Program the Circuit Playground Express!

The CPX has an on-board compiler, which means you can program it in (pretty much) any language you want! I opted for CircuitPython, a version of Python for microcontrollers, 'cause Python is awesome.

Here's the GitHub repository that has the full code. The same code is embeded below, simply click the Download link to save as main.py on your CIRCUITPY drive on the CPX

# Minecraft Gesture Controller
#
# Written by <[email protected]>
# MIT License V.asof2018
# Also coffee/beer ware license :)
# Super awesome thanks to:
# Richard Albritton, Tony DiCola, John Parker
# All the awesome people who wrote the libraries

# Libraries


import time

# Libraries for accelerometer
import adafruit_lis3dh
import board
import busio
# General purpose libraries
import touchio
# Libraries for HID Keyboard & Mouse
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
from adafruit_hid.keycode import Keycode
from adafruit_hid.mouse import Mouse

# CPX Setup
touch_a1 = touchio.TouchIn(board.A1)
touch_a1.threshold = 2000
touch_a2 = touchio.TouchIn(board.A2)
touch_a2.threshold = 2000
touch_a3 = touchio.TouchIn(board.A3)
touch_a3.threshold = 2000
touch_a4 = touchio.TouchIn(board.A4)
touch_a4.threshold = 2000

# Keyboard & Mouse Setup

# The keyboard object!
kbd = Keyboard()
# we're americans :)
layout = KeyboardLayoutUS(kbd)
# The mouse object!
mouse = Mouse()

# Accelerometer Setup

# Initialize Accelerometer
i2c = busio.I2C(board.ACCELEROMETER_SCL, board.ACCELEROMETER_SDA)
lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c, address=25)
# Set range of accelerometer
# (can be RANGE_2_G, RANGE_4_G, RANGE_8_G or RANGE_16_G).
lis3dh.range = adafruit_lis3dh.RANGE_8_G


# Controller Functions

# A helper to 'remap' an input range to an output range
def Map(x, in_min, in_max, out_min, out_max):
    return int(
        (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min
    )


def Move(upDown_axis, isBackward):
    axis_new = abs(upDown_axis)
    # If you are touching A4, walk backwards, else walk forwards
    if isBackward:
        print("backwards")  # Debugging
        if axis_new > 1.2:  # walk threshold
            if axis_new > 2.5:  # run threshold
                kbd.press(Keycode.LEFT_CONTROL, Keycode.S)
                time.sleep(0.1)
                kbd.release_all()
            else:
                kbd.press(Keycode.S)
                time.sleep(0.1)
            kbd.release_all()
    else:
        if axis_new > 1.2:  # walk threshold
            if axis_new > 2.5:  # run threshold
                kbd.press(Keycode.LEFT_CONTROL)
                time.sleep(0.1)
                kbd.release_all()
            else:
                kbd.press(Keycode.W)
                time.sleep(0.1)
            kbd.release_all()


def Turn(upDown_axis, leftRight_axis, lookUp):
    leftRight_adj = int(leftRight_axis)  # currently z_axis
    upDown_adj = int(upDown_axis)  # currently y_axis

    leftRight_new = Map(leftRight_adj, -3, 3, -100, 100)
    if lookUp and abs(upDown_adj) < 1.2:
        upDown_new = Map(upDown_adj, -1, 1, -100, 100)
    else:
        upDown_new = 0
    if abs(leftRight_new) < 127:
        mouse.move(-leftRight_new, upDown_new)
    else:
        mouse.move(0, 0)


def Jump(upDown_axis):
    upDown = abs(upDown_axis)
    if upDown > 3:
        kbd.press(Keycode.SPACE, Keycode.W)
    kbd.release_all()


def Give(upDown_axis, frontBack_axis):
    frontBack_new = abs(frontBack_axis)
    if abs(upDown_axis) < 1:
        if frontBack_new > 2:
            print("give")
            mouse.click(Mouse.RIGHT_BUTTON)
            mouse.release_all()


def Attack():
    """Attack! By clicking the left mouse button"""
    print("attack")
    mouse.click(Mouse.LEFT_BUTTON)
    time.sleep(0.1)
    mouse.release_all()


def Inventory():
    """Open up inventory, press the E keyboard key"""
    print("inventory")  # Debugging -- view in serial monitor
    kbd.press(Keycode.E)
    time.sleep(0.01)
    kbd.release_all()


def ESC():
    """Escape by pressing the ESCape key"""
    print("ESC")  # Debugging -- view in serial monitor
    kbd.press(Keycode.ESCAPE)
    time.sleep(0.01)
    kbd.release_all()


def readAxes():
    """Convert acceleration from m/s^2 to G, with a delay"""
    x, y, z = lis3dh.acceleration
    time.sleep(0.01)
    return (x / 9.806, y / 9.806, z / 9.806)  # 9.806 m/s^2 per G


# Main Function
while True:
    # Read accelerometer values (in G).  Returns a 3-tuple of x, y, x axis
    pos_x, pos_y, pos_z = readAxes()

    # Read finger pads and act accordingly
    if touch_a1.value:
        Attack()

    if touch_a2.value:
        Inventory()

    if touch_a3.value:
        ESC()

    is_backward = touch_a4.value
    look_up = touch_a4.value

    # Run through the motions! .. literally :)
    Move(pos_y, is_backward)
    Turn(pos_y, pos_z, look_up)
    Jump(pos_y)
    Give(pos_y, pos_x)

    # Small delay to keep things responsive but
    # give time for interrupt processing.
    time.sleep(0.01)

    # Debugging Ahead!!
    # Use the following 2 lines to figure out which
    # axis is upDown, frontBack, or LeftRight
    # and also for debugging!
    # print('x = {}G, y = {}G, z = {}G'.format(x, y, z))
    # time.sleep(0.3)
Keep readin' if you want to understand how the program works (definitely suggested) or if you want to modify the code.

Required Libraries

To do the things we want with our controller, we need the following CircuitPython libraries. All are available in the bundle, you can learn how to install it here.

  • LIS3DH accelerometer
    • This allows us to use motion to trigger various things.
  • Human Interface Device ("HID") keyboard
    • This library allows us to control the keyboard!
  • HID mouse
    • This library means we can control the mouse!
  • CPX capacitive touch
    • This library lets us use the capacitive touch feature on the CPX, hooray!
  • A couple of other libraries to make our lives easier: timebusio, and board.
##########################
##        Libraries     ##
##########################
import touchio
import board
import busio
import time
#Libraries for HID Keyboard & Mouse
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keycode import Keycode
from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
from adafruit_hid.mouse import Mouse
#Libraries for accelerometer
import adafruit_lis3dh

Configure and initialize the libraries

Assign variables for the keyboard, mouse, and accelerometer objects. Select a range for the accelerometer.

#######################
#     CPX Setup       #
#######################
touch_a1 = touchio.TouchIn(board.A1)
touch_a1.threshold = 2000
touch_a2 = touchio.TouchIn(board.A2)
touch_a2.threshold = 2000
touch_a3 = touchio.TouchIn(board.A3)
touch_a3.threshold = 2000
touch_a4 = touchio.TouchIn(board.A4)
touch_a4.threshold = 2000
 
############################
# Keyboard & Mouse Setup   #
############################
# The keyboard object!
kbd = Keyboard()
# we're americans :)
layout = KeyboardLayoutUS(kbd)
#The mouse object! 
mouse = Mouse()
 
#######################
# Accelerometer Setup #
#######################
#Initialize Accelerometer
i2c = busio.I2C(board.ACCELEROMETER_SCL, board.ACCELEROMETER_SDA)
lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c, address=25)
# Set range of accelerometer (can be RANGE_2_G, RANGE_4_G, RANGE_8_G or RANGE_16_G).
lis3dh.range = adafruit_lis3dh.RANGE_8_G

Write short functions for each of the controls

The motion controls can be tricky. We did some initial testing with the accelerometer by printing the values in a serial monitor (in the source code, go to the 'main loop' while True: section and uncomment the two debugging lines). This will help you to determine thresholds for walking, running and jumping, looking left and right, and placing objects.

The touch pad triggers are much easier as you are only looking for a capacitive trigger (True/False) when you read the touch_an.value

Remember to release all of the keyboard and mouse keys at the end of each function! Otherwise you'll end up with stuck keys, in which case you can always unplug the USB cable

This guide was first published on Feb 19, 2018. It was last updated on Sep 20, 2018. This page (Program the Circuit Playground Express!) was last updated on Feb 19, 2018.