132 lines
4.9 KiB
ReStructuredText
132 lines
4.9 KiB
ReStructuredText
Making the pyboard act as a USB mouse
|
|
=====================================
|
|
|
|
The pyboard is a USB device, and can configured to act as a mouse instead
|
|
of the default USB flash drive.
|
|
|
|
To do this we must first edit the ``boot.py`` file to change the USB
|
|
configuration. If you have not yet touched your ``boot.py`` file then it
|
|
will look something like this::
|
|
|
|
# boot.py -- run on boot-up
|
|
# can run arbitrary Python, but best to keep it minimal
|
|
|
|
import pyb
|
|
#pyb.main('main.py') # main script to run after this one
|
|
#pyb.usb_mode('VCP+MSC') # act as a serial and a storage device
|
|
#pyb.usb_mode('VCP+HID') # act as a serial device and a mouse
|
|
|
|
To enable the mouse mode, uncomment the last line of the file, to
|
|
make it look like::
|
|
|
|
pyb.usb_mode('VCP+HID') # act as a serial device and a mouse
|
|
|
|
If you already changed your ``boot.py`` file, then the minimum code it
|
|
needs to work is::
|
|
|
|
import pyb
|
|
pyb.usb_mode('VCP+HID')
|
|
|
|
This tells the pyboard to configure itself as a VCP (Virtual COM Port,
|
|
ie serial port) and HID (human interface device, in our case a mouse)
|
|
USB device when it boots up.
|
|
|
|
Eject/unmount the pyboard drive and reset it using the RST switch.
|
|
Your PC should now detect the pyboard as a mouse!
|
|
|
|
Sending mouse events by hand
|
|
----------------------------
|
|
|
|
To get the py-mouse to do anything we need to send mouse events to the PC.
|
|
We will first do this manually using the REPL prompt. Connect to your
|
|
pyboard using your serial program and type the following::
|
|
|
|
>>> hid = pyb.USB_HID()
|
|
>>> hid.send((0, 10, 0, 0))
|
|
|
|
Your mouse should move 10 pixels to the right! In the command above you
|
|
are sending 4 pieces of information: button status, x, y and scroll. The
|
|
number 10 is telling the PC that the mouse moved 10 pixels in the x direction.
|
|
|
|
Let's make the mouse oscillate left and right::
|
|
|
|
>>> import math
|
|
>>> def osc(n, d):
|
|
... for i in range(n):
|
|
... hid.send((0, int(20 * math.sin(i / 10)), 0, 0))
|
|
... pyb.delay(d)
|
|
...
|
|
>>> osc(100, 50)
|
|
|
|
The first argument to the function ``osc`` is the number of mouse events to send,
|
|
and the second argument is the delay (in milliseconds) between events. Try
|
|
playing around with different numbers.
|
|
|
|
**Exercise: make the mouse go around in a circle.**
|
|
|
|
Making a mouse with the accelerometer
|
|
-------------------------------------
|
|
|
|
Now lets make the mouse move based on the angle of the pyboard, using the
|
|
accelerometer. The following code can be typed directly at the REPL prompt,
|
|
or put in the ``main.py`` file. Here, we'll put in in ``main.py`` because to do
|
|
that we will learn how to go into safe mode.
|
|
|
|
At the moment the pyboard is acting as a serial USB device and an HID (a mouse).
|
|
So you cannot access the filesystem to edit your ``main.py`` file.
|
|
|
|
You also can't edit your ``boot.py`` to get out of HID-mode and back to normal
|
|
mode with a USB drive...
|
|
|
|
To get around this we need to go into *safe mode*. This was described in
|
|
the [safe mode tutorial](tut-reset), but we repeat the instructions here:
|
|
|
|
1. Hold down the USR switch.
|
|
2. While still holding down USR, press and release the RST switch.
|
|
3. The LEDs will then cycle green to orange to green+orange and back again.
|
|
4. Keep holding down USR until *only the orange LED is lit*, and then let
|
|
go of the USR switch.
|
|
5. The orange LED should flash quickly 4 times, and then turn off.
|
|
6. You are now in safe mode.
|
|
|
|
In safe mode, the ``boot.py`` and ``main.py`` files are not executed, and so
|
|
the pyboard boots up with default settings. This means you now have access
|
|
to the filesystem (the USB drive should appear), and you can edit ``main.py``.
|
|
(Leave ``boot.py`` as-is, because we still want to go back to HID-mode after
|
|
we finish editing ``main.py``.)
|
|
|
|
In ``main.py`` put the following code::
|
|
|
|
import pyb
|
|
|
|
switch = pyb.Switch()
|
|
accel = pyb.Accel()
|
|
hid = pyb.USB_HID()
|
|
|
|
while not switch():
|
|
hid.send((0, accel.x(), accel.y(), 0))
|
|
pyb.delay(20)
|
|
|
|
Save your file, eject/unmount your pyboard drive, and reset it using the RST
|
|
switch. It should now act as a mouse, and the angle of the board will move
|
|
the mouse around. Try it out, and see if you can make the mouse stand still!
|
|
|
|
Press the USR switch to stop the mouse motion.
|
|
|
|
You'll note that the y-axis is inverted. That's easy to fix: just put a
|
|
minus sign in front of the y-coordinate in the ``hid.send()`` line above.
|
|
|
|
Restoring your pyboard to normal
|
|
--------------------------------
|
|
|
|
If you leave your pyboard as-is, it'll behave as a mouse everytime you plug
|
|
it in. You probably want to change it back to normal. To do this you need
|
|
to first enter safe mode (see above), and then edit the ``boot.py`` file.
|
|
In the ``boot.py`` file, comment out (put a # in front of) the line with the
|
|
``VCP+HID`` setting, so it looks like::
|
|
|
|
#pyb.usb_mode('VCP+HID') # act as a serial device and a mouse
|
|
|
|
Save your file, eject/unmount the drive, and reset the pyboard. It is now
|
|
back to normal operating mode.
|