59 lines
2.1 KiB
ReStructuredText
59 lines
2.1 KiB
ReStructuredText
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The AMP audio skin
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==================
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Soldering and using the AMP audio skin.
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[<img src="/static/doc/skin-amp-1.jpg" alt="AMP skin" style="width:250px; border:1px solid black; display:inline-block;"/>](/static/doc/skin-amp-1.jpg)
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[<img src="/static/doc/skin-amp-3.jpg" alt="AMP skin" style="width:250px; border:1px solid black; display:inline-block;"/>](/static/doc/skin-amp-3.jpg)
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The following video shows how to solder the headers, microphone and speaker onto the AMP skin.
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<iframe style="margin-left:3em;" width="560" height="315" src="//www.youtube.com/embed/fjB1DuZRveo?rel=0" frameborder="0" allowfullscreen></iframe>
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Example code
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------------
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The AMP skin has a speaker which is connected to DAC(1) via a small
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power amplifier. The volume of the amplifier is controlled by a digital
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potentiometer, which is an I2C device with address 46 on the IC2(1) bus.
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To set the volume, define the following function::
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def volume(val):
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pyb.I2C(1, pyb.I2C.MASTER).mem_write(val, 46, 0)
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Then you can do::
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>>> volume(0) # minimum volume
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>>> volume(127) # maximum volume
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To play a sound, use the ``write_timed`` method of the ``DAC`` object.
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For example::
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import math
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from pyb import DAC
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# create a buffer containing a sine-wave
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buf = bytearray(100)
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for i in range(len(buf)):
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buf[i] = 128 + int(127 * math.sin(2 * math.pi * i / len(buf)))
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# output the sine-wave at 400Hz
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dac = DAC(1)
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dac.write_timed(buf, 400 * len(buf), mode=DAC.CIRCULAR)
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You can also play WAV files using the Python ``wave`` module. You can get
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the wave module [here](/static/doc/examples/wave.py) and you will also need
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the chunk module available [here](/static/doc/examples/chunk.py). Put these
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on your pyboard (either on the flash or the SD card in the top-level
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directory). You will need an 8-bit WAV file to play, such as
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[this one](/static/doc/examples/test.wav). Then you can do::
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>>> import wave
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>>> from pyb import DAC
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>>> dac = DAC(1)
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>>> f = wave.open('test.wav')
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>>> dac.write_timed(f.readframes(f.getnframes()), f.getframerate())
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This should play the WAV file.
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