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// NOTE: This is a simple example that only reads the INTA or INTB pin
//       state. No actual interrupts are used on the host microcontroller.
//       MCP23XXX supports the following interrupt modes:
//           * CHANGE - interrupt occurs if pin changes to opposite state
//           * LOW - interrupt occurs while pin state is LOW
//           * HIGH - interrupt occurs while pin state is HIGH

// ok to include only the one needed
// both included here to make things simple for example
#include <Adafruit_MCP23X08.h>
#include <Adafruit_MCP23X17.h>

#define BUTTON_PIN 1   // MCP23XXX pin used for interrupt

#define INT_PIN 7      // microcontroller pin attached to INTA/B

// only used for SPI
#define CS_PIN 6

// uncomment appropriate line
Adafruit_MCP23X08 mcp;
//Adafruit_MCP23X17 mcp;

void setup() {
  Serial.begin(9600);
  //while (!Serial);
  Serial.println("MCP23xxx Interrupt Test!");

  // uncomment appropriate mcp.begin
  if (!mcp.begin_I2C()) {
  //if (!mcp.begin_SPI(CS_PIN)) {
    Serial.println("Error.");
    while (1);
  }

  // configure MCU pin that will read INTA/B state
  pinMode(INT_PIN, INPUT);

  // OPTIONAL - call this to override defaults
  // mirror INTA/B so only one wire required
  // active drive so INTA/B will not be floating
  // INTA/B will be signaled with a LOW
  mcp.setupInterrupts(true, false, LOW);

  // configure button pin for input with pull up
  mcp.pinMode(BUTTON_PIN, INPUT_PULLUP);

  // enable interrupt on button_pin
  mcp.setupInterruptPin(BUTTON_PIN, LOW);

  Serial.println("Looping...");
}

void loop() {
  if (!digitalRead(INT_PIN)) {
    Serial.print("Interrupt detected on pin: ");
    Serial.println(mcp.getLastInterruptPin());
    Serial.print("Pin states at time of interrupt: 0b");
    Serial.println(mcp.getCapturedInterrupt(), 2);
    delay(250);  // debounce
    // NOTE: If using DEFVAL, INT clears only if interrupt
    // condition does not exist.
    // See Fig 1-7 in datasheet.
    mcp.clearInterrupts();  // clear
  }
}

Code: Select all

// ok to include only the one needed
// both included here to make things simple for example
// #include <Adafruit_MCP23X08.h>
#include <Adafruit_MCP23X17.h>

#define LEFT_BUTTON_PIN 0  // MCP23XXX pin button is attached to
#define UP_BUTTON_PIN 1  // MCP23XXX pin button is attached to
#define DOWN_BUTTON_PIN 2  // MCP23XXX pin button is attached to
#define RIGHT_BUTTON_PIN 3  // MCP23XXX pin button is attached to
#define A_BUTTON_PIN 4  // MCP23XXX pin button is attached to
#define B_BUTTON_PIN 5  // MCP23XXX pin button is attached to
#define INT_PIN 12      // microcontroller pin attached to INTA/B


// only used for SPI
#define CS_PIN 6

// uncomment appropriate line
// Adafruit_MCP23X08 mcp;
Adafruit_MCP23X17 mcp;

void setup() {
  Serial.begin(9600);
  //while (!Serial);
  Serial.println("MCP23xxx Combo Test!");

  // uncomment appropriate mcp.begin
  if (!mcp.begin_I2C()) {
  //if (!mcp.begin_SPI(CS_PIN)) {
    Serial.println("Error.");
    while (1);
  }

  // configure MCU pin that will read INTA/B state
  // pinMode(INT_PIN, INPUT);

  // configure button pins for input with pull up
  mcp.pinMode(LEFT_BUTTON_PIN, INPUT_PULLUP);
  mcp.pinMode(UP_BUTTON_PIN, INPUT_PULLUP);
  mcp.pinMode(DOWN_BUTTON_PIN, INPUT_PULLUP);
  mcp.pinMode(RIGHT_BUTTON_PIN, INPUT_PULLUP);
  mcp.pinMode(A_BUTTON_PIN, INPUT_PULLUP);
  mcp.pinMode(B_BUTTON_PIN, INPUT_PULLUP);

  // enable interrupt on button_pins
  mcp.setupInterruptPin(LEFT_BUTTON_PIN, CHANGE);
  mcp.setupInterruptPin(UP_BUTTON_PIN, CHANGE);
  mcp.setupInterruptPin(DOWN_BUTTON_PIN, CHANGE);
  mcp.setupInterruptPin(RIGHT_BUTTON_PIN, CHANGE);
  mcp.setupInterruptPin(A_BUTTON_PIN, CHANGE);
  mcp.setupInterruptPin(B_BUTTON_PIN, CHANGE);

  attachInterrupt(digitalPinToInterrupt(INT_PIN), mcpInterrupt, FALLING);

  Serial.println("Looping...");
}

void loop() {
}

void mcpInterrupt() 
{
  // static unsigned long last_interrupt_time = 0;
  // unsigned long interrupt_time = millis();
  // // If interrupts come faster than 200ms, assume it's a bounce and ignore
  // if (interrupt_time - last_interrupt_time > 200) 
  // {
    Serial.print("Interrupt detected on pin: ");
    Serial.println(mcp.getLastInterruptPin());
    Serial.print("Pin states at time of interrupt: 0b");
    Serial.println(mcp.getCapturedInterrupt(), 2);
    mcp.clearInterrupts();  // clear
  // }
  // last_interrupt_time = interrupt_time;
  
}