Add simple example

Author: ilikecake

examples/circuitpython_i2c_expanders_simpletest.py

@@ -2,3 +2,51 @@
 # SPDX-FileCopyrightText: Copyright (c) 2023 Pat Satyshur
 #
 # SPDX-License-Identifier: Unlicense
+
+import time
+import board
+import digitalio
+from i2c_expanders.PCAL9555 import PCAL9555
+
+# To use default I2C bus (most boards)
+i2c = board.I2C()  # uses board.SCL and board.SDA
+
+# Change this to match the address of the device.
+PCAL9555_Address = 0x20
+
+# Initialize the device and get pins
+IOEXP1_dev = PCAL9555.PCAL9555(i2c, address=PCAL9555_Address)
+pin0 = IOEXP1_dev.get_pin(0)
+pin1 = IOEXP1_dev.get_pin(1)
+pin2 = IOEXP1_dev.get_pin(2)
+pin3 = IOEXP1_dev.get_pin(3)
+
+# Pin 0 is an output with an initial value of high (true)
+pin0.switch_to_output(value=True)
+
+# Pin 1 is an output with an initial value of low (false)
+pin1.switch_to_output(value=False)
+
+# Pin 2 is an input with a pull up resistor and standard polarity
+pin2.switch_to_input(pull=digitalio.Pull.UP, invert_polarity=False)
+
+# Pin 3 is an input with a pull down resistor and inverted polarity
+pin3.switch_to_input(pull=digitalio.Pull.DOWN, invert_polarity=True)
+
+# Toggle output pins. Read value from input pins.
+while True:
+    pin0.value = False
+    pin1.value = True
+    print("pin 0: False")
+    print("pin 1: True")
+    print("pin 2: ", pin2.value)
+    print("pin 3: ", pin3.value)
+    time.sleep(1)
+
+    pin0.value = True
+    pin1.value = False
+    print("pin 0: True")
+    print("pin 1: False")
+    print("pin 2: ", pin2.value)
+    print("pin 3: ", pin3.value)
+    time.sleep(1)