feat: added examples

Author: gpongelli

README.rst

@@ -65,8 +65,26 @@ Or the following command to update an existing version:
 Usage Example
 =============
 
-.. todo:: Add a quick, simple example. It and other examples should live in the
-examples folder and be included in docs/examples.rst.
+.. code-block:: python
+
+    import board
+
+    from gpio_expander import PCA9555, PCA9534
+
+    #######################
+    # 16 bit I2C expander #
+    #######################
+    _pca9555 = PCA9555(board.I2C(), 0x20)
+
+    # print input 0 bit 0 value; datasheet bit field's name has underscore in place of dot for 16 bit expander
+    print(_pca9555.I0_0)
+
+    # configure an output port and set its value
+    _pca9555.C1_3 = 0
+    _pca9555.O1_3 = 0
+
+    # print entire configuration registry
+    print(_pca9555.configuration_ports)
 
 Documentation
 =============

examples/gpio_expander_simpletest.py

@@ -1,4 +1,40 @@
+"""Simple tests."""
+
 # SPDX-FileCopyrightText: 2017 Scott Shawcroft, written for Adafruit Industries
 # SPDX-FileCopyrightText: Copyright (c) 2022 Gabriele Pongelli
 #
 # SPDX-License-Identifier: Unlicense
+
+import board
+
+from gpio_expander import PCA9534, PCA9555
+
+#######################
+# 16 bit I2C expander #
+#######################
+_pca9555 = PCA9555(board.I2C(), 0x20)
+
+# print input 0 bit 0 value; datasheet bit field's name has underscore in place of dot for 16 bit expander
+print(_pca9555.I0_0)  # pylint: disable=no-member
+
+# configure an output port and set its value
+_pca9555.C1_3 = 0
+_pca9555.O1_3 = 0
+
+# print entire configuration registry
+print(_pca9555.configuration_ports)  # pylint: disable=no-member
+
+######################
+# 8 bit I2C expander #
+######################
+_pca9534 = PCA9534(board.I2C(), 0x30)
+
+# print input 0 bit value
+print(_pca9534.I0)  # pylint: disable=no-member
+
+# configure an output port and set its value
+_pca9555.C3 = 0  # pylint: disable=invalid-name
+_pca9555.O3 = 0  # pylint: disable=invalid-name
+
+# print entire configuration registry
+print(_pca9534.configuration_ports)  # pylint: disable=no-member