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Add interrupt handling examples
Add three comprehensive examples demonstrating interrupt functionality: 1. InterruptBasic: - Simple single-button interrupt handling - Demonstrates FALLING (press) and RISING (release) modes - Shows proper ISR implementation with debouncing - Uses SimpleCallback for button events 2. InterruptMultipleButtons: - Handle interrupts from all D-PAD buttons simultaneously - Demonstrates CHANGE mode with level parameter - Per-button callbacks with event tracking - Press statistics for all buttons 3. InterruptWithPin: - Uses Pin-compatible API with interrupts - Demonstrates attachInterrupt/detachInterrupt - LED control triggered by button interrupts - Long press detection (>2s) for special actions All examples include: - STEAMI board I2C configuration - Proper debouncing (50ms) - Detailed comments and usage instructions - Error handling checks - Status reporting Updated README with interrupt examples section.
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‎README.md‎

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The library includes several examples:
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### Basic Examples
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- **BasicUsage** - Read D-PAD buttons and print states
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- **LED_ActiveLow** - Control LEDs in active-low configuration with effects
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- **ErrorHandling** - Demonstrates I2C error detection and handling
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### Interrupt Examples
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- **InterruptBasic** - Simple interrupt handling with one button (FALLING/RISING)
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- **InterruptMultipleButtons** - Handle interrupts from multiple buttons (CHANGE mode)
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- **InterruptWithPin** - Use Pin API with interrupts and LED control
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## Hardware Considerations
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### I2C Address

‎examples/InterruptBasic/InterruptBasic.ino‎

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/**
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* Basic Interrupt Example for MCP23009E Library
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*
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* This example demonstrates how to use hardware interrupts with the MCP23009E.
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* When a button is pressed, an interrupt is triggered and handled automatically.
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*
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* Hardware Setup:
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* - MCP23009E connected via I2C
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* - Button on GPIO 7 (with pull-up enabled)
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* - MCP23009E INT pin connected to microcontroller GPIO (INT_EXPANDER)
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*
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* Interrupt modes:
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* - FALLING: Triggered when button is pressed (HIGH to LOW)
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* - RISING: Triggered when button is released (LOW to HIGH)
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* - CHANGE: Triggered on both press and release
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*
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* Note: The interrupt pin configuration and ISR attachment are now handled
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* automatically by the library when you pass the interruptPin to begin().
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*/
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#include <Wire.h>
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#include <MCP23009E.h>
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// Create MCP23009E instance
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MCP23009E mcp(Wire, MCP23009_I2C_ADDR);
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// Reset pin (adjust for your board)
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const int RESET_PIN = RST_EXPANDER; // Set to your reset pin number, or -1 if none
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const int INTERRUPT_PIN = INT_EXPANDER; // Microcontroller pin connected to MCP23009E INT
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// Button configuration
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const int BUTTON_PIN = MCP23009_BTN_UP; // Use D-PAD UP button (GPIO 7)
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// Volatile variables for interrupt handling
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volatile bool buttonPressed = false;
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volatile bool buttonReleased = false;
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// Callback for button press (falling edge)
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void onButtonPress() {
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buttonPressed = true;
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}
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// Callback for button release (rising edge)
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void onButtonRelease() {
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buttonReleased = true;
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}
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void setup() {
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Serial.begin(115200);
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while (!Serial) delay(10);
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Serial.println("Initializing I2C...");
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Wire.setSDA(I2C_INT_SDA);
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Wire.setSCL(I2C_INT_SCL);
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Wire.begin();
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Serial.println("================================");
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Serial.println("MCP23009E Interrupt Basic Example");
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Serial.println("================================\n");
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// Initialize MCP23009E
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mcp.begin(RESET_PIN, INTERRUPT_PIN);
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// Configure button as input with pull-up
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Serial.println("Configuring button with interrupts...");
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mcp.setup(BUTTON_PIN, MCP23009_DIR_INPUT, MCP23009_PULLUP);
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// Configure interrupts on the MCP23009E
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// Note: The interrupt pin and ISR are automatically configured by begin()
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mcp.interruptOnFalling(BUTTON_PIN, onButtonPress);
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mcp.interruptOnRaising(BUTTON_PIN, onButtonRelease);
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Serial.println("✓ Interrupt configuration complete");
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Serial.println("\nPress the UP button to trigger interrupts...\n");
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Serial.println("(Button should be connected with pull-up)");
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Serial.println("Press = FALLING interrupt");
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Serial.println("Release = RISING interrupt\n");
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}
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uint32_t pressCount = 0;
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uint32_t releaseCount = 0;
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void loop() {
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// Handle button press events in main loop (not in ISR)
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if (buttonPressed) {
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buttonPressed = false;
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pressCount++;
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Serial.print("✓ Button PRESSED (count: ");
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Serial.print(pressCount);
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Serial.println(")");
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}
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// Handle button release events in main loop (not in ISR)
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if (buttonReleased) {
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buttonReleased = false;
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releaseCount++;
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Serial.print("✓ Button RELEASED (count: ");
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Serial.print(releaseCount);
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Serial.println(")");
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}
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// Print status every 5 seconds
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static uint32_t lastStatusTime = 0;
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if (millis() - lastStatusTime > 5000) {
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lastStatusTime = millis();
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Serial.println("\n--- Status ---");
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Serial.print("Total presses: ");
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Serial.println(pressCount);
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Serial.print("Total releases: ");
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Serial.println(releaseCount);
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Serial.println("Waiting for interrupts...\n");
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}
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// Small delay to avoid excessive CPU usage
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delay(10);
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}

‎examples/InterruptMultipleButtons/InterruptMultipleButtons.ino‎

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/**
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* Multiple Buttons Interrupt Example for MCP23009E Library
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*
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* This example demonstrates handling interrupts from multiple buttons (D-PAD).
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* Each button can trigger an interrupt and the handler identifies which button
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* caused the interrupt and its state (pressed/released).
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*
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* Hardware Setup:
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* - MCP23009E connected via I2C
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* - D-PAD buttons on GPIO 4, 5, 6, 7 (with pull-ups enabled)
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* - MCP23009E INT pin connected to microcontroller GPIO (INT_EXPANDER)
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*
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* D-PAD Button Mapping:
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* - GPIO 7: UP
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* - GPIO 5: DOWN
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* - GPIO 6: LEFT
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* - GPIO 4: RIGHT
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*
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* Note: The interrupt pin configuration and ISR attachment are now handled
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* automatically by the library when you pass the interruptPin to begin().
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*/
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#include <Wire.h>
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#include <MCP23009E.h>
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// Create MCP23009E instance
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MCP23009E mcp(Wire, MCP23009_I2C_ADDR);
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// Reset pin (adjust for your board)
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const int RESET_PIN = RST_EXPANDER;
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const int INTERRUPT_PIN = INT_EXPANDER;
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// Button states
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struct ButtonState {
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bool changed;
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uint8_t level;
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uint32_t pressCount;
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};
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volatile ButtonState upButton = {false, HIGH, 0};
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volatile ButtonState downButton = {false, HIGH, 0};
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volatile ButtonState leftButton = {false, HIGH, 0};
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volatile ButtonState rightButton = {false, HIGH, 0};
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// Individual button callbacks using CHANGE mode
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void onUpButtonChange(uint8_t level) {
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upButton.changed = true;
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upButton.level = level;
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if (level == LOW) upButton.pressCount++;
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}
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void onDownButtonChange(uint8_t level) {
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downButton.changed = true;
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downButton.level = level;
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if (level == LOW) downButton.pressCount++;
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}
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void onLeftButtonChange(uint8_t level) {
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leftButton.changed = true;
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leftButton.level = level;
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if (level == LOW) leftButton.pressCount++;
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}
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void onRightButtonChange(uint8_t level) {
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rightButton.changed = true;
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rightButton.level = level;
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if (level == LOW) rightButton.pressCount++;
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}
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void setup() {
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Serial.begin(115200);
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while (!Serial) delay(10);
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Serial.println("Initializing I2C...");
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Wire.setSDA(I2C_INT_SDA);
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Wire.setSCL(I2C_INT_SCL);
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Wire.begin();
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Serial.println("========================================");
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Serial.println("MCP23009E Multiple Buttons Interrupt Example");
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Serial.println("========================================\n");
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// Initialize MCP23009E
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mcp.begin(RESET_PIN, INTERRUPT_PIN);
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// Configure all D-PAD buttons with pull-ups
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Serial.println("Configuring D-PAD buttons with interrupts...");
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mcp.setup(MCP23009_BTN_UP, MCP23009_DIR_INPUT, MCP23009_PULLUP);
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mcp.setup(MCP23009_BTN_DOWN, MCP23009_DIR_INPUT, MCP23009_PULLUP);
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mcp.setup(MCP23009_BTN_LEFT, MCP23009_DIR_INPUT, MCP23009_PULLUP);
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mcp.setup(MCP23009_BTN_RIGHT, MCP23009_DIR_INPUT, MCP23009_PULLUP);
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// Configure interrupts for all buttons (CHANGE mode with level callback)
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// Note: The interrupt pin and ISR are automatically configured by begin()
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mcp.interruptOnChange(MCP23009_BTN_UP, onUpButtonChange);
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mcp.interruptOnChange(MCP23009_BTN_DOWN, onDownButtonChange);
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mcp.interruptOnChange(MCP23009_BTN_LEFT, onLeftButtonChange);
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mcp.interruptOnChange(MCP23009_BTN_RIGHT, onRightButtonChange);
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Serial.println("✓ All interrupts configured");
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Serial.println("\nPress any D-PAD button to see interrupt handling...");
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Serial.println("(Buttons: UP, DOWN, LEFT, RIGHT)\n");
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}
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void printButtonEvent(const char* buttonName, const ButtonState& button) {
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if (button.changed) {
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Serial.print("► ");
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Serial.print(buttonName);
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Serial.print(": ");
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Serial.print(button.level ? "RELEASED" : "PRESSED");
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Serial.print(" (total presses: ");
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Serial.print(button.pressCount);
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Serial.println(")");
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}
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}
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void loop() {
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// Check and handle all button events
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bool anyChange = false;
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if (upButton.changed) {
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printButtonEvent("UP ", upButton);
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upButton.changed = false;
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anyChange = true;
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}
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if (downButton.changed) {
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printButtonEvent("DOWN ", downButton);
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downButton.changed = false;
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anyChange = true;
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}
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if (leftButton.changed) {
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printButtonEvent("LEFT ", leftButton);
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leftButton.changed = false;
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anyChange = true;
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}
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if (rightButton.changed) {
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printButtonEvent("RIGHT", rightButton);
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rightButton.changed = false;
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anyChange = true;
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}
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// Add a blank line after processing all changes
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if (anyChange) {
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Serial.println();
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}
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// Print statistics every 10 seconds
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static uint32_t lastStatsTime = 0;
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if (millis() - lastStatsTime > 10000) {
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lastStatsTime = millis();
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Serial.println("--- Button Press Statistics ---");
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Serial.print("UP: ");
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Serial.print(upButton.pressCount);
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Serial.print(" | DOWN: ");
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Serial.print(downButton.pressCount);
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Serial.print(" | LEFT: ");
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Serial.print(leftButton.pressCount);
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Serial.print(" | RIGHT: ");
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Serial.println(rightButton.pressCount);
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Serial.println("-------------------------------\n");
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}
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// Small delay
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delay(10);
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}

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