Merge pull request #93 from fvlima/explicity-force-selection

Add force_selection parameter to DC class

docs/user-guide/python-scripts.md

@@ -16,6 +16,14 @@ In this example, the GPIO pin numbers will be the same as listed in [Hardware Se
 motor1 = l293d.DC(22, 18, 16)
 ```
 
+In some cases, it may be necessary to use some pins that aren't considered valid, but we can force it 
+by expliciting the `force_selection` parameter as `True` in DC class initialization (by default, this
+parameter is `False`).
+
+```python
+motor1 = l293d.DC(19, 21, 23, force_selection=True)
+```
+
 In this case, 'motor1' is what we're calling the DC motor object. You can call it whatever you want,
 for example `wheel_motor`, `london_eye` or `spinny_thing`.
 

l293d/driver.py

@@ -52,7 +52,7 @@ class DC(object):
     motor_pins[2] is pinC is L293D pin7 or pin15 : Clockwise positive
     """
 
-    def __init__(self, pin_a=0, pin_b=0, pin_c=0):
+    def __init__(self, pin_a=0, pin_b=0, pin_c=0, force_selection=False):
         # Assign parameters to list
         self.motor_pins = [0 for x in range(3)]
         self.motor_pins[0] = pin_a
@@ -66,7 +66,7 @@ def __init__(self, pin_a=0, pin_b=0, pin_c=0):
         self.reversed = False
 
         # Check pins are valid
-        if pins_are_valid(self.motor_pins):
+        if pins_are_valid(self.motor_pins, force_selection):
             self.exists = True
         # Append to global list of pins in use
         for pin in self.motor_pins:

tests/test_l293d.py

@@ -23,6 +23,19 @@ def test_import(self):
         self.assertTrue(True)
         reload(d.driver)  # Revert changes
 
+    def test_create_motor_with_force_selection(self):
+        """
+        Test DC class instance creation with explicity
+        force_selection parameter
+        """
+        import l293d as d
+        cases = (([33, 36, 37], False), ([19, 21, 23], True))
+        for pins, force_selection in cases:
+            motor = d.DC(*pins, force_selection=force_selection)
+            self.assertEqual(d.pins_in_use, pins)
+            motor.remove()
+        reload(d.driver)
+
     def test_pins_string_list(self):
         """
         Test that the list of pins is returned correctly