Merge pull request #35 from shadowclaw/master

Adding support for defining input pin polarity

adafruit_mcp230xx/digital_inout.py

@@ -60,13 +60,14 @@ def switch_to_output(self, value=False, **kwargs):
         self.direction = digitalio.Direction.OUTPUT
         self.value = value
 
-    def switch_to_input(self, pull=None, **kwargs):
+    def switch_to_input(self, pull=None, invert_polarity=False, **kwargs):
         """Switch the pin state to a digital input with the provided starting
-        pull-up resistor state (optional, no pull-up by default).  Note that
+        pull-up resistor state (optional, no pull-up by default) and input polarity.  Note that
         pull-down resistors are NOT supported!
         """
         self.direction = digitalio.Direction.INPUT
         self.pull = pull
+        self.invert_polarity = invert_polarity
 
     # pylint: enable=unused-argument
 
@@ -131,3 +132,19 @@ def pull(self, val):
         except AttributeError as error:
             # MCP23016 doesn't have a `gppu` register.
             raise ValueError("Pull-up/pull-down resistors not supported.") from error
+
+    @property
+    def invert_polarity(self):
+        """The polarity of the pin, either True for an Inverted or
+        False for an normal.
+        """
+        if _get_bit(self._mcp.ipol, self._pin):
+            return True
+        return False
+
+    @invert_polarity.setter
+    def invert_polarity(self, val):
+        if val:
+            self._mcp.ipol = _enable_bit(self._mcp.ipol, self._pin)
+        else:
+            self._mcp.ipol = _clear_bit(self._mcp.ipol, self._pin)

adafruit_mcp230xx/mcp23017.py

@@ -3,6 +3,8 @@
 #
 # SPDX-License-Identifier: MIT
 
+# pylint: disable=too-many-public-methods
+
 """
 `mcp23017`
 ====================================================
@@ -23,6 +25,7 @@
 _MCP23017_IODIRA = const(0x00)
 _MCP23017_IODIRB = const(0x01)
 _MCP23017_IPOLA = const(0x02)
+_MCP23017_IPOLB = const(0x03)
 _MCP23017_GPINTENA = const(0x04)
 _MCP23017_DEFVALA = const(0x06)
 _MCP23017_INTCONA = const(0x08)
@@ -162,6 +165,42 @@ def get_pin(self, pin):
         assert 0 <= pin <= 15
         return DigitalInOut(pin, self)
 
+    @property
+    def ipol(self):
+        """The raw IPOL output register.  Each bit represents the
+        polarity value of the associated pin (0 = normal, 1 = inverted), assuming that
+        pin has been configured as an input previously.
+        """
+        return self._read_u16le(_MCP23017_IPOLA)
+
+    @ipol.setter
+    def ipol(self, val):
+        self._write_u16le(_MCP23017_IPOLA, val)
+
+    @property
+    def ipola(self):
+        """The raw IPOL A output register.  Each bit represents the
+        polarity value of the associated pin (0 = normal, 1 = inverted), assuming that
+        pin has been configured as an input previously.
+        """
+        return self._read_u8(_MCP23017_IPOLA)
+
+    @ipola.setter
+    def ipola(self, val):
+        self._write_u8(_MCP23017_IPOLA, val)
+
+    @property
+    def ipolb(self):
+        """The raw IPOL B output register.  Each bit represents the
+        polarity value of the associated pin (0 = normal, 1 = inverted), assuming that
+        pin has been configured as an input previously.
+        """
+        return self._read_u8(_MCP23017_IPOLB)
+
+    @ipolb.setter
+    def ipolb(self, val):
+        self._write_u8(_MCP23017_IPOLB, val)
+
     @property
     def interrupt_configuration(self):
         """The raw INTCON interrupt control register. The INTCON register