diff --git a/src/MCP23017.cpp b/src/MCP23017.cpp
index edd69cd..bb7d56a 100644
--- a/src/MCP23017.cpp
+++ b/src/MCP23017.cpp
@@ -12,7 +12,7 @@ MCP23017::MCP23017(TwoWire& bus) {
 
 MCP23017::~MCP23017() {}
 
-void MCP23017::init()
+bool MCP23017::init()
 {
 	//BANK = 	0 : sequential register addresses
 	//MIRROR = 	0 : use configureInterrupt 
@@ -24,31 +24,34 @@ void MCP23017::init()
 	//INTPOL = 	0 : interrupt active low
 	//UNIMPLMENTED 	0 : unimplemented: Read as ‘0’
 
-	writeRegister(MCP23017Register::IOCON, 0b00100000);
+	bool retval = writeRegister(MCP23017Register::IOCON, 0b00100000);
 
 	//enable all pull up resistors (will be effective for input pins only)
-	writeRegister(MCP23017Register::GPPU_A, 0xFF, 0xFF);
+	retval &= writeRegister(MCP23017Register::GPPU_A, 0xFF, 0xFF);
+
+	return retval;
 }
 
-void MCP23017::begin()
+bool MCP23017::begin()
 {
-	init();
+	return init();
 }
 
-void MCP23017::begin(uint8_t address)
+bool MCP23017::begin(uint8_t address)
 {
 	_deviceAddr = address;
-	begin();
+	return begin();
 }
 
-void MCP23017::portMode(MCP23017Port port, uint8_t directions, uint8_t pullups, uint8_t inverted)
+bool MCP23017::portMode(MCP23017Port port, uint8_t directions, uint8_t pullups, uint8_t inverted)
 {
-	writeRegister(MCP23017Register::IODIR_A + port, directions);
-	writeRegister(MCP23017Register::GPPU_A + port, pullups);
-	writeRegister(MCP23017Register::IPOL_A + port, inverted);
+	bool retVal = writeRegister(MCP23017Register::IODIR_A + port, directions);
+	retVal &= writeRegister(MCP23017Register::GPPU_A + port, pullups);
+	retVal &= writeRegister(MCP23017Register::IPOL_A + port, inverted);
+	return retVal;
 }
 
-void MCP23017::pinMode(uint8_t pin, uint8_t mode, bool inverted)
+bool MCP23017::pinMode(uint8_t pin, uint8_t mode, bool inverted)
 {
 	MCP23017Register iodirreg = MCP23017Register::IODIR_A;
 	MCP23017Register pullupreg = MCP23017Register::GPPU_A;
@@ -75,12 +78,13 @@ void MCP23017::pinMode(uint8_t pin, uint8_t mode, bool inverted)
 	if(inverted) bitSet(pol, pin);
 	else bitClear(pol, pin);
 
-	writeRegister(iodirreg, iodir);
-	writeRegister(pullupreg, pull);
-	writeRegister(polreg, pol);
+	bool retVal = writeRegister(iodirreg, iodir);
+	retVal &= writeRegister(pullupreg, pull);
+	retVal &= writeRegister(polreg, pol);
+	return retVal;
 }
 
-void MCP23017::digitalWrite(uint8_t pin, uint8_t state)
+bool MCP23017::digitalWrite(uint8_t pin, uint8_t state)
 {
 	MCP23017Register gpioreg = MCP23017Register::GPIO_A;
 	uint8_t gpio;
@@ -94,7 +98,7 @@ void MCP23017::digitalWrite(uint8_t pin, uint8_t state)
 	if(state == HIGH) bitSet(gpio, pin);
 	else bitClear(gpio, pin);
 
-	writeRegister(gpioreg, gpio);
+	return writeRegister(gpioreg, gpio);
 }
 
 uint8_t MCP23017::digitalRead(uint8_t pin)
@@ -112,14 +116,14 @@ uint8_t MCP23017::digitalRead(uint8_t pin)
 	return LOW;
 }
 
-void MCP23017::writePort(MCP23017Port port, uint8_t value)
+bool MCP23017::writePort(MCP23017Port port, uint8_t value)
 {
-	writeRegister(MCP23017Register::GPIO_A + port, value);
+	return writeRegister(MCP23017Register::GPIO_A + port, value);
 }
 
-void MCP23017::write(uint16_t value)
+bool MCP23017::write(uint16_t value)
 {
-	writeRegister(MCP23017Register::GPIO_A, lowByte(value), highByte(value));
+	return writeRegister(MCP23017Register::GPIO_A, lowByte(value), highByte(value));
 }
 
 uint8_t MCP23017::readPort(MCP23017Port port)
@@ -135,21 +139,23 @@ uint16_t MCP23017::read()
 	return a | b << 8;
 }
 
-void MCP23017::writeRegister(MCP23017Register reg, uint8_t value)
+bool MCP23017::writeRegister(MCP23017Register reg, uint8_t value)
 {
 	_bus->beginTransmission(_deviceAddr);
 	_bus->write(static_cast<uint8_t>(reg));
 	_bus->write(value);
-	_bus->endTransmission();
+	uint8_t retval = _bus->endTransmission();
+	return !retval;
 }
 
-void MCP23017::writeRegister(MCP23017Register reg, uint8_t portA, uint8_t portB)
+bool MCP23017::writeRegister(MCP23017Register reg, uint8_t portA, uint8_t portB)
 {
 	_bus->beginTransmission(_deviceAddr);
 	_bus->write(static_cast<uint8_t>(reg));
 	_bus->write(portA);
 	_bus->write(portB);
-	_bus->endTransmission();
+	uint8_t retval = _bus->endTransmission();
+	return !retval;
 }
 
 
@@ -157,77 +163,79 @@ uint8_t MCP23017::readRegister(MCP23017Register reg)
 {
 	_bus->beginTransmission(_deviceAddr);
 	_bus->write(static_cast<uint8_t>(reg));
-	_bus->endTransmission();
-	_bus->requestFrom(_deviceAddr, (uint8_t)1);
+	uint8_t retval = _bus->endTransmission();
+	retval &= _bus->requestFrom(_deviceAddr, (uint8_t)1);
 	return _bus->read();
 }
 
-void MCP23017::readRegister(MCP23017Register reg, uint8_t& portA, uint8_t& portB)
+bool MCP23017::readRegister(MCP23017Register reg, uint8_t& portA, uint8_t& portB)
 {
 	_bus->beginTransmission(_deviceAddr);
 	_bus->write(static_cast<uint8_t>(reg));
-	_bus->endTransmission();
-	_bus->requestFrom(_deviceAddr, (uint8_t)2);
+	uint8_t retval = _bus->endTransmission();
+	retval &= _bus->requestFrom(_deviceAddr, (uint8_t)2);
 	portA = _bus->read();
 	portB = _bus->read();
+	return !retval;
 }
 
 #ifdef _MCP23017_INTERRUPT_SUPPORT_
 
-void MCP23017::interruptMode(MCP23017InterruptMode intMode)
+bool MCP23017::interruptMode(MCP23017InterruptMode intMode)
 {
 	uint8_t iocon = readRegister(MCP23017Register::IOCON);
 	if(intMode == MCP23017InterruptMode::Or) iocon |= static_cast<uint8_t>(MCP23017InterruptMode::Or);
 	else iocon &= ~(static_cast<uint8_t>(MCP23017InterruptMode::Or));
 
-	writeRegister(MCP23017Register::IOCON, iocon);
+	return writeRegister(MCP23017Register::IOCON, iocon);
 }
 
-void MCP23017::interrupt(MCP23017Port port, uint8_t mode)
+bool MCP23017::interrupt(MCP23017Port port, uint8_t mode)
 {
 	MCP23017Register defvalreg = MCP23017Register::DEFVAL_A + port;
 	MCP23017Register intconreg = MCP23017Register::INTCON_A + port;
 
 	//enable interrupt for port
-	writeRegister(MCP23017Register::GPINTEN_A + port, 0xFF);
+	bool retVal = writeRegister(MCP23017Register::GPINTEN_A + port, 0xFF);
 	switch(mode)
 	{
 	case CHANGE:
 		//interrupt on change
-		writeRegister(intconreg, 0);
+		retVal &= writeRegister(intconreg, 0);
 		break;
 	case FALLING:
 		//interrupt falling : compared against defval, 0xff
-		writeRegister(intconreg, 0xFF);
-		writeRegister(defvalreg, 0xFF);
+		retVal &= writeRegister(intconreg, 0xFF);
+		retVal &= writeRegister(defvalreg, 0xFF);
 		break;
 	case RISING:
 		//interrupt rising : compared against defval, 0x00
-		writeRegister(intconreg, 0xFF);
-		writeRegister(defvalreg, 0x00);
+		retVal &= writeRegister(intconreg, 0xFF);
+		retVal &= writeRegister(defvalreg, 0x00);
 		break;
 	}
+	return retVal;
 }
 
-void MCP23017::interruptedBy(uint8_t& portA, uint8_t& portB)
+bool MCP23017::interruptedBy(uint8_t& portA, uint8_t& portB)
 {
-	readRegister(MCP23017Register::INTF_A, portA, portB);
+	return readRegister(MCP23017Register::INTF_A, portA, portB);
 }
 
-void MCP23017::disableInterrupt(MCP23017Port port)
+bool MCP23017::disableInterrupt(MCP23017Port port)
 {
-	writeRegister(MCP23017Register::GPINTEN_A + port, 0x00);
+	return writeRegister(MCP23017Register::GPINTEN_A + port, 0x00);
 }
 
-void MCP23017::clearInterrupts()
+bool MCP23017::clearInterrupts()
 {
 	uint8_t a, b;
-	clearInterrupts(a, b);
+	return clearInterrupts(a, b);
 }
 
-void MCP23017::clearInterrupts(uint8_t& portA, uint8_t& portB)
+bool MCP23017::clearInterrupts(uint8_t& portA, uint8_t& portB)
 {
-	readRegister(MCP23017Register::INTCAP_A, portA, portB);
+	return readRegister(MCP23017Register::INTCAP_A, portA, portB);
 }
 
 #endif
diff --git a/src/MCP23017.h b/src/MCP23017.h
index b66df22..443f6fb 100644
--- a/src/MCP23017.h
+++ b/src/MCP23017.h
@@ -100,12 +100,12 @@ class MCP23017
 	/**
 	 * Uses the I2C address set during construction. Implicitly calls init().
 	 */
-	void begin();
+	bool begin();
 	/**
 	 * Overrides the I2C address set by the constructor. Implicitly calls begin().
 
 	 */
-	void begin(uint8_t address);
+	bool begin(uint8_t address);
 	/**
 	 * Initializes the chip with the default configuration.
 	 * Enables Byte mode (IOCON.BANK = 0 and IOCON.SEQOP = 1).
@@ -113,7 +113,7 @@ class MCP23017
 	 * 
 	 * See "3.2.1 Byte mode and Sequential mode".
 	 */
-	void init();
+	bool init();
 	/**
 	 * Controls the pins direction on a whole port at once.
 	 * 
@@ -122,7 +122,7 @@ class MCP23017
 	 * 
 	 * See "3.5.1 I/O Direction register".
 	 */
-	void portMode(MCP23017Port port, uint8_t directions, uint8_t pullups = 0xFF, uint8_t inverted = 0x00);
+	bool portMode(MCP23017Port port, uint8_t directions, uint8_t pullups = 0xFF, uint8_t inverted = 0x00);
 	/**
 	 * Controls a single pin direction. 
 	 * Pin 0-7 for port A, 8-15 fo port B.
@@ -138,7 +138,7 @@ class MCP23017
 	 * This library pinMode function behaves like Arduino's standard pinMode for consistency.
 	 * [ OUTPUT | INPUT | INPUT_PULLUP ]
 	 */
-	void pinMode(uint8_t pin, uint8_t mode, bool inverted = false);
+	bool pinMode(uint8_t pin, uint8_t mode, bool inverted = false);
 
 	/**
 	 * Writes a single pin state.
@@ -149,7 +149,7 @@ class MCP23017
 	 * 
 	 * See "3.5.10 Port register".
 	 */
-	void digitalWrite(uint8_t pin, uint8_t state);
+	bool digitalWrite(uint8_t pin, uint8_t state);
 	/**
 	 * Reads a single pin state.
 	 * Pin 0-7 for port A, 8-15 for port B.
@@ -169,7 +169,7 @@ class MCP23017
 	 * 
 	 * See "3.5.10 Port register".
 	 */
-	void writePort(MCP23017Port port, uint8_t value);
+	bool writePort(MCP23017Port port, uint8_t value);
 	/**
 	 * Writes pins state to both ports.
 	 * 
@@ -178,7 +178,7 @@ class MCP23017
 	 * 
 	 * See "3.5.10 Port register".
 	 */
-	void write(uint16_t value);
+	bool write(uint16_t value);
 
 	/**
 	 * Reads pins state for a whole port.
@@ -202,7 +202,7 @@ class MCP23017
 	/**
 	 * Writes a single register value.
 	 */
-	void writeRegister(MCP23017Register reg, uint8_t value);
+	bool writeRegister(MCP23017Register reg, uint8_t value);
 	/**
 	 * Writes values to a register pair.
 	 * 
@@ -210,7 +210,7 @@ class MCP23017
 	 * you have to supply a portA register address to reg. Otherwise, values
 	 * will be reversed due to the way the MCP23017 works in Byte mode.
 	 */
-	void writeRegister(MCP23017Register reg, uint8_t portA, uint8_t portB);
+	bool writeRegister(MCP23017Register reg, uint8_t portA, uint8_t portB);
 	/**
 	 * Reads a single register value.
 	 */
@@ -222,7 +222,7 @@ class MCP23017
 	 * you have to supply a portA register address to reg. Otherwise, values
 	 * will be reversed due to the way the MCP23017 works in Byte mode.
 	 */
-	void readRegister(MCP23017Register reg, uint8_t& portA, uint8_t& portB);
+	bool readRegister(MCP23017Register reg, uint8_t& portA, uint8_t& portB);
 
 #ifdef _MCP23017_INTERRUPT_SUPPORT_
 
@@ -234,28 +234,28 @@ class MCP23017
 	 * Controls the IOCON.MIRROR bit. 
 	 * See "3.5.6 Configuration register".
 	 */
-	void interruptMode(MCP23017InterruptMode intMode);
+	bool interruptMode(MCP23017InterruptMode intMode);
 	/**
 	 * Configures interrupt registers using an Arduino-like API.
 	 * mode can be one of CHANGE, FALLING or RISING.
 	 */
-	void interrupt(MCP23017Port port, uint8_t mode);
+	bool interrupt(MCP23017Port port, uint8_t mode);
 	/**
 	 * Disable interrupts for the specified port.
 	 */
-	void disableInterrupt(MCP23017Port port);
+	bool disableInterrupt(MCP23017Port port);
 	/**
 	 * Reads which pin caused the interrupt.
 	 */
-	void interruptedBy(uint8_t& portA, uint8_t& portB);
+	bool interruptedBy(uint8_t& portA, uint8_t& portB);
 	/**
 	 * Clears interrupts on both ports.
 	 */
-	void clearInterrupts();
+	bool clearInterrupts();
 	/**
 	 * Clear interrupts on both ports. Returns port values at the time the interrupt occured.
 	 */
-	void clearInterrupts(uint8_t& portA, uint8_t& portB);
+	bool clearInterrupts(uint8_t& portA, uint8_t& portB);
 
 #endif
 };