Dependencies¶
This driver depends on:
Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle.
Usage Example¶
See usage in the examples/mpr121_simpletest.py file.
Contributing¶
Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.
Building locally¶
To build this library locally you’ll need to install the circuitpython-build-tools package.
python3 -m venv .env
source .env/bin/activate
pip install circuitpython-build-tools
Once installed, make sure you are in the virtual environment:
source .env/bin/activate
Then run the build:
circuitpython-build-bundles --filename_prefix adafruit-circuitpython-mpr121 --library_location .
Sphinx documentation¶
Sphinx is used to build the documentation based on rST files and comments in the code. First, install dependencies (feel free to reuse the virtual environment from above):
python3 -m venv .env
source .env/bin/activate
pip install Sphinx sphinx-rtd-theme
Now, once you have the virtual environment activated:
cd docs
sphinx-build -E -W -b html . _build/html
This will output the documentation to docs/_build/html. Open the index.html in your browser to
view them. It will also (due to -W) error out on any warning like Travis will. This is a good way to
locally verify it will pass.
Table of Contents¶
Simple test¶
Ensure your device works with this simple test.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | # Simple test of the MPR121 capacitive touch sensor library.
# Will print out a message when any of the 12 capacitive touch inputs of the
# board are touched. Open the serial REPL after running to see the output.
# Author: Tony DiCola
import time
import board
import busio
# Import MPR121 module.
import adafruit_mpr121
# Create I2C bus.
i2c = busio.I2C(board.SCL, board.SDA)
# Create MPR121 class.
mpr121 = adafruit_mpr121.MPR121(i2c)
# Note you can optionally change the address of the device:
#mpr121 = adafruit_mpr121.MPR121(i2c, address=0x91)
# Loop forever testing each input and printing when they're touched.
while True:
# Loop through all 12 inputs (0-11).
for i in range(12):
# Call is_touched and pass it then number of the input. If it's touched
# it will return True, otherwise it will return False.
if mpr121.is_touched(i):
print('Input {} touched!'.format(i))
time.sleep(0.25) # Small delay to keep from spamming output messages.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 | # MPR121 piano demo.
# Listens to the first 7 inputs of the MPR121 and plays a middle scale note
# when an input is touched. Note only one note is played at a time!
# Author: Tony DiCola
import time
import board
import busio
import pulseio
# Import MPR121 module.
import adafruit_mpr121
# Configure PWM buzzer and other state:
BUZZER_PIN = board.D9
TONE_ON_DUTY = 2**15 # Duty cycle of tone when turned on, a square wave.
TONE_OFF_DUTY = 0 # Duty cycle of tone when turned off, 0 or no signal.
NOTE_FREQS = [261, # Input 0 = 261 hz = middle C
294, # Input 1 = middle D
329, # Input 2 = middle E
349, # Input 3 = middle F
392, # Input 4 = middle G
440, # Input 5 = middle A
493, # Input 6 = middle B
0, # Input 7 = nothing (set to a frequency in hertz!)
0, # Input 8
0, # Input 9
0, # Input 10
0] # Input 11
# Create I2C bus.
i2c = busio.I2C(board.SCL, board.SDA)
# Create MPR121 class.
mpr121 = adafruit_mpr121.MPR121(i2c)
# Note you can optionally change the address of the device:
#mpr121 = adafruit_mpr121.MPR121(i2c, address=0x91)
# Setup buzzer PWM output.
buzzer = pulseio.PWMOut(BUZZER_PIN, duty_cycle=TONE_OFF_DUTY, frequency=440,
variable_frequency=True)
# Main loop.
# First grab an initial touch state for all of the inputs. The touched()
# function can quickly get the state of all input pins and returns them as a
# 12-bit value with a bit set to 1 for each appropriate input (i.e. bit 0 is
# input 0, bit 1 is input 1, etc.)
last = mpr121.touched()
while True:
# Every loop iteration get an updated touch state and look to see if it
# changed since the last iteration.
current = mpr121.touched()
if last != current:
# Some pin changed, turn off playback and look for any touched pins.
buzzer.duty_cycle = TONE_OFF_DUTY
# Loop through all 12 inputs (0-11) and look at their bits in the
# current touch state. A bit that's set is touched!
for i in range(12):
if (1 << i) & current > 0:
print('Input {} touched!'.format(i))
# Grab the frequency for the associated pin and check that it's
# not zero (unused).
freq = NOTE_FREQS[i]
if freq != 0:
# Pin with a specified frequency was touched, play the tone!
buzzer.frequency = NOTE_FREQS[i]
buzzer.duty_cycle = TONE_ON_DUTY
# Update touch state and delay a bit before next loop iteration.
last = current
time.sleep(0.01)
|
adafruit_mpr121¶
CircuitPython driver for the MPR121 capacitive touch breakout board.
See usage in the examples/simpletest.py file.
- Author(s): Tony DiCola
Implementation Notes¶
Hardware:
- Adafruit 12-Key Capacitive Touch Sensor Breakout - MPR121 (Product ID: 1982)
- Adafruit 12 x Capacitive Touch Shield for Arduino - MPR121 (Product ID: 2024)
Software and Dependencies:
- Adafruit CircuitPython firmware for the ESP8622 and M0-based boards: https://github.com/adafruit/circuitpython/releases
- Adafruit’s Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
-
class
adafruit_mpr121.MPR121(i2c, address=90)[source]¶ Driver for the MPR121 capacitive touch breakout board.
-
baseline_data(pin)[source]¶ Return baseline data register value for the provided pin (0-11). Useful for debugging.
-
filtered_data(pin)[source]¶ Return filtered data register value for the provided pin (0-11). Useful for debugging.
-
is_touched(pin)[source]¶ Return True if the specified pin is being touched, otherwise returns False.
-