examples: Add practical examples for mcp23009e driver.

lib/mcp23009e/README.md

@@ -194,21 +194,24 @@ Toggles the reset pin to perform a hardware reset.
 
 ## Examples
 
-The library includes several examples:
-
-* `buttons.py` - Simple button reading with polling
-* `i2c_scan.py` - Scan I2C buses for connected devices
-* `test_basic.py` - Basic driver functionality tests
-* `test_interrupts.py` - Interrupt system demonstration
-* `test_led_simple.py` - Basic active-low LED control example
-* `test_output_active_low.py` - Active-low output tests with inverted logic
-* `test_output.py` - GPIO output tests using low-level and Pin APIs
-* `test_pin.py` - MCP23009Pin class usage examples
-* `test_pin_irq.py` - Pin-compatible interrupt examples
-
+The library includes several practical examples:
+
+| Example                | Description |
+|-----------------------|------------|
+| `buttons.py`          | Simple D-PAD button reading using polling (no interrupts) |
+| `i2c_scan.py`         | Scan the I2C bus to detect connected devices |
+| `reaction_timer.py`   | Reaction time game using D-PAD buttons and interrupts (best of 5 rounds) |
+| `simon.py`            | Simon Says memory game using the D-PAD |
+| `combination_lock.py` | Digital lock using a secret D-PAD sequence |
+| `dpad_counter.py`     | Simple state machine: increment/decrement/reset/print using D-PAD |
+| `morse_code.py`       | Morse code input using button press duration (dot/dash detection) |
+| `binary_counter.py`   | 4-bit binary counter displayed on GPIO outputs (GPIO1–GPIO4 / pins 0–3) |  
+| `dpad_piano.py`       | Play musical notes with the D-PAD and buzzer (multi-press = higher octave) |
+| `menu_navigation.py`  | Minimal centered UI for navigating a menu on the SSD1327 OLED display |
+| `sleep_on_button.py`  | Low-power example: wake the board from sleep using MCP23009E interrupts |
 
 ### How to run 
 
 ```python
-mpremote mount lib/mcp23009e run lib/mcp23009e/examples/test_basic.py
+mpremote mount lib/mcp23009e run lib/mcp23009e/examples/buttons.py
 ```

lib/mcp23009e/examples/binary_counter.py

@@ -0,0 +1,87 @@
+"""
+Binary counter using D-PAD inputs and MCP23009E GPIO outputs.
+
+UP    -> increment
+DOWN  -> decrement
+LEFT  -> reset
+RIGHT -> print current value
+
+The value is displayed on GPIO1..GPIO4 (expander pins 0..3)
+as a 4-bit binary number.
+"""
+
+from time import sleep_ms
+
+from machine import I2C, Pin
+from mcp23009e import MCP23009E
+from mcp23009e.const import *
+
+bus = I2C(1)
+reset = Pin("RST_EXPANDER", Pin.OUT)
+
+mcp = MCP23009E(bus, address=MCP23009_I2C_ADDR, reset_pin=reset)
+
+BUTTONS = {
+    MCP23009_BTN_UP: "UP",
+    MCP23009_BTN_DOWN: "DOWN",
+    MCP23009_BTN_LEFT: "LEFT",
+    MCP23009_BTN_RIGHT: "RIGHT",
+}
+
+OUTPUT_PINS = [MCP23009_GPIO1, MCP23009_GPIO2, MCP23009_GPIO3, MCP23009_GPIO4]
+
+
+def wait_all_released():
+    while True:
+        if all(mcp.get_level(pin_number) == MCP23009_LOGIC_HIGH for pin_number in BUTTONS):
+            return
+        sleep_ms(20)
+
+
+def wait_for_button():
+    wait_all_released()
+    while True:
+        for pin_number, name in BUTTONS.items():
+            if mcp.get_level(pin_number) == MCP23009_LOGIC_LOW:
+                while mcp.get_level(pin_number) == MCP23009_LOGIC_LOW:
+                    sleep_ms(20)
+                return name
+        sleep_ms(20)
+
+
+def update_outputs(value):
+    for bit_index, pin_number in enumerate(OUTPUT_PINS):
+        bit_value = (value >> bit_index) & 0x01
+        mcp.set_level(pin_number, bit_value)
+
+
+for pin_number in BUTTONS:
+    mcp.setup(pin_number, MCP23009_DIR_INPUT, pullup=MCP23009_PULLUP)
+
+for pin_number in OUTPUT_PINS:
+    mcp.setup(pin_number, MCP23009_DIR_OUTPUT)
+    mcp.set_level(pin_number, MCP23009_LOGIC_LOW)
+
+counter = 0
+update_outputs(counter)
+
+print("=================================")
+print("Binary Counter")
+print("=================================\n")
+print("Displaying the 4-bit value on GP0..GP3")
+print("UP=+1  DOWN=-1  LEFT=reset  RIGHT=print\n")
+
+while True:
+    button = wait_for_button()
+
+    if button == "UP":
+        counter = (counter + 1) & 0x0F
+    elif button == "DOWN":
+        counter = (counter - 1) & 0x0F
+    elif button == "LEFT":
+        counter = 0
+    elif button == "RIGHT":
+        pass
+
+    update_outputs(counter)
+    print("Value:", counter, " Binary:", "{:04b}".format(counter))

lib/mcp23009e/examples/combination_lock.py

@@ -0,0 +1,73 @@
+"""
+Digital combination lock using the MCP23009E D-PAD.
+
+Enter the secret button sequence to unlock.
+A wrong input resets the attempt.
+"""
+
+from time import sleep_ms
+
+from machine import I2C, Pin
+from mcp23009e import MCP23009E
+from mcp23009e.const import *
+
+bus = I2C(1)
+reset = Pin("RST_EXPANDER", Pin.OUT)
+
+mcp = MCP23009E(bus, address=MCP23009_I2C_ADDR, reset_pin=reset)
+
+BUTTONS = {
+    MCP23009_BTN_UP: "UP",
+    MCP23009_BTN_DOWN: "DOWN",
+    MCP23009_BTN_LEFT: "LEFT",
+    MCP23009_BTN_RIGHT: "RIGHT",
+}
+
+SECRET = ["UP", "UP", "DOWN", "LEFT", "RIGHT"]
+
+
+def wait_all_released():
+    while True:
+        if all(mcp.get_level(pin_number) == MCP23009_LOGIC_HIGH for pin_number in BUTTONS):
+            return
+        sleep_ms(20)
+
+
+def wait_for_button():
+    wait_all_released()
+    while True:
+        for pin_number, name in BUTTONS.items():
+            if mcp.get_level(pin_number) == MCP23009_LOGIC_LOW:
+                while mcp.get_level(pin_number) == MCP23009_LOGIC_LOW:
+                    sleep_ms(20)
+                return name
+        sleep_ms(20)
+
+
+for pin_number in BUTTONS:
+    mcp.setup(pin_number, MCP23009_DIR_INPUT, pullup=MCP23009_PULLUP)
+
+print("=================================")
+print("Combination Lock")
+print("=================================\n")
+print("Enter the secret D-PAD sequence.\n")
+
+entered = []
+
+while True:
+    button = wait_for_button()
+    entered.append(button)
+
+    print("Input:", "-".join(entered))
+
+    expected_prefix = SECRET[: len(entered)]
+    if entered != expected_prefix:
+        print("WRONG")
+        entered = []
+        print()
+        continue
+
+    if len(entered) == len(SECRET):
+        print("UNLOCKED")
+        entered = []
+        print()

lib/mcp23009e/examples/dpad_counter.py

@@ -0,0 +1,70 @@
+"""
+Simple D-PAD counter.
+
+UP    -> increment
+DOWN  -> decrement
+LEFT  -> reset
+RIGHT -> print current value
+"""
+
+from time import sleep_ms
+
+from machine import I2C, Pin
+from mcp23009e import MCP23009E
+from mcp23009e.const import *
+
+bus = I2C(1)
+reset = Pin("RST_EXPANDER", Pin.OUT)
+
+mcp = MCP23009E(bus, address=MCP23009_I2C_ADDR, reset_pin=reset)
+
+BUTTONS = {
+    MCP23009_BTN_UP: "UP",
+    MCP23009_BTN_DOWN: "DOWN",
+    MCP23009_BTN_LEFT: "LEFT",
+    MCP23009_BTN_RIGHT: "RIGHT",
+}
+
+
+def wait_all_released():
+    while True:
+        if all(mcp.get_level(pin_number) == MCP23009_LOGIC_HIGH for pin_number in BUTTONS):
+            return
+        sleep_ms(20)
+
+
+def wait_for_button():
+    wait_all_released()
+    while True:
+        for pin_number, name in BUTTONS.items():
+            if mcp.get_level(pin_number) == MCP23009_LOGIC_LOW:
+                while mcp.get_level(pin_number) == MCP23009_LOGIC_LOW:
+                    sleep_ms(20)
+                return name
+        sleep_ms(20)
+
+
+for pin_number in BUTTONS:
+    mcp.setup(pin_number, MCP23009_DIR_INPUT, pullup=MCP23009_PULLUP)
+
+value = 0
+
+print("=================================")
+print("D-PAD Counter")
+print("=================================\n")
+print("UP=+1  DOWN=-1  LEFT=reset  RIGHT=print\n")
+
+while True:
+    button = wait_for_button()
+
+    if button == "UP":
+        value += 1
+        print("Increment ->", value)
+    elif button == "DOWN":
+        value -= 1
+        print("Decrement ->", value)
+    elif button == "LEFT":
+        value = 0
+        print("Reset ->", value)
+    elif button == "RIGHT":
+        print("Current value ->", value)