Add a GPIO class to support PCA9XXX chips

Author: Pelado-Mat

Adafruit_GPIO/PCA95xx.py

@@ -0,0 +1,121 @@
+'''
+Adafruit compatible using BaseGPIO class to represent a PCA9555 IO expander
+Copyright (C) 2016 Matias Vidal
+Ported from: https://github.com/dberlin/PCA95XX
+
+# Copyright 2012 Daniel Berlin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.'''
+
+import Adafruit_GPIO as GPIO
+import Adafruit_GPIO.I2C as I2C
+
+# For the PCA 953X and 955X series, the chips with 8 GPIO's have these port numbers
+# The chips with 16 GPIO's have the first port for each type at double these numbers
+# IE The first config port is 6
+
+INPUT_PORT = 0
+OUTPUT_PORT = 1
+POLARITY_PORT = 2
+CONFIG_PORT = 3
+
+IN = GPIO.IN
+OUT = GPIO.OUT
+HIGH = GPIO.HIGH
+LOW = GPIO.LOW
+
+
+class PCA9555(GPIO.BaseGPIO):
+    """Class to represent a PCA9555  GPIO extender. Compatible
+    with the Adafruit_GPIO BaseGPIO class so it can be used as a custom GPIO
+    class for interacting with device.
+    """
+    NUM_GPIO = 16
+
+    def __init__(self, address=0x20, busnum=None, i2c=None, num_gpios=16, **kwargs):
+        address = int(address)
+        self.__name__ = "PCA955"
+        # Create I2C device.
+        i2c = i2c or I2C
+        busnum = busnum or i2c.get_default_bus()
+        self._device = i2c.get_i2c_device(address, busnum, **kwargs)
+        self.num_gpios = num_gpios
+        
+        if self.num_gpios <= 8:
+            self.iodir = self._device.readU8(CONFIG_PORT)
+            self.outputvalue = self._device.readU8(OUTPUT_PORT)
+
+        elif self.num_gpios > 8 and self.num_gpios <= 16:
+            self.iodir = self._device.readU16(CONFIG_PORT<< 1)
+            self.outputvalue = self._device.readU16(OUTPUT_PORT << 1)
+
+    def _changebit(self, bitmap, bit, value):
+        assert value == 1 or value == 0, "Value is %s must be 1 or 0" % value
+        if value == 0:
+            return bitmap & ~(1 << bit)
+        elif value == 1:
+            return bitmap | (1 << bit)
+
+    # Change the value of bit PIN on port PORT to VALUE.  If the
+    # current pin state for the port is passed in as PORTSTATE, we
+    # will avoid doing a read to get it.  The port pin state must be
+    # complete if passed in (IE it should not just be the value of the
+    # single pin we are trying to change)
+    def _readandchangepin(self, port, pin, value, portstate = None):
+        assert pin >= 0 and pin < self.num_gpios, "Pin number %s is invalid, only 0-%s are valid" % (pin, self.num_gpios)
+        if not portstate:
+          if self.num_gpios <= 8:
+             portstate = self._device.readU8(port)
+          elif self.num_gpios > 8 and self.num_gpios <= 16:
+             portstate = self._device.readU16(port << 1)
+        newstate = self._changebit(portstate, pin, value)
+        if self.num_gpios <= 8:
+            self._device.write8(port, newstate)
+        else:
+            self._device.write16(port << 1, newstate)
+        return newstate
+
+    # Polarity inversion
+    def polarity(self, pin, value):
+        return self._readandchangepin(POLARITY_PORT, pin, value)
+
+    # Pin direction
+    def config(self, pin, mode):
+        self.iodir = self._readandchangepin(CONFIG_PORT, pin, mode, self.iodir)
+        return self.iodir
+
+    def output(self, pin, value):
+        assert self.iodir & (1 << pin) == 0, "Pin %s not set to output" % pin
+        self.outputvalue = self._readandchangepin(OUTPUT_PORT, pin, value, self.outputvalue)
+        return self.outputvalue
+
+    def input(self, pin):
+        assert self.iodir & (1 << pin) != 0, "Pin %s not set to input" % pin
+        if self.num_gpios <= 8:
+            value = self._device.readU8(INPUT_PORT)
+        elif self.num_gpios > 8 and self.num_gpios <= 16:
+            value = self._device.readU16(INPUT_PORT << 1)
+        return value & (1 << pin)
+
+    def setup(self, pin, mode):
+        self.config(pin, mode)
+
+    def cleanup(self, pin=None):
+        # nothing to cleanup
+        pass