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examples: Add practical examples for mcp23009e driver. (#247)
* fix(mcp23009e): Remove test script from example * feat(mcp23009e): add reaction time example * feat(mcp23009e): add simon game example * feat(mcp23009e): add combination lock example * feat(mcp23009e): add dpad counter example * feat(mcp23009e): add morse code example * feat(mcp23009e): add binary counter example * feat(mcp23009e): add navigation menu example * feat(mcp23009e): add dpad piano example * docs(mcp23009e): add example to readme * feat(mcp23009e): add sleep on button example * docs(mcp23009e): add sleep on example to readme * docs(mcp23009e): fix examples errors. - Binary counter -> (GPIO1–GPIO4 / pins 0–3) - Example command with a existing file * fix(mcp23009e): More reliable interrupt in sleep_on_button interrupt capture registers to reliably detect wake button * fix(mcp23009e): replace wrong pin in dpad piano example * docs(mcp23009e): clarify GPIO naming for binary counter output pins In binary_counter example docstring * fix(lis2mdl): added menu btn to exit dpad piano example
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‎lib/mcp23009e/README.md‎

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

‎lib/mcp23009e/examples/binary_counter.py‎

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

‎lib/mcp23009e/examples/combination_lock.py‎

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

‎lib/mcp23009e/examples/dpad_counter.py‎

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

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