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mcp23017_scanner.py
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mcp23017_scanner.py
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# SPDX-FileCopyrightText: 2017 Scott Shawcroft, written for Adafruit Industries
# SPDX-FileCopyrightText: Copyright (c) 2022 Neradoc
#
# SPDX-License-Identifier: MIT
"""
`mcp23017_scanner`
================================================================================
Scan a matrix keyboard with an API modelled after the keypad module
* Author(s): Neradoc
Implementation Notes
--------------------
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the supported boards:
https://circuitpython.org/downloads
"""
from digitalio import DigitalInOut, Pull
from supervisor import ticks_ms
try:
# Only used for typing
from typing import Tuple, Optional, Iterable, Set
from microcontroller import Pin
except ImportError:
pass
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/Neradoc/CircuitPython_mcp23017_scanner.git"
class Event:
"""
A key transition event.
:param int key_number: the key number
:param bool pressed: ``True`` if the key was pressed; ``False`` if it was released.
:param int timestamp: The time in milliseconds that the keypress occurred in the
`supervisor.ticks_ms` time system. If specified as None,
the current value of `supervisor.ticks_ms` is used.
"""
def __init__(self, key: int, pressed: bool, timestamp: int = None):
self.key_number = key
"""The key number."""
self.timestamp = timestamp or ticks_ms()
"""The timestamp."""
self.pressed = pressed
"""True if the event represents a key down (pressed) transition.
The opposite of released."""
@property
def released(self) -> bool:
"""True if the event represents a key up (released) transition.
The opposite of pressed."""
return not self.pressed
def __eq__(self, other: object) -> bool:
"""Two Event objects are equal if their key_number and pressed/released values
are equal. Note that this does not compare the event timestamps."""
return self.key_number == other.key_number and self.pressed == other.pressed
def __hash__(self) -> int:
"""Returns a hash for the Event, so it can be used in dictionaries, etc..
Note that as events with different timestamps compare equal,
they also hash to the same value."""
return self.key_number << 1 + int(self.pressed)
class EventQueue:
"""
A queue of Event objects, filled by a scanner.
"""
def __init__(self): # , max_events=64):
self._outq = []
self._inq = []
def append(self, event: Event) -> None:
"""Append an event at the end of the queue"""
self._inq.append(event)
def get(self) -> Event:
"""
Return the next key transition event.
Return None if no events are pending.
"""
if self._outq:
return self._outq.pop()
if len(self._inq) == 1:
return self._inq.pop()
if self._inq:
self._outq = list(reversed(self._inq))
self._inq.clear()
return self._outq.pop()
return None
def get_into(self, event: Event) -> bool:
"""
Store the next key transition event in the supplied event, if available,
and return True. If there are no queued events, do not touch event
and return False.
Note: in python this does not optimize to avoid allocating.
"""
next_event = self.get()
if next_event:
event.key_number = next_event.key_number
event.timestamp = next_event.timestamp
event.pressed = next_event.pressed
return True
return False
def clear(self) -> None:
"""Clear any queued key transition events."""
self._outq.clear()
self._inq.clear()
def __bool__(self) -> bool:
"""
True if len() is greater than zero.
This is an easy way to check if the queue is empty.
"""
return len(self) > 0
def __len__(self) -> int:
"""
Return the number of events currently in the queue.
Used to implement len().
"""
return len(self._outq) + len(self._inq)
class McpScanner:
"""
Base class for MCP scanners.
.. property:: events
The `EventQueue` associated with this Scanner. (read-only)
"""
def __init__(
self,
mcp: any,
irq: Optional[Pin] = None,
):
self._key_count = 0
self.mcp = mcp
self.keys_state = set()
self.events = EventQueue()
self.irq = None
if irq:
self.irq = DigitalInOut(irq)
self.irq.switch_to_input(Pull.UP)
@property
def key_count(self) -> int:
"""The number of keys that are being scanned. (read-only)"""
return self._key_count
def _scan_pins(self) -> Set[int]: # pylint:disable=no-self-use
return Set()
def update(self) -> None:
"""
Run the scan and create events in the event queue.
"""
timestamp = ticks_ms()
# scan the matrix, find Neo
current_state = self._scan_pins()
# use set algebra to find released and pressed keys
released_keys = self.keys_state - current_state
pressed_keys = current_state - self.keys_state
# create the events into the queue
for key in released_keys:
self.events.append(Event(key, False, timestamp))
for key in pressed_keys:
self.events.append(Event(key, True, timestamp))
# end
self.keys_state = current_state
def reset(self) -> None:
"""
Reset the internal state of the scanner to assume that all keys are now
released. Any key that is already pressed at the time of this call will
therefore cause a new key-pressed event to occur on the next scan.
"""
self.events.clear()
self.keys_state.clear()
def deinit(self) -> None:
"""Release the IRQ pin"""
if self.irq:
self.irq.deinit()
self.irq = None
# TODO: reset the mcp configuration
def __enter__(self) -> "McpScanner":
"""No-op used by Context Managers."""
return self
def __exit__(self, type_er, value, traceback) -> None:
"""Automatically deinitializes when exiting a context."""
self.deinit()
class McpMatrixScanner(McpScanner):
"""
Class to scan a matrix of keys connected to the MCP chip.
Columns are on port A and inputs.
Rows are on port B and outputs.
"""
def __init__(
self,
mcp: any,
row_pins: Iterable[int],
column_pins: Iterable[int],
irq: Optional[Pin] = None,
):
super().__init__(mcp, irq)
self._key_count = len(column_pins) * len(row_pins)
self.columns = column_pins
self.rows = row_pins
# set port A to output (columns)
mcp.iodira = 0x00
# set port B to input (rows) all pull ups
mcp.iodirb = 0xFF
mcp.gppub = 0xFF
# set interrupts
if irq:
# TODO: configure mcp based on row and column numbers
# to leave the other pins free to use ?
mcp.interrupt_enable = 0xFF00
mcp.default_value = 0xFFFF
# compare input to default value (1) or previous value (0)
mcp.interrupt_configuration = 0xFF00
mcp.io_control = 0x44 # Interrupt as open drain and mirrored
mcp.clear_ints()
def _scan_pins(self) -> Set[int]:
"""Scan the matrix and return the list of keys down"""
pressed = set()
num_cols = len(self.columns)
for scan_column in self.columns:
# set all outputs to 1 on port A except the scan_column
self.mcp.gpioa = 0xFF - (1 << scan_column)
if self.irq is None or not self.irq.value:
# read the input
inputs = self.mcp.gpiob
if inputs:
# adds (columns,row) if the row is 0 too
for row in self.rows:
if (inputs >> row) & 1 == 0:
pressed.add(scan_column + num_cols * row)
# set back port A to default
self.mcp.gpioa = 0xFF
return pressed
def key_number_to_row_column(self, key_number: int) -> Tuple[int]:
"""Convert key number to row, column"""
row = key_number // len(self.columns)
column = key_number % len(self.columns)
return (row, column)
def row_column_to_key_number(self, row: int, column: int) -> int:
"""Convert row, column to key number"""
return row * len(self.columns) + column
class McpKeysScanner(McpScanner):
"""
Class to scan a key per pin of the MCP chip.
Pins 0-7 are on port A. Pins 8-15 are on port B.
"""
def __init__(
self,
mcp: any,
pins: Iterable[int],
irq: Optional[Pin] = None,
):
super().__init__(mcp, irq)
self._key_count = len(pins)
self.pins = pins
self.pin_bits = sum(1 << x for x in pins)
# set port A and B to input all pull ups
mcp.iodir = 0xFFFF & self.pin_bits
mcp.gppu = 0xFFFF & self.pin_bits
# set interrupts
if irq:
# set interrupts
mcp.interrupt_enable = 0xFFFF & self.pin_bits
mcp.default_value = 0xFFFF & self.pin_bits
# compare input to default value (1) or previous value (0)
mcp.interrupt_configuration = 0xFFFF & self.pin_bits
mcp.io_control = 0x44 # Interrupt as open drain and mirrored
mcp.clear_ints()
def _scan_pins(self) -> Set[int]:
"""Scan the buttons and return the list of keys down"""
pressed = set()
inputs = self.mcp.gpio & self.pin_bits
for pin in self.pins:
if inputs & (1 << pin) == 0:
pressed.add(pin)
return pressed