# MPR121 capacitive touch breakout driver. Port of Raspberry Pi/BeagleBone Black
# code from: https://github.com/adafruit/Adafruit_Python_MPR121/
# Author: Tony DiCola
# License: MIT License (https://opensource.org/licenses/MIT)
"""
`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
<https://www.adafruit.com/product/1982>`_ (Product ID: 1982)
* Adafruit `12 x Capacitive Touch Shield for Arduino - MPR121
<https://www.adafruit.com/product/2024>`_ (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
"""
import time
import adafruit_bus_device.i2c_device as i2c_device
from micropython import const
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_VL53L0X.git"
# Register addresses. Unused registers commented out to save memory.
# pylint: disable=bad-whitespace
MPR121_I2CADDR_DEFAULT = const(0x5A)
MPR121_TOUCHSTATUS_L = const(0x00)
#MPR121_TOUCHSTATUS_H = const(0x01)
MPR121_FILTDATA_0L = const(0x04)
#MPR121_FILTDATA_0H = const(0x05)
MPR121_BASELINE_0 = const(0x1E)
MPR121_MHDR = const(0x2B)
MPR121_NHDR = const(0x2C)
MPR121_NCLR = const(0x2D)
MPR121_FDLR = const(0x2E)
MPR121_MHDF = const(0x2F)
MPR121_NHDF = const(0x30)
MPR121_NCLF = const(0x31)
MPR121_FDLF = const(0x32)
MPR121_NHDT = const(0x33)
MPR121_NCLT = const(0x34)
MPR121_FDLT = const(0x35)
MPR121_TOUCHTH_0 = const(0x41)
MPR121_RELEASETH_0 = const(0x42)
MPR121_DEBOUNCE = const(0x5B)
MPR121_CONFIG1 = const(0x5C)
MPR121_CONFIG2 = const(0x5D)
#MPR121_CHARGECURR_0 = const(0x5F)
#MPR121_CHARGETIME_1 = const(0x6C)
MPR121_ECR = const(0x5E)
#MPR121_AUTOCONFIG0 = const(0x7B)
#MPR121_AUTOCONFIG1 = const(0x7C)
#MPR121_UPLIMIT = const(0x7D)
#MPR121_LOWLIMIT = const(0x7E)
#MPR121_TARGETLIMIT = const(0x7F)
#MPR121_GPIODIR = const(0x76)
#MPR121_GPIOEN = const(0x77)
#MPR121_GPIOSET = const(0x78)
#MPR121_GPIOCLR = const(0x79)
#MPR121_GPIOTOGGLE = const(0x7A)
MPR121_SOFTRESET = const(0x80)
# pylint: enable=bad-whitespace
[docs]class MPR121_Channel():
# pylint: disable=protected-access
"""Helper class to represent a touch channel on the MPR121. Not meant to
be used directly."""
def __init__(self, mpr121, channel):
self._mpr121 = mpr121
self._channel = channel
@property
def value(self):
"""Whether the touch pad is being touched or not."""
return self._mpr121.touched() & (1 << self._channel) != 0
@property
def raw_value(self):
"""The raw touch measurement."""
return self._mpr121.filtered_data(self._channel)
@property
def threshold(self):
"""The touch threshold."""
buf = bytearray(1)
self._mpr121._read_register_bytes(MPR121_TOUCHTH_0 + 2*self._channel, buf, 1)
return buf[0]
@threshold.setter
def threshold(self, value):
self._mpr121._write_register_byte(MPR121_TOUCHTH_0 + 2*self._channel, value)
@property
def release_threshold(self):
"""The release threshold."""
buf = bytearray(1)
self._mpr121._read_register_bytes(MPR121_RELEASETH_0 + 2*self._channel, buf, 1)
return buf[0]
@release_threshold.setter
def release_threshold(self, value):
self._mpr121._write_register_byte(MPR121_RELEASETH_0 + 2*self._channel, value)
[docs]class MPR121:
"""Driver for the MPR121 capacitive touch breakout board."""
def __init__(self, i2c, address=MPR121_I2CADDR_DEFAULT):
self._i2c = i2c_device.I2CDevice(i2c, address)
self._buffer = bytearray(2)
self._channels = [None]*12
self.reset()
def __getitem__(self, key):
if key < 0 or key > 11:
raise IndexError('Pin must be a value 0-11.')
if self._channels[key] is None:
self._channels[key] = MPR121_Channel(self, key)
return self._channels[key]
@property
def touched_pins(self):
"""A tuple of touched state for all pins."""
touched = self.touched()
return tuple([bool(touched >> i & 0x01) for i in range(12)])
def _write_register_byte(self, register, value):
# Write a byte value to the specifier register address.
# MPR121 must be put in Stop Mode to write to most registers
stop_required = True
if register == MPR121_ECR or 0x73 <= register <= 0x7A:
stop_required = False
with self._i2c:
if stop_required:
self._i2c.write(bytes([MPR121_ECR, 0x00]))
self._i2c.write(bytes([register, value]))
if stop_required:
self._i2c.write(bytes([MPR121_ECR, 0x8F]))
def _read_register_bytes(self, register, result, length=None):
# Read the specified register address and fill the specified result byte
# array with result bytes. Make sure result buffer is the desired size
# of data to read.
if length is None:
length = len(result)
with self._i2c:
self._i2c.write_then_readinto(bytes([register]), result,
in_end=length, stop=False)
[docs] def reset(self):
"""Reset the MPR121 into a default state ready to detect touch inputs.
"""
# Write to the reset register.
self._write_register_byte(MPR121_SOFTRESET, 0x63)
time.sleep(0.001) # This 1ms delay here probably isn't necessary but can't hurt.
# Set electrode configuration to default values.
self._write_register_byte(MPR121_ECR, 0x00)
# Check CDT, SFI, ESI configuration is at default values.
self._read_register_bytes(MPR121_CONFIG2, self._buffer, 1)
if self._buffer[0] != 0x24:
raise RuntimeError('Failed to find MPR121 in expected config state!')
# Default touch and release thresholds
for i in range(12):
self._write_register_byte(MPR121_TOUCHTH_0 + 2*i, 12)
self._write_register_byte(MPR121_RELEASETH_0 + 2*i, 6)
# Configure baseline filtering control registers.
self._write_register_byte(MPR121_MHDR, 0x01)
self._write_register_byte(MPR121_NHDR, 0x01)
self._write_register_byte(MPR121_NCLR, 0x0E)
self._write_register_byte(MPR121_FDLR, 0x00)
self._write_register_byte(MPR121_MHDF, 0x01)
self._write_register_byte(MPR121_NHDF, 0x05)
self._write_register_byte(MPR121_NCLF, 0x01)
self._write_register_byte(MPR121_FDLF, 0x00)
self._write_register_byte(MPR121_NHDT, 0x00)
self._write_register_byte(MPR121_NCLT, 0x00)
self._write_register_byte(MPR121_FDLT, 0x00)
# Set other configuration registers.
self._write_register_byte(MPR121_DEBOUNCE, 0)
self._write_register_byte(MPR121_CONFIG1, 0x10) # default, 16uA charge current
self._write_register_byte(MPR121_CONFIG2, 0x20) # 0.5uS encoding, 1ms period
# Enable all electrodes.
self._write_register_byte(MPR121_ECR, 0x8F) # start with first 5 bits of baseline tracking
[docs] def filtered_data(self, pin):
"""Return filtered data register value for the provided pin (0-11).
Useful for debugging.
"""
if pin < 0 or pin > 11:
raise ValueError('Pin must be a value 0-11.')
self._read_register_bytes(MPR121_FILTDATA_0L + pin*2, self._buffer)
return ((self._buffer[1] << 8) | (self._buffer[0])) & 0xFFFF
[docs] def baseline_data(self, pin):
"""Return baseline data register value for the provided pin (0-11).
Useful for debugging.
"""
if pin < 0 or pin > 11:
raise ValueError('Pin must be a value 0-11.')
self._read_register_bytes(MPR121_BASELINE_0 + pin, self._buffer, 1)
return self._buffer[0] << 2
[docs] def touched(self):
"""Return touch state of all pins as a 12-bit value where each bit
represents a pin, with a value of 1 being touched and 0 not being touched.
"""
self._read_register_bytes(MPR121_TOUCHSTATUS_L, self._buffer)
return ((self._buffer[1] << 8) | (self._buffer[0])) & 0xFFFF
[docs] def is_touched(self, pin):
"""Return True if the specified pin is being touched, otherwise returns
False.
"""
if pin < 0 or pin > 11:
raise ValueError('Pin must be a value 0-11.')
touches = self.touched()
return (touches & (1 << pin)) > 0