Adafruit_MCP23XXX.h

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#ifndef __ADAFRUIT_MCP23XXX_H__
#define __ADAFRUIT_MCP23XXX_H__

#include <Adafruit_BusIO_Register.h>
#include <Adafruit_I2CDevice.h>
#include <Adafruit_SPIDevice.h>
#include <Arduino.h>

// registers
#define MCP23XXX_IODIR 0x00   
#define MCP23XXX_IPOL 0x01    
#define MCP23XXX_GPINTEN 0x02 
#define MCP23XXX_DEFVAL                                                        \
  0x03 
#define MCP23XXX_INTCON 0x04 
#define MCP23XXX_IOCON 0x05  
#define MCP23XXX_GPPU 0x06   
#define MCP23XXX_INTF 0x07   
#define MCP23XXX_INTCAP 0x08 
#define MCP23XXX_GPIO 0x09   
#define MCP23XXX_OLAT 0x0A   

#define MCP23XXX_ADDR 0x20 
#define MCP23XXX_SPIREG                                                        \
  ADDRESSED_OPCODE_BIT0_LOW_TO_WRITE 

#define MCP_PORT(pin) ((pin < 8) ? 0 : 1) 

#define MCP23XXX_INT_ERR 255 

/**************************************************************************/
/**************************************************************************/
class Adafruit_MCP23XXX {
public:
  // init
  bool begin_I2C(uint8_t i2c_addr = MCP23XXX_ADDR, TwoWire *wire = &Wire);
  bool begin_SPI(uint8_t cs_pin, SPIClass *theSPI = &SPI,
                 uint8_t _hw_addr = 0x00);
  bool begin_SPI(int8_t cs_pin, int8_t sck_pin, int8_t miso_pin,
                 int8_t mosi_pin, uint8_t _hw_addr = 0x00);

  // main Arduino API methods
  void pinMode(uint8_t pin, uint8_t mode);
  uint8_t digitalRead(uint8_t pin);
  void digitalWrite(uint8_t pin, uint8_t value);

  // bulk access
  uint8_t readGPIO(uint8_t port = 0);
  void writeGPIO(uint8_t value, uint8_t port = 0);

  // interrupts
  void setupInterrupts(bool mirroring, bool openDrain, uint8_t polarity);
  void setupInterruptPin(uint8_t pin, uint8_t mode = CHANGE);
  void disableInterruptPin(uint8_t pin);
  void clearInterrupts();
  uint8_t getLastInterruptPin();
  uint16_t getCapturedInterrupt();

protected:
  Adafruit_I2CDevice *i2c_dev = nullptr; 
  Adafruit_SPIDevice *spi_dev = nullptr; 
  uint8_t pinCount;                      
  uint8_t hw_addr;                       
  uint16_t getRegister(uint8_t baseAddress, uint8_t port = 0);

private:
  uint8_t buffer[4];
};

#endif