Merge pull request #3 from yanzixiang/master

Add support for other Wire buses

Author: blemasle

README.md

@@ -20,4 +20,5 @@ Unlike most Arduino library, no default instance is created when the library is
 MCP23017 mcp = MCP23017(0x24);
 ```
 
+Additionaly, you can specify the `Wire` instance to use as a second argument. For instance `MCP23017(0x24, Wire1)`.  
 See included examples for furher usage.

library.properties

@@ -1,5 +1,5 @@
 name=MCP23017
-version=1.0.1
+version=1.1.0
 author=Bertrand Lemasle
 maintainer=Bertrand Lemasle
 sentence=MCP23017 I2C Port expander library.

src/MCP23017.cpp

@@ -1,7 +1,8 @@
 #include "MCP23017.h"
 
-MCP23017::MCP23017(uint8_t address) {
+MCP23017::MCP23017(uint8_t address, TwoWire& bus = Wire) {
 	_deviceAddr = address;
+	_bus = &bus;
 }
 
 MCP23017::~MCP23017() {}
@@ -100,39 +101,39 @@ uint16_t MCP23017::read()
 
 void MCP23017::writeRegister(MCP23017_REGISTER reg, uint8_t value)
 {
-	Wire.beginTransmission(_deviceAddr);
-	Wire.write(static_cast<uint8_t>(reg));
-	Wire.write(value);
-	Wire.endTransmission();
+	_bus->beginTransmission(_deviceAddr);
+	_bus->write(static_cast<uint8_t>(reg));
+	_bus->write(value);
+	_bus->endTransmission();
 }
 
 void MCP23017::writeRegister(MCP23017_REGISTER reg, uint8_t portA, uint8_t portB)
 {
-	Wire.beginTransmission(_deviceAddr);
-	Wire.write(static_cast<uint8_t>(reg));
-	Wire.write(portA);
-	Wire.write(portB);
-	Wire.endTransmission();
+	_bus->beginTransmission(_deviceAddr);
+	_bus->write(static_cast<uint8_t>(reg));
+	_bus->write(portA);
+	_bus->write(portB);
+	_bus->endTransmission();
 }
 
 
 uint8_t MCP23017::readRegister(MCP23017_REGISTER reg)
 {
-	Wire.beginTransmission(_deviceAddr);
-	Wire.write(static_cast<uint8_t>(reg));
-	Wire.endTransmission();
-	Wire.requestFrom(_deviceAddr, (uint8_t)1);
-	return Wire.read();
+	_bus->beginTransmission(_deviceAddr);
+	_bus->write(static_cast<uint8_t>(reg));
+	_bus->endTransmission();
+	_bus->requestFrom(_deviceAddr, (uint8_t)1);
+	return _bus->read();
 }
 
 void MCP23017::readRegister(MCP23017_REGISTER reg, uint8_t& portA, uint8_t& portB)
 {
-	Wire.beginTransmission(_deviceAddr);
-	Wire.write(static_cast<uint8_t>(reg));
-	Wire.endTransmission();
-	Wire.requestFrom(_deviceAddr, (uint8_t)2);
-	portA = Wire.read();
-	portB = Wire.read();
+	_bus->beginTransmission(_deviceAddr);
+	_bus->write(static_cast<uint8_t>(reg));
+	_bus->endTransmission();
+	_bus->requestFrom(_deviceAddr, (uint8_t)2);
+	portA = _bus->read();
+	portB = _bus->read();
 }
 
 #ifdef _MCP23017_INTERRUPT_SUPPORT_

src/MCP23017.h

@@ -58,12 +58,13 @@ inline MCP23017_REGISTER operator+(MCP23017_REGISTER a, MCP23017_PORT b) {
 class MCP23017
 {
 private:
+	TwoWire* _bus;
 	uint8_t _deviceAddr;
 public:
 	/**
 	 * Instantiates a new instance to interact with a MCP23017 at the specified address.
 	 */
-	MCP23017(uint8_t address);
+	MCP23017(uint8_t address, TwoWire& bus = Wire);
 	~MCP23017();
 #ifdef _DEBUG
 	void debug();