The PyRuler is basically a Trinket M0 with extra LEDs and capacitive touch pads.
This demo program will let you turn the capacitive touch pads into a little keyboard. Three of the pads have a 'true' capacitive touch hardware interface, with the fourth we DIY a capacitive interface - we recommend using read_caps which will do all the nitty gritty for you.
The HID keyboard library is what emits keypresses. Note that Mac and Windows have different ways of typing special characters so you will have to set a WINDOWS_COMPUTER variable to match the host computer used!
import os
import board
from digitalio import DigitalInOut, Direction
import time
import touchio
# Set this to True to turn the touchpads into a keyboard
ENABLE_KEYBOARD = False
WINDOWS = "W"
MAC = "M"
LINUX = "L" # and Chrome OS
# Set your computer type to one of the above
OS = WINDOWS
# Used if we do HID output, see below
if ENABLE_KEYBOARD:
import usb_hid
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keycode import Keycode
from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
kbd = Keyboard(usb_hid.devices)
layout = KeyboardLayoutUS(kbd)
#print(dir(board), os.uname()) # Print a little about ourselves
led = DigitalInOut(board.D13)
led.direction = Direction.OUTPUT
touches = [DigitalInOut(board.CAP0)]
for p in (board.CAP1, board.CAP2, board.CAP3):
touches.append(touchio.TouchIn(p))
leds = []
for p in (board.LED4, board.LED5, board.LED6, board.LED7):
led = DigitalInOut(p)
led.direction = Direction.OUTPUT
led.value = True
time.sleep(0.25)
leds.append(led)
for led in leds:
led.value = False
cap_touches = [False, False, False, False]
def read_caps():
t0_count = 0
t0 = touches[0]
t0.direction = Direction.OUTPUT
t0.value = True
t0.direction = Direction.INPUT
# funky idea but we can 'diy' the one non-hardware captouch device by hand
# by reading the drooping voltage on a tri-state pin.
t0_count = t0.value + t0.value + t0.value + t0.value + t0.value + \
t0.value + t0.value + t0.value + t0.value + t0.value + \
t0.value + t0.value + t0.value + t0.value + t0.value
cap_touches[0] = t0_count > 2
cap_touches[1] = touches[1].raw_value > 3000
cap_touches[2] = touches[2].raw_value > 3000
cap_touches[3] = touches[3].raw_value > 3000
return cap_touches
def type_alt_code(code):
kbd.press(Keycode.ALT)
for c in str(code):
if c == '0':
keycode = Keycode.KEYPAD_ZERO
elif '1' <= c <= '9':
keycode = Keycode.KEYPAD_ONE + ord(c) - ord('1')
else:
raise RuntimeError("Only number codes permitted!")
kbd.press(keycode)
kbd.release(keycode)
kbd.release_all()
while True:
caps = read_caps()
print(caps)
# light up the matching LED
for i,c in enumerate(caps):
leds[i].value = c
if caps[0]:
if ENABLE_KEYBOARD:
if OS == WINDOWS:
type_alt_code(234)
elif OS == MAC:
kbd.send(Keycode.ALT, Keycode.Z)
elif OS == LINUX:
kbd.press(Keycode.CONTROL, Keycode.SHIFT)
kbd.press(Keycode.U)
kbd.release_all()
kbd.send(Keycode.TWO)
kbd.send(Keycode.ONE)
kbd.send(Keycode.TWO)
kbd.send(Keycode.SIX)
kbd.send(Keycode.ENTER)
if caps[1]:
if ENABLE_KEYBOARD:
if OS == WINDOWS:
type_alt_code(230)
elif OS == MAC:
kbd.send(Keycode.ALT, Keycode.M)
elif OS == LINUX:
kbd.press(Keycode.CONTROL, Keycode.SHIFT)
kbd.press(Keycode.U)
kbd.release_all()
kbd.send(Keycode.ZERO)
kbd.send(Keycode.THREE)
kbd.send(Keycode.B)
kbd.send(Keycode.C)
kbd.send(Keycode.ENTER)
if caps[2]:
if ENABLE_KEYBOARD:
if OS == WINDOWS:
type_alt_code(227)
elif OS == MAC:
kbd.send(Keycode.ALT, Keycode.P)
elif OS == LINUX:
kbd.press(Keycode.CONTROL, Keycode.SHIFT)
kbd.press(Keycode.U)
kbd.release_all()
kbd.send(Keycode.ZERO)
kbd.send(Keycode.THREE)
kbd.send(Keycode.C)
kbd.send(Keycode.ZERO)
kbd.send(Keycode.ENTER)
if caps[3]:
if ENABLE_KEYBOARD:
layout.write('https://www.digikey.com/python\n')
time.sleep(0.1)
Page last edited January 21, 2025
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