Implement Pusbutton lpmode.

Author: peterhinch

DRIVERS.md

@@ -101,9 +101,10 @@ implementation.
 click or long press events; where the **function** is a coroutine it will be
 scheduled for execution and will run asynchronously.
 
-Constructor argument (mandatory):
+Constructor arguments:
 
- 1. `pin` The initialised Pin instance.
+ 1. `pin` Mandatory. The initialised Pin instance.
+ 2. `lpmode` Default `False`. See below.
 
 Methods:
 
@@ -147,6 +148,18 @@ loop = asyncio.get_event_loop()
 loop.run_until_complete(my_app())  # Run main application code
 ```
 
+The `lpmode` constructor argument modifies the behaviour of `press_func` in the
+event that a `long_func` is specified.
+
+If `lpmode` is `False`, if a button press occurs `press_func` runs immediately;
+`long_func` runs if the button is still pressed when the timeout has elapsed.
+If `lpmode` is `True`, `press_func` is delayed until button release. If, at the
+time of release, `long_func` has run, `press_func` will be suppressed.
+
+The default provides for low latency but a long button press will trigger
+`press_func` and `long_func`. `lpmode` = `True` prevents `press_func` from
+running.
+
 ## 3.3 Delay_ms class
 
 This implements the software equivalent of a retriggerable monostable or a

astests.py

@@ -60,15 +60,16 @@ def test_swcb():
     loop.run_until_complete(killer())
 
 # Test for the Pushbutton class (coroutines)
-def test_btn():
+# Pass True to test lpmode
+def test_btn(lpmode=False):
     print('Test of pushbutton scheduling coroutines.')
     print(helptext)
     pin = Pin('X1', Pin.IN, Pin.PULL_UP)
     red = LED(1)
     green = LED(2)
     yellow = LED(3)
     blue = LED(4)
-    pb = Pushbutton(pin)
+    pb = Pushbutton(pin, lpmode)
     pb.press_func(pulse, (red, 1000))
     pb.release_func(pulse, (green, 1000))
     pb.double_func(pulse, (yellow, 1000))

aswitch.py

@@ -118,8 +118,10 @@ class Pushbutton(object):
     debounce_ms = 50
     long_press_ms = 1000
     double_click_ms = 400
-    def __init__(self, pin):
+    def __init__(self, pin, lpmode=False):
         self.pin = pin # Initialise for input
+        self._lpmode = lpmode
+        self._press_pend = False
         self._true_func = False
         self._false_func = False
         self._double_func = False
@@ -176,13 +178,19 @@ async def buttoncheck(self):
                             # First click: start doubleclick timer
                             doubledelay.trigger(Pushbutton.double_click_ms)
                     if self._true_func:
-                        launch(self._true_func, self._true_args)
+                        if self._long_func and self._lpmode:
+                            self._press_pend = True  # Delay launch until release
+                        else:
+                            launch(self._true_func, self._true_args)
                 else:
                     # Button release
-                    if self._long_func and longdelay.running():
+                    if longdelay.running():
                         # Avoid interpreting a second click as a long push
                         longdelay.stop()
+                        if self._press_pend:
+                            launch(self._true_func, self._true_args)
                     if self._false_func:
                         launch(self._false_func, self._false_args)
+                    self._press_pend = False
             # Ignore state changes until switch has settled
             await asyncio.sleep_ms(Pushbutton.debounce_ms)