>(left, right);</p>
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<p class=desc>Adjust the line level outout voltage range, with separate
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settings for left and right. The same settings (13 to 31) are available.
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</p>
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<h3>Signal Conditioning</h3>
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<p>Usually these digital signal conditioning features should be left at their
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default settings.
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</p>
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<p class=func><span class=keyword>adcHighPassFilterFreeze</span>();</p>
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<p class=desc>By default, the analog input (either line-level inputs or mic)
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is high-pass filtered, to remove any DC component. This function
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freezes the filter, so the current DC component is still substracted, but
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the filter stops tracking any DC or low frequency changes.
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</p>
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<p class=func><span class=keyword>adcHighPassFilterDisable</span>();</p>
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<p class=desc>Completely disable the analog input filter. DC and sub-audible
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low frequencies are allowed to enter the digital signal.
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</p>
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<p class=func><span class=keyword>adcHighPassFilterEnable</span>();</p>
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<p class=desc>Turn the DC-blocking filter back on, if disabled, or
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allows it to resume tracking DC and low frequency changes, if
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previously frozen. This is the default setting.
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</p>
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<p class=func><span class=keyword>dacVolume</span>(both);</p>
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<p class=desc>Normally output volume should be used with volume(), which
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changes the analog gain in the headphone amplifier. This function
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on the other hand controls digital attenuation before conversion to analog, which
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reduces resolution, but allows another fine control of output
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signal level. The ranges is 0 to 1.0, with the default (no digital attenuation)
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at 1.0.
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</p>
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<p class=desc>dacVolume uses zero-crossing detect to avoid clicks, and graceful
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ramping is handled by the chip so that a new volume may be set directly in
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a single call.
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</p>
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<p class=func><span class=keyword>dacVolume</span>(left, right);</p>
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<p class=desc>Adjust the digital output volume separately on left and
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right channels.
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</p>
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<p class=func><span class=keyword>dacVolumeRamp</span>();</p>
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<p class=desc>Enable graceful volume ramping. The dacVolume adjusts gradually using
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an exponential curve. Pops or loud clicks are avoided when making large
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changes in volume level.
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</p>
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<p class=func><span class=keyword>dacVolumeRampLinear</span>();</p>
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<p class=desc>Enable faster volume ramping. A slight click may be heard during a
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large volume change.
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</p>
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<p class=func><span class=keyword>dacVolumeRampDisable</span>();</p>
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<p class=desc>Do not use any gradual ramping. The zero cross feature still helps
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for small changes, but large volume changes may produce a pop or click.
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</p>
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<h3>Audio Processor</h3>
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<p>The optional digital audio processor is capable of implementing
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one or more of: automatic volume control, surround sound control,
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bass enhancement, and tonal adjustments (either a
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simple tone control, or a parametric equalizer, or a graphic equalizer),
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in that order.
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</p>
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<p>These signal processing features are implemented in the SGTL5000 chip,
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so they do not consume CPU time on Teensy. However, the order of
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these processes is fixed in the hardware.
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</p>
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<p>It is good practice to mute the outputs before enabling or disabling
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the Audio Processor, to avoid clicks or thumps.
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</p>
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<p class=func><span class=keyword>audioPreProcessorEnable</span>();</p>
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<p class=desc>Enable the audio processor to pre-process the input
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(from either line-level inputs or microphone) before it's sent
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to Teensy by I2S.
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</p>
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<p class=func><span class=keyword>audioPostProcessorEnable</span>();</p>
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<p class=desc>Enable the audio processor to post-process Teensy's
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I2S output before it's turned into analog signals for the
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headphones and/or line level outputs.
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</p>
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<p class=func><span class=keyword>audioProcessorDisable</span>();</p>
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<p class=desc>Disable the audio processor.
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</p>
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<p class=func><span class=keyword>autoVolumeControl</span>(maxGain, response, hardLimit, threshold, attack, decay);</p>
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<p class=desc>Configures the auto volume control, which is implemented as a compressor/expander
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or hard limiter. <em>maxGain</em> is the maximum gain that can be applied for expanding, and
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can take one of three values: 0 (0dB), 1 (6.0dB) and 2 (12dB). Values greater than 2 are treated
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as 2. <em>response</em> controls the integration time for the compressor and can take
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four values: 0 (0ms), 1 (25ms), 2 (50ms) or 3 (100ms). Larger values average the volume
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over a longer time, allowing short-term peaks through.
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</p>
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<p class=desc>If <em>hardLimit</em> is 0, a 'soft
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knee' compressor is used to progressively compress louder values which are near to or above the
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threashold (the louder they are, the greater the compression). If it is 1, a hard compressor
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is used (all values above the threashold are the same loudness). The <em>threashold</em> is specified
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as a float in the range 0dBFS to -96dBFS, where -18dBFS is a typical value.
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<em>attack</em> is a float controlling the rate of decrease in gain when the signal is over
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threashold, in dB/s. <em>decay</em> controls how fast gain is restored once the level
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drops below threashold, again in dB/s. It is typically set to a longer value than attack.
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</p>
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<p class=func><span class=keyword>autoVolumeEnable</span>();</p>
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<p class=desc>Enables auto volume control, using the previously specified settings.
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</p>
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<p class=func><span class=keyword>autoVolumeDisable</span>();</p>
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<p class=desc>Disables auto volume control.
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</p>
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<p class=func><span class=keyword>surroundSoundEnable</span>();</p>
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<p class=desc>Enable virtual surround processing, to give a broader and
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deeper stereo image (even with mono input).
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</p>
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<p class=func><span class=keyword>surroundSoundDisable</span>();</p>
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<p class=desc>Disable virtual surround processing. Before disabling, ramp up
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the width to maximum to avoid pops.
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</p>
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<p class=func><span class=keyword>surroundSound</span>(width);</p>
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<p class=desc>Configures virtual surround width from 0 (mono) to 7 (widest).
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</p>
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<p class=func><span class=keyword>surroundSound</span>(width, select);</p>
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<p class=desc>Configures virtual surround width from 0 (mono) to 7 (widest).
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<em>select</em> may be set to 1 (disable), 2 (mono input) or 3 (stereo input).
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</p>
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<p class=func><span class=keyword>enhanceBassEnable</span>();</p>
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<p class=desc>Enable bass enhancement. A mono, low-pass filtered copy of
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the original stereo signal has bass levels boosted and is then mixed back into
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the stereo signal, which is then optionally high pass filtered (to remove
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inaudible subsonic frequencies).
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</p>
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<p class=func><span class=keyword>enhanceBassDisable</span>();</p>
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<p class=desc>Disable bass enhancement. Before disabling, ramp down the bass
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enhancement level to zero.
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</p>
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<p class=func><span class=keyword>enhanceBass</span>(lr_lev, bass_lev);</p>
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<p class=desc>Configures the bass enhancement by setting the levels of the
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original stereo signal and the bass-enhanced mono level which will be mixed together.
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There is no high-pass filter.
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</p>
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<p class=desc>When changing bass level, call this function repeatedly to ramp up or down the bass in
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steps of 0.5dB, to avoid pops.
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</p>
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<p class=func><span class=keyword>enhanceBass</span>(lr_lev, bass_lev, hpf_bypass, cutoff);</p>
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<p class=desc>Configures the bass enhancement by setting the levels of the
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original stereo signal and the bass-enhanced mono level which will be mixed together.
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The high-pass filter may be enabled (0) or bypassed (1). The cutoff frequency is specified
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as follows:
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</p>
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<pre class="desc">
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value frequency
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0 80Hz
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1 100Hz
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2 125Hz
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3 150Hz
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4 175Hz
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5 200Hz
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6 225Hz
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</pre>
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<p class=desc>When changing bass level, call this function repeatedly to ramp up or down the bass in
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steps of 0.5dB, to avoid pops.
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</p>
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<p class=func><span class=keyword>eqSelect</span>(n);</p>
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<p class=desc>Selects the type of frequency control, where <em>n</em> is
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one of</p>
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<p class=desc><b>FLAT_FREQUENCY (0)</b><br>
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Equalizers and tone controls disabled, flat frequency response.</p>
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<p class=desc><b>PARAMETRIC_EQUALIZER (1)</b><br>
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Enables the 7-band parametric equalizer, thus disabling the
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tone controls and graphic equalizer.</p>
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<p class=desc><b>TONE_CONTROLS (2)</b><br>
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Enables bass and treble tone controls, disabling the parametric
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equalization and graphic equalizer.</p>
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<p class=desc><b>GRAPHIC_EQUALIZER (3)</b><br>
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Enables the five-band graphic equalizer, disabling the parametric
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equalization and tone controls.</p>
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<p class=func><span class=keyword>eqBands</span>(bass, treble);</p>
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<p class=desc>Configures bass and treble tone controls, which are
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implemented as one second order low pass filter (bass) in parallel with
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one second order high pass filter (treble).
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</p>
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<p class=desc>When changing bass or treble level, call this function repeatedly to ramp
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up or down the level in steps of 0.04 (=0.5dB) or so, to avoid pops.
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</p>
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<p class=func><span class=keyword>eqBands</span>(bass, mid_bass, midrange, mid_treble, treble);</p>
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<p class=desc>Configures the graphic equalizer. It is implemented by five parallel,
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second order biquad filters with fixed frequencies of 115Hz, 330Hz, 990Hz, 3kHz,
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and 9.9kHz. Each band has a range of adjustment from 1.00 (+12dB) to -1.00 (-11.75dB).
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</p>
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<p class=func><span class=keyword>eqBand</span>(bandNum, n);</p>
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<p class=desc>Configures the gain or cut on one band in the graphic equalizer.
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<em>bandnum</em> can range from 1 to 5; <em>n</em> is a float in the range 1.00 to -1.00.
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</p>
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<p class=desc>When changing a band, call this function repeatedly to ramp up the gain in steps of 0.5dB,
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to avoid pops.
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</p>
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<p class=func><span class=keyword>eqFilter</span>(filterNum, filterParameters);</p>
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<p class=desc>Configurs the parametric equalizer. The number of filters (1 to 7)
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is specified along with a pointer to an array of filter coefficients.
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The parametric equalizer is implemented using 7 cascaded, second order bi-quad
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filters whose frequencies, gain, and Q may be freely configured, but each filter
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can only be specified as a set of filter coefficients.
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</p>
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<p class=func><span class=keyword>eqFilterCount</span>(n);</p>
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<p class=desc>Enables zero or more of the already enabled parametric filters.
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</p>
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<h3>Examples</h3>
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<p>Nearly all of the library's examples use this object. These
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examples demonstrate its special features.
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</p>
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<p class=exam>File > Examples > Audio > HardwareTesting > PassThroughStereo
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</p>
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<p class=exam>File > Examples > Audio > HardwareTesting > SGTL5000 > dap_bass_enhance
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</p>
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<p class=exam>File > Examples > Audio > HardwareTesting > SGTL5000 > dap_avc_agc
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</p>
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<p class=exam>File > Examples > Audio > HardwareTesting > SGTL5000 > balanceDAC
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</p>
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<p class=exam>File > Examples > Audio > HardwareTesting > SGTL5000 > balanceHP
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</p>
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<p class=exam>File > Examples > Audio > HardwareTesting > SGTL5000 > CalcBiquadToneControlDAP
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</p>
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<p class=exam>File > Examples > Audio > HardwareTesting > SGTL5000 > VolumeRamp
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</p>
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<h3>Notes</h3>
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<p>TODO: add example with rock/classical/speech presets, where rock uses bass boost
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and surround enhancement while speech uses bandpass filtering and auto volume control
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compression.
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</p>
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<p>TODO: add example with two analogRead pots for bass and treble to demonstrate ramping.
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</p>
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</script>
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<script type="text/x-red" data-template-name="AudioControlSGTL5000">
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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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