Merge pull request gpiozero#441 from lurch/add_pistop_board

Add support for the Pi-Stop Traffic-light board

Author: bennuttall

docs/api_boards.rst

@@ -71,6 +71,13 @@ PI-TRAFFIC
     :inherited-members:
     :members:
 
+Pi-Stop
+=======
+
+.. autoclass:: PiStop
+    :inherited-members:
+    :members:
+
 TrafficLightsBuzzer
 ===================
 

docs/images/composite_device_hierarchy.dot

@@ -25,6 +25,7 @@ digraph classes {
     PiLiterBarGraph->LEDBarGraph;
     TrafficLights->LEDBoard;
     PiTraffic->TrafficLights;
+    PiStop->TrafficLights;
     TrafficLightsBuzzer->CompositeOutputDevice;
     FishDish->TrafficLightsBuzzer;
     TrafficHat->TrafficLightsBuzzer;

docs/images/composite_device_hierarchy.pdf

@@ -116,6 +116,7 @@
     PiLiterBarGraph,
     TrafficLights,
     PiTraffic,
+    PiStop,
     SnowPi,
     TrafficLightsBuzzer,
     FishDish,

docs/images/composite_device_hierarchy.png

@@ -753,6 +753,55 @@ def __init__(self, pwm=False, initial_value=False):
                                         pwm=pwm, initial_value=initial_value)
 
 
+class PiStop(TrafficLights):
+    """
+    Extends :class:`TrafficLights` for the `PiHardware Pi-Stop`_: a vertical
+    traffic lights board.
+
+    The following example turns on the amber LED on a Pi-Stop
+    connected to location ``A+``::
+
+        from gpiozero import PiStop
+
+        traffic = PiStop('A+')
+        traffic.amber.on()
+
+    :param str location:
+        The `location`_ on the GPIO header to which the Pi-Stop is connected.
+        Must be one of: ``A``, ``A+``, ``B``, ``B+``, ``C``, ``D``.
+
+    :param bool pwm:
+        If ``True``, construct :class:`PWMLED` instances to represent each
+        LED. If ``False`` (the default), construct regular :class:`LED`
+        instances.
+
+    :param bool initial_value:
+        If ``False`` (the default), all LEDs will be off initially. If
+        ``None``, each device will be left in whatever state the pin is found
+        in when configured for output (warning: this can be on). If ``True``,
+        the device will be switched on initially.
+
+    .. _PiHardware Pi-Stop: https://pihw.wordpress.com/meltwaters-pi-hardware-kits/pi-stop/
+    .. _location: https://github.com/PiHw/Pi-Stop/blob/master/markdown_source/markdown/Discover-PiStop.md
+    """
+    LOCATIONS = {
+        'A': (7, 8, 25),
+        'A+': (21, 20, 16),
+        'B': (10, 9, 11),
+        'B+': (13, 19, 26),
+        'C': (18, 15, 14),
+        'D': (2, 3, 4),
+    }
+
+    def __init__(self, location=None, pwm=False, initial_value=False):
+        gpios = self.LOCATIONS.get(location, None)
+        if gpios is None:
+            raise ValueError('location must be one of: %s' %
+                             ', '.join(sorted(self.LOCATIONS.keys())))
+        super(PiStop, self).__init__(*gpios,
+                                        pwm=pwm, initial_value=initial_value)
+
+
 class SnowPi(LEDBoard):
     """
     Extends :class:`LEDBoard` for the `Ryanteck SnowPi`_ board.

docs/images/composite_device_hierarchy.svg

@@ -580,6 +580,30 @@ def test_pi_traffic():
     with PiTraffic() as board:
         assert [device.pin for device in board] == pins
 
+def test_pi_stop():
+    with pytest.raises(ValueError):
+        PiStop()
+    with pytest.raises(ValueError):
+        PiStop('E')
+    pins_a = [MockPin(n) for n in (7, 8, 25)]
+    with PiStop('A') as board:
+        assert [device.pin for device in board] == pins_a
+    pins_aplus = [MockPin(n) for n in (21, 20, 16)]
+    with PiStop('A+') as board:
+        assert [device.pin for device in board] == pins_aplus
+    pins_b = [MockPin(n) for n in (10, 9, 11)]
+    with PiStop('B') as board:
+        assert [device.pin for device in board] == pins_b
+    pins_bplus = [MockPin(n) for n in (13, 19, 26)]
+    with PiStop('B+') as board:
+        assert [device.pin for device in board] == pins_bplus
+    pins_c = [MockPin(n) for n in (18, 15, 14)]
+    with PiStop('C') as board:
+        assert [device.pin for device in board] == pins_c
+    pins_d = [MockPin(n) for n in (2, 3, 4)]
+    with PiStop('D') as board:
+        assert [device.pin for device in board] == pins_d
+
 def test_snow_pi():
     pins = [MockPin(n) for n in (23, 24, 25, 17, 18, 22, 7, 8, 9)]
     with SnowPi() as board: