# SPDX-FileCopyrightText: 2017 Tony DiCola for Adafruit Industries
#
# SPDX-License-Identifier: 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
try:
from typing import List, Optional, Tuple
import busio
except ImportError:
# typing hint modules not needed or not available in CircuitPython
pass
from adafruit_bus_device import i2c_device
from micropython import const
__version__ = "0.0.0+auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_MPR121.git"
# Register addresses. Unused registers commented out to save memory.
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)
[docs]
class MPR121_Channel:
# pylint: disable=protected-access
"""Represents a single channel on the touch sensor.
Not meant to be used directly.
"""
_mpr121: "MPR121"
_channel: int
def __init__(self, mpr121: "MPR121", channel: int) -> None:
"""Creates a new ``MPR121_Channel`` instance.
:param mpr121: An instance of the touch sensor driver.
:param channel: The channel this instance represents (0-11).
"""
self._mpr121 = mpr121
self._channel = channel
@property
def value(self) -> bool:
"""Get whether the touch pad is being touched or not."""
return self._mpr121.touched() & (1 << self._channel) != 0
@property
def raw_value(self) -> int:
"""Get the raw touch measurement."""
return self._mpr121.filtered_data(self._channel)
@property
def threshold(self) -> int:
"""Get or set 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, new_thresh: int) -> None:
self._mpr121._write_register_byte(
MPR121_TOUCHTH_0 + 2 * self._channel, new_thresh
)
@property
def release_threshold(self) -> int:
"""Get or set 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, new_thresh: int) -> None:
self._mpr121._write_register_byte(
MPR121_RELEASETH_0 + 2 * self._channel, new_thresh
)
[docs]
class MPR121:
"""Driver for the MPR121 capacitive touch breakout board."""
_i2c: i2c_device.I2CDevice
_buffer: bytearray
_channels: List[Optional[MPR121_Channel]]
def __init__(self, i2c: busio.I2C, address: int = MPR121_I2CADDR_DEFAULT) -> None:
"""Creates a new ``MPR121`` instance.
:param i2c: An I2C driver.
:type i2c: class:`busio.I2C`
:param address: The address of the touch sensor (0x5A - 0x5D).
:type address: int
"""
self._i2c = i2c_device.I2CDevice(i2c, address)
self._buffer = bytearray(2)
self._channels = [None] * 12
self.reset()
def __getitem__(self, key: int) -> MPR121_Channel:
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) -> Tuple[bool]:
"""Get a tuple of the touched state for all pins."""
touched = self.touched()
return tuple(bool(touched >> i & 1) for i in range(12))
def _write_register_byte(self, register: int, value: int) -> None:
# 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: int, result: bytearray, length: Optional[int] = None
) -> 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)
[docs]
def reset(self) -> None:
"""Reset the MPR121 into a default state.
All configurations and states previously set are lost.
:raises RuntimeError: The sensor is in an invalid config state.
"""
# 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: int) -> int:
"""Get the filtered data register value.
:param pin: The pin to read (0 - 11).
:type pin: int
:raises ValueError: Argument ``pin`` is invalid.
:return: The filtered data value stored in the register.
:rtype: int
"""
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: int) -> int:
"""Get the baseline data register value.
:param pin: The pin to read (0 - 11).
:type pin: int
:raises ValueError: Argument ``pin`` is invalid.
:return: The baseline data value stored in the register.
:rtype: int
"""
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) -> int:
"""Get the touch state of all pins as a 12-bit value.
:return: A 12-bit value representing the touch state of each
pin. Each state in the value is represented by either a 1 or
0; touched or not.
:rtype: int
"""
self._read_register_bytes(MPR121_TOUCHSTATUS_L, self._buffer)
return ((self._buffer[1] << 8) | (self._buffer[0])) & 0xFFFF
[docs]
def is_touched(self, pin: int) -> bool:
"""Get if ``pin`` is being touched.
:raises ValueError: Argument ``pin`` is invalid.
:return: True if ``pin`` is being touched; otherwise False.
:rtype: bool
"""
if pin < 0 or pin > 11:
raise ValueError("Pin must be a value 0-11.")
touches = self.touched()
return (touches & (1 << pin)) > 0