Merge pull request #34 from prplz/main

Use adafruit ticks library

README.rst

@@ -23,6 +23,7 @@ Dependencies
 This driver depends on:
 
 * `Adafruit CircuitPython <https://github.com/adafruit/circuitpython>`_
+* `Adafruit Ticks <https://github.com/adafruit/Adafruit_CircuitPython_Ticks>`_
 
 Please ensure all dependencies are available on the CircuitPython filesystem.
 This is easily achieved by downloading

adafruit_debouncer.py

@@ -15,45 +15,27 @@
 Implementation Notes
 --------------------
 
-**Hardware:**
-
-Not all hardware / CircuitPython combinations are capable of running the
-debouncer correctly for an extended length of time.  If this line works
-on your microcontroller, then the debouncer should work forever:
-
-``from time import monotonic_ns``
-
-If it gives an ImportError, then the time values available in Python become
-less accurate over the days, and the debouncer will take longer to react to
-button presses.
-
 **Software and Dependencies:**
 
 * Adafruit CircuitPython firmware for the supported boards:
   https://github.com/adafruit/circuitpython/releases
+* Adafruit Ticks library:
+  https://github.com/adafruit/Adafruit_CircuitPython_Ticks
 """
 
 # imports
 
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_Debouncer.git"
 
-import time
+from adafruit_ticks import ticks_ms, ticks_diff
 from micropython import const
 
 _DEBOUNCED_STATE = const(0x01)
 _UNSTABLE_STATE = const(0x02)
 _CHANGED_STATE = const(0x04)
 
-# Find out whether the current CircuitPython really supports time.monotonic_ns(),
-# which doesn't have the accuracy limitation.
-try:
-    time.monotonic_ns()
-    TICKS_PER_SEC = 1_000_000_000
-    MONOTONIC_TICKS = time.monotonic_ns
-except (AttributeError, NotImplementedError):
-    TICKS_PER_SEC = 1
-    MONOTONIC_TICKS = time.monotonic
+_TICKS_PER_SEC = const(1000)
 
 
 class Debouncer:
@@ -77,7 +59,7 @@ def __init__(self, io_or_predicate, interval=0.010):
 
         # Could use the .interval setter, but pylint prefers that we explicitly
         # set the real underlying attribute:
-        self._interval_ticks = interval * TICKS_PER_SEC
+        self._interval_ticks = interval * _TICKS_PER_SEC
 
     def _set_state(self, bits):
         self.state |= bits
@@ -93,29 +75,31 @@ def _get_state(self, bits):
 
     def update(self):
         """Update the debouncer state. MUST be called frequently"""
-        now_ticks = MONOTONIC_TICKS()
+        now_ticks = ticks_ms()
         self._unset_state(_CHANGED_STATE)
         current_state = self.function()
         if current_state != self._get_state(_UNSTABLE_STATE):
             self._last_bounce_ticks = now_ticks
             self._toggle_state(_UNSTABLE_STATE)
         else:
-            if now_ticks - self._last_bounce_ticks >= self._interval_ticks:
+            if ticks_diff(now_ticks, self._last_bounce_ticks) >= self._interval_ticks:
                 if current_state != self._get_state(_DEBOUNCED_STATE):
                     self._last_bounce_ticks = now_ticks
                     self._toggle_state(_DEBOUNCED_STATE)
                     self._set_state(_CHANGED_STATE)
-                    self._last_duration_ticks = now_ticks - self._state_changed_ticks
+                    self._last_duration_ticks = ticks_diff(
+                        now_ticks, self._state_changed_ticks
+                    )
                     self._state_changed_ticks = now_ticks
 
     @property
     def interval(self):
         """The debounce delay, in seconds"""
-        return self._interval_ticks / TICKS_PER_SEC
+        return self._interval_ticks / _TICKS_PER_SEC
 
     @interval.setter
     def interval(self, new_interval_s):
-        self._interval_ticks = new_interval_s * TICKS_PER_SEC
+        self._interval_ticks = new_interval_s * _TICKS_PER_SEC
 
     @property
     def value(self):
@@ -137,9 +121,9 @@ def fell(self):
     @property
     def last_duration(self):
         """Return the number of seconds the state was stable prior to the most recent transition."""
-        return self._last_duration_ticks / TICKS_PER_SEC
+        return self._last_duration_ticks / _TICKS_PER_SEC
 
     @property
     def current_duration(self):
         """Return the number of seconds since the most recent transition."""
-        return (MONOTONIC_TICKS() - self._state_changed_ticks) / TICKS_PER_SEC
+        return ticks_diff(ticks_ms(), self._state_changed_ticks) / _TICKS_PER_SEC

requirements.txt

@@ -3,3 +3,4 @@
 # SPDX-License-Identifier: Unlicense
 
 Adafruit-Blinka
+adafruit-circuitpython-ticks

setup.py

@@ -36,6 +36,7 @@
     author_email="circuitpython@adafruit.com",
     install_requires=[
         "Adafruit-Blinka",
+        "adafruit-circuitpython-ticks",
     ],
     # Choose your license
     license="MIT",