2014-09-25 16:21:59 +00:00
|
|
|
The AMP audio skin
|
|
|
|
==================
|
|
|
|
|
|
|
|
Soldering and using the AMP audio skin.
|
|
|
|
|
2014-11-03 22:14:23 +00:00
|
|
|
.. image:: img/skin_amp_1.jpg
|
2014-09-25 18:42:27 +00:00
|
|
|
:alt: AMP skin
|
|
|
|
:width: 250px
|
|
|
|
|
2014-11-03 22:14:23 +00:00
|
|
|
.. image:: img/skin_amp_2.jpg
|
2014-09-25 18:42:27 +00:00
|
|
|
:alt: AMP skin
|
|
|
|
:width: 250px
|
2014-09-25 16:21:59 +00:00
|
|
|
|
|
|
|
The following video shows how to solder the headers, microphone and speaker onto the AMP skin.
|
|
|
|
|
2014-09-25 18:42:27 +00:00
|
|
|
.. raw:: html
|
|
|
|
|
|
|
|
<iframe style="margin-left:3em;" width="560" height="315" src="http://www.youtube.com/embed/fjB1DuZRveo?rel=0" frameborder="0" allowfullscreen></iframe>
|
2014-09-25 16:21:59 +00:00
|
|
|
|
2014-12-02 12:32:39 +00:00
|
|
|
For circuit schematics and datasheets for the components on the skin see :ref:`hardware_index`.
|
|
|
|
|
2014-09-25 16:21:59 +00:00
|
|
|
Example code
|
|
|
|
------------
|
|
|
|
|
2014-09-25 18:42:27 +00:00
|
|
|
The AMP skin has a speaker which is connected to ``DAC(1)`` via a small
|
2014-09-25 16:21:59 +00:00
|
|
|
power amplifier. The volume of the amplifier is controlled by a digital
|
2014-09-25 18:42:27 +00:00
|
|
|
potentiometer, which is an I2C device with address 46 on the ``IC2(1)`` bus.
|
2014-09-25 16:21:59 +00:00
|
|
|
|
|
|
|
To set the volume, define the following function::
|
|
|
|
|
2014-10-31 01:37:19 +00:00
|
|
|
import pyb
|
2014-09-25 16:21:59 +00:00
|
|
|
def volume(val):
|
|
|
|
pyb.I2C(1, pyb.I2C.MASTER).mem_write(val, 46, 0)
|
|
|
|
|
|
|
|
Then you can do::
|
|
|
|
|
|
|
|
>>> volume(0) # minimum volume
|
|
|
|
>>> volume(127) # maximum volume
|
|
|
|
|
|
|
|
To play a sound, use the ``write_timed`` method of the ``DAC`` object.
|
|
|
|
For example::
|
|
|
|
|
|
|
|
import math
|
|
|
|
from pyb import DAC
|
|
|
|
|
|
|
|
# create a buffer containing a sine-wave
|
|
|
|
buf = bytearray(100)
|
|
|
|
for i in range(len(buf)):
|
|
|
|
buf[i] = 128 + int(127 * math.sin(2 * math.pi * i / len(buf)))
|
|
|
|
|
|
|
|
# output the sine-wave at 400Hz
|
|
|
|
dac = DAC(1)
|
|
|
|
dac.write_timed(buf, 400 * len(buf), mode=DAC.CIRCULAR)
|
|
|
|
|
|
|
|
You can also play WAV files using the Python ``wave`` module. You can get
|
2014-11-03 22:14:23 +00:00
|
|
|
the wave module `here <http://micropython.org/resources/examples/wave.py>`_ and you will also need
|
|
|
|
the chunk module available `here <http://micropython.org/resources/examples/chunk.py>`_. Put these
|
2014-09-25 16:21:59 +00:00
|
|
|
on your pyboard (either on the flash or the SD card in the top-level
|
|
|
|
directory). You will need an 8-bit WAV file to play, such as
|
2014-11-03 22:14:23 +00:00
|
|
|
`this one <http://micropython.org/resources/examples/test.wav>`_. Then you can do::
|
2014-09-25 16:21:59 +00:00
|
|
|
|
|
|
|
>>> import wave
|
|
|
|
>>> from pyb import DAC
|
|
|
|
>>> dac = DAC(1)
|
|
|
|
>>> f = wave.open('test.wav')
|
|
|
|
>>> dac.write_timed(f.readframes(f.getnframes()), f.getframerate())
|
|
|
|
|
|
|
|
This should play the WAV file.
|