diff --git a/src/PortIOE.h b/src/PortIOE.h
index 3406e7a..83152a1 100644
--- a/src/PortIOE.h
+++ b/src/PortIOE.h
@@ -13,14 +13,14 @@ AVR port classes do not need a similar class because PORTx is global in the Ardu
 
 Instantiation
  ------------
-Example PortIOE::ADDR initilization:
-    const uint8_t PortIOE::ADDR = 0x18;
-Be careful with the ADDR.
+Example PortIOE::DEVICE_ADDR initilization:
+    const uint8_t PortIOE::DEVICE_ADDR = 0x18;
+Be careful with the DEVICE_ADDR.
 Table 6 in PCA9655E datasheet lists 8-bit versions of I2C addresses.
 The Arduino Wire library uses 7-bit addresses throughout, so drop the low bit.
 For example, I2C address with AD2=GND AD1=SCL AD0=SCL,
-    Table 6 lists      8-bit ADDR = 0x30 (b 00110000)
-    while Arduino uses 7-bit ADDR = 0x18 (b 00011000)
+    Table 6 lists      8-bit DEVICE_ADDR = 0x30 (b 00110000)
+    while Arduino uses 7-bit DEVICE_ADDR = 0x18 (b 00011000)
 http://playground.arduino.cc/Main/WireLibraryDetailedReference
 The PCA9655E data sheet is on http://www.onsemi.com/pub_link/Collateral/PCA9655E-D.PDF
 
@@ -39,7 +39,7 @@ Example instantiation for portB with active high rows on pins 0,1,2:
 */
 struct PortIOE
 {
-    static const uint8_t ADDR;                  //I2C address
+    static const uint8_t DEVICE_ADDR;
     const uint8_t num;                          //port number
     uint8_t outputVal;                          //bitwise value of output register
 
diff --git a/src/PortRead_MCP23S17.cpp b/src/PortRead_MCP23S17.cpp
index a4e65fc..d7e2b44 100644
--- a/src/PortRead_MCP23S17.cpp
+++ b/src/PortRead_MCP23S17.cpp
@@ -22,13 +22,13 @@ void PortRead_MCP23S17::begin(const uint8_t strobeOn)
     SPI.beginTransaction(SPISettings (SPI_CLOCK_DIV8, MSBFIRST, SPI_MODE0)); //control SPI bus todo is slow clock needed?
 
     digitalWrite(SS, LOW);                      //enable Slave Select
-      SPI.transfer(port.ADDR << 1);             //write command
+      SPI.transfer(port.DEVICE_ADDR << 1);             //write command
       SPI.transfer(port.num);                   //configure IODIR
       SPI.transfer(readPins);                   //0=output (for LED), 1=input (for read)
     digitalWrite(SS, LOW);                      //enable Slave Select
 
     digitalWrite(SS, HIGH);                     //disable Slave Select
-      SPI.transfer(port.ADDR << 1);             //write command
+      SPI.transfer(port.DEVICE_ADDR << 1);             //write command
       SPI.transfer(port.num + 0x0C);            //configure GPPU
       SPI.transfer(pullUp);                     //0=pull-up disabled (for LED), 1=pull-up enabled (for read)
     digitalWrite(SS, HIGH);                     //disable Slave Select
@@ -45,7 +45,7 @@ uint8_t PortRead_MCP23S17::read()
     uint8_t portState;                          //bit wise
 
     digitalWrite(SS, LOW);                      //enable Slave Select
-      SPI.transfer(port.ADDR << 1 | 1);         //read command
+      SPI.transfer(port.DEVICE_ADDR << 1 | 1);         //read command
       SPI.transfer(port.num + 0x12);            //GPIO register address to read data from
       portState = SPI.transfer(0);              //save the data (0 is dummy data to send)
     digitalWrite(SS, HIGH);                     //disable Slave Select
diff --git a/src/PortRead_PCA9655E.cpp b/src/PortRead_PCA9655E.cpp
index 8c11529..9d4ddeb 100644
--- a/src/PortRead_PCA9655E.cpp
+++ b/src/PortRead_PCA9655E.cpp
@@ -10,7 +10,7 @@ PortRead_PCA9655E::PortRead_PCA9655E (PortIOE& port, const uint8_t readPins)
 
 void PortRead_PCA9655E::begin()
 {
-    Wire.beginTransmission(port.ADDR);
+    Wire.beginTransmission(port.DEVICE_ADDR);
     Wire.write(configurationByteCommand);
     Wire.write(readPins);    //0=configure as output (for LED), 1=configure as input (for read)
     Wire.endTransmission();
@@ -21,11 +21,11 @@ returns port value
 */
 uint8_t PortRead_PCA9655E::read()
 {
-    Wire.beginTransmission(port.ADDR);
+    Wire.beginTransmission(port.DEVICE_ADDR);
     Wire.write(inputByteCommand);               //input immediately before requestFrom
     Wire.endTransmission(false);                //PCA9655E needs false to send a restart
 
-    Wire.requestFrom(port.ADDR, 1u);            //request one byte from input port
+    Wire.requestFrom(port.DEVICE_ADDR, 1u);            //request one byte from input port
 
     return Wire.read();
 }
diff --git a/src/PortWrite_MCP23S17.cpp b/src/PortWrite_MCP23S17.cpp
index 81c461a..6d48ce2 100644
--- a/src/PortWrite_MCP23S17.cpp
+++ b/src/PortWrite_MCP23S17.cpp
@@ -5,7 +5,7 @@
 void PortWrite_MCP23S17::writePort(const uint8_t registerAddr, const uint8_t data)
 {
     digitalWrite(SS, LOW);                      //enable Slave Select
-      SPI.transfer(port.ADDR << 1);             //write command
+      SPI.transfer(port.DEVICE_ADDR << 1);             //write command
       SPI.transfer(registerAddr);               //register address to write data to
       SPI.transfer(data);                       //data
     digitalWrite(SS, HIGH);                     //disable Slave Select
diff --git a/src/PortWrite_PCA9655E.cpp b/src/PortWrite_PCA9655E.cpp
index 85909fb..2e1677f 100644
--- a/src/PortWrite_PCA9655E.cpp
+++ b/src/PortWrite_PCA9655E.cpp
@@ -12,7 +12,7 @@ Otherwise readPins could be overwritten.
 */
 void PortWrite_PCA9655E::begin()
 {
-    Wire.beginTransmission(port.ADDR);
+    Wire.beginTransmission(port.DEVICE_ADDR);
     Wire.write(configurationByteCommand);
     Wire.write(0);                              //0=configure as output (for strobe pins and LED)
     Wire.endTransmission();
@@ -35,7 +35,7 @@ void PortWrite_PCA9655E::write(const uint8_t pin, const bool value)
         port.outputVal |= pin;                  //set pin output to high
     }
 
-    Wire.beginTransmission(port.ADDR);
+    Wire.beginTransmission(port.DEVICE_ADDR);
     Wire.write(outputByteCommand);
     Wire.write(port.outputVal);
     Wire.endTransmission();
diff --git a/tutorials/keybrd_4c_split_with_IOE/keybrd_4c_split_with_IOE.ino b/tutorials/keybrd_4c_split_with_IOE/keybrd_4c_split_with_IOE.ino
index 656f571..26b609d 100644
--- a/tutorials/keybrd_4c_split_with_IOE/keybrd_4c_split_with_IOE.ino
+++ b/tutorials/keybrd_4c_split_with_IOE/keybrd_4c_split_with_IOE.ino
@@ -39,7 +39,7 @@ uint8_t readPins[] = {14, 15};
 const bool Scanner_Port::STROBE_ON = HIGH;      //active high
 const bool Scanner_Port::STROBE_OFF = LOW;
 
-const uint8_t PortIOE::ADDR = 0x18;
+const uint8_t PortIOE::DEVICE_ADDR = 0x18;
 
 // ------------------ PORT 1 -------------------
 PortIOE port1_R(1, 0);
diff --git a/unit_tests/PortRead_MCP23S17/PortRead_MCP23S17.ino b/unit_tests/PortRead_MCP23S17/PortRead_MCP23S17.ino
index 936a23f..1886c50 100644
--- a/unit_tests/PortRead_MCP23S17/PortRead_MCP23S17.ino
+++ b/unit_tests/PortRead_MCP23S17/PortRead_MCP23S17.ino
@@ -14,7 +14,7 @@ http://arduino.stackexchange.com/questions/28792/reading-an-mcp23s17-i-o-expande
 const bool Scanner_Port::STROBE_ON = LOW;
 const bool Scanner_Port::STROBE_OFF = HIGH;
 
-const uint8_t PortIOE::ADDR = 0x20;             //MCP23S17 address, all 3 ADDR pins are grounded
+const uint8_t PortIOE::DEVICE_ADDR = 0x20;      //MCP23S17 address, all 3 ADDR pins are grounded
 PortIOE portB(1, 0);
 
 PortRead_MCP23S17 portBRead(portB, ~0);
diff --git a/unit_tests/PortWrite_MCP23S17/PortRead_MCP23S17.ino b/unit_tests/PortWrite_MCP23S17/PortRead_MCP23S17.ino
index 2901f5e..dc4cb3f 100644
--- a/unit_tests/PortWrite_MCP23S17/PortRead_MCP23S17.ino
+++ b/unit_tests/PortWrite_MCP23S17/PortRead_MCP23S17.ino
@@ -11,7 +11,7 @@ MCP23S17 on 3.3v does not output enough power to reliable light LEDs
 #include "PortIOE.h"
 #include "PortWrite_MCP23S17.h"
 
-const uint8_t PortIOE::ADDR = 0x20;             //MCP23S17 address, all 3 ADDR pins are grounded
+const uint8_t PortIOE::DEVICE_ADDR = 0x20;      //MCP23S17 address, all 3 ADDR pins are grounded
 PortIOE portA(0, 0);
 
 PortWrite_MCP23S17 portAWrite(portA);           //PortAWrite needed for begin()