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86 lines
2.7 KiB
86 lines
2.7 KiB
The LCD and touch-sensor skin
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=============================
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Soldering and using the LCD and touch-sensor skin.
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.. image:: img/skin_lcd_1.jpg
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:alt: pyboard with LCD skin
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:width: 250px
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.. image:: img/skin_lcd_2.jpg
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:alt: pyboard with LCD skin
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:width: 250px
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The following video shows how to solder the headers onto the LCD skin.
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At the end of the video, it shows you how to correctly connect the LCD skin to the pyboard.
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.. raw:: html
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<iframe style="margin-left:3em;" width="560" height="315" src="http://www.youtube.com/embed/PowCzdLYbFM?rel=0" frameborder="0" allowfullscreen></iframe>
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For circuit schematics and datasheets for the components on the skin see :ref:`hardware_index`.
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Using the LCD
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-------------
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To get started using the LCD, try the following at the MicroPython prompt.
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Make sure the LCD skin is attached to the pyboard as pictured at the top of this page. ::
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>>> import pyb
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>>> lcd = pyb.LCD('X')
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>>> lcd.light(True)
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>>> lcd.write('Hello uPy!\n')
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You can make a simple animation using the code::
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import pyb
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lcd = pyb.LCD('X')
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lcd.light(True)
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for x in range(-80, 128):
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lcd.fill(0)
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lcd.text('Hello uPy!', x, 10, 1)
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lcd.show()
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pyb.delay(25)
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Using the touch sensor
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----------------------
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To read the touch-sensor data you need to use the I2C bus. The
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MPR121 capacitive touch sensor has address 90.
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To get started, try::
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>>> import pyb
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>>> i2c = pyb.I2C(1, pyb.I2C.CONTROLLER)
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>>> i2c.mem_write(4, 90, 0x5e)
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>>> touch = i2c.mem_read(1, 90, 0)[0]
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The first line above makes an I2C object, and the second line
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enables the 4 touch sensors. The third line reads the touch
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status and the ``touch`` variable holds the state of the 4 touch
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buttons (A, B, X, Y).
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There is a simple driver `here <http://micropython.org/resources/examples/mpr121.py>`__
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which allows you to set the threshold and debounce parameters, and
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easily read the touch status and electrode voltage levels. Copy
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this script to your pyboard (either flash or SD card, in the top
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directory or ``lib/`` directory) and then try::
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>>> import pyb
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>>> import mpr121
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>>> m = mpr121.MPR121(pyb.I2C(1, pyb.I2C.CONTROLLER))
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>>> for i in range(100):
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... print(m.touch_status())
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... pyb.delay(100)
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...
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This will continuously print out the touch status of all electrodes.
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Try touching each one in turn.
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Note that if you put the LCD skin in the Y-position, then you need to
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initialise the I2C bus using::
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>>> m = mpr121.MPR121(pyb.I2C(2, pyb.I2C.CONTROLLER))
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There is also a demo which uses the LCD and the touch sensors together,
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and can be found `here <http://micropython.org/resources/examples/lcddemo.py>`__.
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