Add support for the old, deprecated MCP23016 expander, too.

The main difference with the 017 is fewer features and no ability to r/w
all 16 I/O atomically.

Author: Flameeyes

adafruit_mcp230xx/mcp23016.py

@@ -0,0 +1,104 @@
+# SPDX-FileCopyrightText: 2017 Tony DiCola for Adafruit Industries
+# SPDX-FileCopyrightText: 2019 Carter Nelson
+# SPDX-FileCopyrightText: 2020 Facebook Inc.
+#
+# SPDX-License-Identifier: MIT
+
+"""
+`mcp23016`
+====================================================
+
+CircuitPython module for the MCP23016 I2C I/O extenders.
+
+* Author(s): Diego Elio Pettenò (based on mcp23017.py)
+"""
+
+from micropython import const
+from .mcp230xx import MCP230XX
+
+__version__ = "0.0.0-auto.0"
+__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_MCP230xx.git"
+
+# pylint: disable=bad-whitespace
+_MCP23016_ADDRESS = const(0x20)
+_MCP23016_GPIO0 = const(0x00)
+_MCP23016_GPIO1 = const(0x01)
+_MCP23016_OLAT0 = const(0x02)
+_MCP23016_OLAT1 = const(0x03)
+_MCP23016_IPOL0 = const(0x04)
+_MCP23016_IPOL1 = const(0x05)
+_MCP23016_IODIR0 = const(0x06)
+_MCP23016_IODIR1 = const(0x07)
+_MCP23016_INTCAP0 = const(0x08)
+_MCP23016_INTCAP1 = const(0x09)
+_MCP23016_IOCON0 = const(0x0A)
+_MCP23016_IOCON1 = const(0x0B)
+
+
+class MCP23016(MCP230XX):
+    """Supports MCP23016 instance on specified I2C bus and optionally
+    at the specified I2C address.
+    """
+
+    def __init__(self, i2c, address=_MCP23016_ADDRESS):
+        super().__init__(i2c, address)
+
+        # Reset to all inputs and no inverted polarity.
+        self.iodir0 = 0xFF
+        self.iodir1 = 0xFF
+        self._write_u8(_MCP23016_IPOL0, 0x00)
+        self._write_u8(_MCP23016_IPOL1, 0x00)
+
+    @property
+    def iodir0(self):
+        """The raw IODIR0 direction register.  Each bit represents
+        direction of a pin, either 1 for an input or 0 for an output mode.
+        """
+        return self._read_u8(_MCP23016_IODIR0)
+
+    @iodir0.setter
+    def iodir0(self, val):
+        self._write_u8(_MCP23016_IODIR0, val)
+
+    @property
+    def iodir1(self):
+        """The raw IODIR0 direction register.  Each bit represents
+        direction of a pin, either 1 for an input or 0 for an output mode.
+        """
+        return self._read_u8(_MCP23016_IODIR1)
+
+    @iodir1.setter
+    def iodir1(self, val):
+        self._write_u8(_MCP23016_IODIR1, val)
+
+    @property
+    def gpio0(self):
+        """The raw GPIO 0 output register.  Each bit represents the
+        output value of the associated pin (0 = low, 1 = high), assuming that
+        pin has been configured as an output previously.
+        """
+        return self._read_u8(_MCP23016_GPIO0)
+
+    @gpio0.setter
+    def gpio0(self, val):
+        self._write_u8(_MCP23016_GPIO0, val)
+
+    @property
+    def gpio1(self):
+        """The raw GPIO 1 output register.  Each bit represents the
+        output value of the associated pin (0 = low, 1 = high), assuming that
+        pin has been configured as an output previously.
+        """
+        return self._read_u8(_MCP23016_GPIO1)
+
+    @gpio1.setter
+    def gpio1(self, val):
+        self._write_u8(_MCP23016_GPIO1, val)
+
+    def clear_int0(self):
+        """Clears port 0 interrupts."""
+        self._read_u8(_MCP23016_INTCAP0)
+
+    def clear_int1(self):
+        """Clears port 1 interrupts."""
+        self._read_u8(_MCP23016_INTCAP1)