HackSpace_-_April_2020

LENS

• if you’re a Frogger/Bunner aficionado, you may
  wish to implement this as well).
  Reading the accelerometer is as easy as importing
  the appropriate module and running one line:

from adafruit_circuitplayground import cp

x, y, z = cp.acceleration

Sending key presses is similarly easy. You can set up
a keyboard with the following:

from adafruit_hid.keyboard import Keyboard

from adafruit_hid.keyboard_layout_us import

KeyboardLayoutUS

from adafruit_hid.keycode import Keycode

keyboard = Keyboard(usb_hid.devices)

Then send key presses with code such as this:

time.keyboard.press(Keycode.LEFT_ARROW)

time.sleep(0.1)

keyboard.release_all()

The only thing left is to slot in our mechanics. The
X-axis on the accelerometer can determine if the
controller is tilted left or right. The output is between
10 (all the way left) and -10 (all the way right). We
chose to threshold it at 7 and -7 to require the user
to tilt it most of the way. There’s a little bit of fuzz
in the readings, especially as the user flicks the
controller up, so having a high threshold helps avoid
erroneous readings.
The Y-axis is for jumping. In this case, we require
a ‘flap’ where the user first lifts it up (over a
threshold of 5), then back down again.
The full code for our controller is:
import time
from adafruit_circuitplayground import cp
import usb_hid
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keyboard_layout_us import
KeyboardLayoutUS
from adafruit_hid.keycode import Keycode

keyboard = Keyboard(usb_hid.devices)

jumping = 0

up=False

while True:

x, y, z = cp.acceleration

if abs(y) > 5:

up=True

if y < 5 and up:

keyboard.press(Keycode.UP_ARROW)

time.sleep(0.3)

keyboard.release_all()

up=False

if x < -7 :

keyboard.press(Keycode.LEFT_ARROW)

time.sleep(0.1)

keyboard.release_all()

if x > 7 :

keyboard.press(Keycode.RIGHT_ARROW)

time.sleep(0.1)

keyboard.release_all()

time.sleep(0.1)

if jumping > 0: jumping=jumping-1

The final challenge we had was that there’s a bit of

wobble when moving the controller around –

especially when trying to jump repeatedly and

quickly. After fiddling with thresholds for a while, we

found that there’s a much simpler solution: increase

the weight of the controller. The easiest way to do

this is to place it inside a book. If you’ve ever held a

copy of Code the Classics, you’ll know that it’s a

fairly weighty tome. Just place the board inside and

close the book around it, and all the jitter disappears.

That’s all there is to the controller. You can use it to

play the game, just as you would any joypad. Start

the game as usual, then start flapping the book

around to get hopping.

Above

It doesn’t take

much CircuitPython

to convert a

microcontroller into

a games controller

Below

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