diff --git a/src/PortIOE.h b/src/PortIOE.h
index 7ba4cf8..041e7c6 100644
--- a/src/PortIOE.h
+++ b/src/PortIOE.h
@@ -6,7 +6,7 @@
 
 PortIOE contains outputVal, the value of a port's output register.
 outputVal is used for port manipulation by classes PortWrite and LED.
-One port's outputVal can be shared by one PortWrite object and multiple LED objects.
+One port's outputVal can be shared by strobe pins and multiple LED pins.
 
 PortIOE is only used by I/O expander port classes.
 AVR port classes do not need a similar class because PORTx is global in the Arduino library.
@@ -32,7 +32,7 @@ struct PortIOE
     const uint8_t num;                          //port number
     uint8_t outputVal;                          //bitwise value of output register for LEDs
 
-    PortIOE(const uint8_t portNumber, uint8_t outputVal)
-        : num(portNumber), outputVal(outputVal) {}
+    PortIOE(const uint8_t portNumber)
+        : num(portNumber), outputVal(0) {}
 };
 #endif
diff --git a/src/PortRead_MCP23S17.cpp b/src/PortRead_MCP23S17.cpp
index f04f1de..1071dc9 100644
--- a/src/PortRead_MCP23S17.cpp
+++ b/src/PortRead_MCP23S17.cpp
@@ -1,7 +1,7 @@
 #include "PortRead_MCP23S17.h"
 
-/*
-begin() is called from Scanner_IOE::begin().
+/* begin() is called from Scanner_IOE::begin().
+Configures port to to read (input with pullup enabled).
 */
 void PortRead_MCP23S17::begin(const uint8_t strobeOn)
 {
@@ -14,16 +14,6 @@ void PortRead_MCP23S17::begin(const uint8_t strobeOn)
         pullUp = 0;
     }
 
-Keyboard.print("\npullUp=");//todo
-Keyboard.print(pullUp);
-/*
-    //todo these 4 lines are duplicated in PortWrite_MCP23S17::begin(), which is called first
-    pinMode(SS, OUTPUT);                        //configure controller's Slave Select pin to output
-    digitalWrite(SS, HIGH);                     //disable Slave Select
-    SPI.begin();
-    SPI.beginTransaction(SPISettings (SPI_CLOCK_DIV8, MSBFIRST, SPI_MODE0)); //control SPI bus todo is slow clock needed?
-    //SPI.endTransaction() not called to release SPI bus because keyboard only has one SPI device.
-*/
     digitalWrite(SS, LOW);                      //enable Slave Select
       SPI.transfer(port.DEVICE_ADDR << 1);      //write command
       SPI.transfer(port.num);                   //configure IODIR
@@ -37,15 +27,15 @@ Keyboard.print(pullUp);
     digitalWrite(SS, HIGH);                     //disable Slave Select
 }
 
-/*
-read() returns portState.
+/* read() returns portState.
+Only portState bits of readPins are valid.
 */
 uint8_t PortRead_MCP23S17::read()
 {
     uint8_t portState;                          //bit wise
 
     digitalWrite(SS, LOW);                      //enable Slave Select
-      SPI.transfer(port.DEVICE_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_MCP23S17.h b/src/PortRead_MCP23S17.h
index dd81092..848bba9 100644
--- a/src/PortRead_MCP23S17.h
+++ b/src/PortRead_MCP23S17.h
@@ -9,21 +9,28 @@
 
 /* One MCP23S17 I/O expander port connected to matrix columns.
 
-Instantiation todo
+This class has Slave Select hardcoded to Arduino Pin 10.
+Arduino Pin 10 avoids the speed penalty of digitalWrite.
+
+Instantiation
  ------------
 readPins parameter is port's bitwise pin configuration
     1=configure as input (for pins connected to column)
     0=configure as output (for LED or not connected to a column)
-
-Example instantiation for column port 0, with pins 2 and 3 connected to columns:
-    PortIOE port0(0, 0);
-    PortRead_MCP23S17 colPort0(port0, 2<<0 | 1<<3 );
-Example instantiation for column port 1, with pins 2 and 3 connected to columns:
-    PortIOE port1(1, 0);
-    PortRead_MCP23S17 colPort1(port1, 2<<0 | 1<<3 );
-
 readPins are read from pin 0 on up.
 
+Example instantiation with port-A pins 0 and 1 connected to Scanner_IOE columns:
+    const uint8_t PortIOE::DEVICE_ADDR = 0x20;      //MCP23S17 address, all 3 ADDR pins are grounded
+    PortIOE port_A(0);
+    PortRead_MCP23S17 portRead_A(port_A, 1<<0 | 1<<1 );
+
+Diode orientation
+ ----------------
+Diode orientation is explained in keybrd_library_user_guide.md > Diode orientation
+
+MCP23S17 data sheet
+ ------------------
+ http://www.onsemi.com/pub_link/Collateral/MCP23S17-D.PDF
 */
 class PortRead_MCP23S17 : public PortReadInterface
 {
diff --git a/src/PortRead_PCA9655E.cpp b/src/PortRead_PCA9655E.cpp
index a1ce08e..bc6c5c4 100644
--- a/src/PortRead_PCA9655E.cpp
+++ b/src/PortRead_PCA9655E.cpp
@@ -1,17 +1,18 @@
 #include "PortRead_PCA9655E.h"
 
-/*
+/* begin() is called from Scanner_IOE::begin().
+Configures port to to read (input).
 */
 void PortRead_PCA9655E::begin(const uint8_t strobeOn)
 {
     Wire.beginTransmission(port.DEVICE_ADDR);
     Wire.write(port.num + 6);                   //configuration byte command
-    Wire.write(readPins);    //0=configure as output (for LED), 1=configure as input (for read)
+    Wire.write(readPins);                       //0=output (for LED), 1=input (for read)
     Wire.endTransmission();
 }
 
-/*
-returns port value
+/* read() returns portState.
+Only portState bits of readPins are valid.
 */
 uint8_t PortRead_PCA9655E::read()
 {
diff --git a/src/PortRead_PCA9655E.h b/src/PortRead_PCA9655E.h
index 490856c..271f842 100644
--- a/src/PortRead_PCA9655E.h
+++ b/src/PortRead_PCA9655E.h
@@ -14,16 +14,20 @@ Instantiation
 readPins parameter is port's bitwise pin configuration
     1=configure as input (for pins connected to column)
     0=configure as output (for LED or not connected to a column)
-
-Example instantiation for column port 0, with pins 2 and 3 connected to columns:
-    PortIOE port0(0, 0);
-    PortRead_PCA9655E colPort0(port0, 2<<0 | 1<<3 );
-Example instantiation for column port 1, with pins 2 and 3 connected to columns:
-    PortIOE port1(1, 0);
-    PortRead_PCA9655E colPort1(port1, 2<<0 | 1<<3 );
-
 readPins are read from pin 0 on up.
 
+Example instantiation for column port 1, with pins 2 and 3 connected to columns:
+    const uint8_t PortIOE::DEVICE_ADDR = 0x20;      //PCA9655E address, all 3 ADDR pins are grounded
+    PortIOE port1(1);
+    PortRead_PCA9655E colPort1(port1, 1<<2 | 1<<3 );
+
+Diode orientation
+ ----------------
+Diode orientation is explained in keybrd_library_user_guide.md > Diode orientation
+
+PCA9655E data sheet
+ ----------------
+ http://www.onsemi.com/pub_link/Collateral/PCA9655E-D.PDF
 */
 class PortRead_PCA9655E : public PortReadInterface
 {
diff --git a/src/PortWrite_MCP23S17.cpp b/src/PortWrite_MCP23S17.cpp
index 2f0d6da..6585e4c 100644
--- a/src/PortWrite_MCP23S17.cpp
+++ b/src/PortWrite_MCP23S17.cpp
@@ -1,47 +1,46 @@
 #include "PortWrite_MCP23S17.h"
 
-/* writePort() sets registerAddr to data.
+/* push() writes data to registerAddr.
 */
-void PortWrite_MCP23S17::writePort(const uint8_t registerAddr, const uint8_t data)
+void PortWrite_MCP23S17::push(const uint8_t registerAddr, const uint8_t data)
 {
     digitalWrite(SS, LOW);                      //enable Slave Select
       SPI.transfer(port.DEVICE_ADDR << 1);      //write command
       SPI.transfer(registerAddr);               //register address to write data to
-      SPI.transfer(data);                       //data
+      SPI.transfer(data);                       //write the data
     digitalWrite(SS, HIGH);                     //disable Slave Select
 }    
 
-/* begin() is called from Scanner_IOE::begin().  Initiates SPI bus and configures write pins.
-PortRead_MCP23S17 and PortWrite_MCP23S17 should be on seperate ports on the same MCP23S17.
-Output pins can be used for strobe pins and LEDs.
+/* begin() is called from Scanner_IOE::begin().
+Initiates SPI bus and configures write pins to output.
+MCP23S17 SPI interface is 10 MHz max.
 */
 void PortWrite_MCP23S17::begin()
 {
     pinMode(SS, OUTPUT);                        //configure controller's Slave Select pin to output
     digitalWrite(SS, HIGH);                     //disable Slave Select
     SPI.begin();
-    SPI.beginTransaction(SPISettings (SPI_CLOCK_DIV8, MSBFIRST, SPI_MODE0)); //control SPI bus todo is slow clock needed?
+    SPI.beginTransaction(SPISettings (5000000, MSBFIRST, SPI_MODE0)); //control SPI bus, 5 MHz
     //SPI.endTransaction() not called to release SPI bus because keyboard only has one SPI device.
 
-    writePort(port.num, 0);                     //configure port direction (port.num) to output (0)
+    push(port.num, 0);                          //configure port direction (port.num) to output (0)
 }
 
-/*
-strobePin is bitwise, where pin being strobed is 1.
-pinLogicLevel is HIGH or LOW.
-port.outputVal can be shared by LEDs.
-The function does not reset the other pins so that they can be used for LEDs.
+/* write() sets pin output to logicLevel.
+pin is bitwise, where pin being set is 1.
+logicLevel is HIGH or LOW.
+write() does not overwrite the other pins.
 */
-void PortWrite_MCP23S17::write(const uint8_t strobePin, const bool pinLogicLevel)
+void PortWrite_MCP23S17::write(const uint8_t pin, const bool logicLevel)
 {
-    if (pinLogicLevel == LOW)
+    if (logicLevel == LOW)
     {
-        port.outputVal &= ~strobePin;           //set strobePin output to low
+        port.outputVal &= ~pin;                 //set pin output to low
     }
     else
     {
-        port.outputVal |= strobePin;            //set strobePin output to high
+        port.outputVal |= pin;                  //set pin output to high
     }
 
-    writePort(port.num + 0x12, port.outputVal); //set GPIO port pins for strobe and LEDs
+    push(port.num + 0x12, port.outputVal);      //set GPIO port pin to outputVal
 }
diff --git a/src/PortWrite_MCP23S17.h b/src/PortWrite_MCP23S17.h
index 9d5fe13..9cabb86 100644
--- a/src/PortWrite_MCP23S17.h
+++ b/src/PortWrite_MCP23S17.h
@@ -7,42 +7,35 @@
 #include "PortIOE.h"
 
 /* One MCP23S17 I/O expander port connected to matrix rows.
-MCP23S17 does not have internal pull-up resistors (PCA9535E does).
+write() can output logiclevel to strobePin, one LED pin, or multiple pins.
 
-begin() configures column port's configuration and output.
-This should normally be called once in sketch's setup().
-If PortRead_MCP23S17 is instantiated on the same port, do NOT use PortWrite_MCP23S17::begin().
-Otherwise readPins could be overwritten.
+This class has Slave Select hardcoded to Arduino Pin 10.
+Arduino Pin 10 avoids the speed penalty of digitalWrite.
 
 Instantiation
  ------------
-Example instantiation for row port 0:
-    PortIOE port0(0, 0);
-    PortWrite_MCP23S17 rowPort0(port0);
-
-Example instantiation for row port 1:
-    PortIOE port1(1, 0);
-    PortWrite_MCP23S17 rowPort1(port1);
+Example instantiation:
+    const uint8_t PortIOE::DEVICE_ADDR = 0x20;      //MCP23S17 address, all 3 ADDR pins are grounded
+    PortIOE port_B(1);
+    PortWrite_MCP23S17 portWrite_B(port_B);
 
 Diode orientation
  ----------------
 Diode orientation is explained in keybrd_library_user_guide.md > Diode orientation
 
 MCP23S17 data sheet
- ----------------
+ ------------------
  http://www.onsemi.com/pub_link/Collateral/MCP23S17-D.PDF
-
-WARNING: This class hardcodes Slave Select to Arduino Pin 10 to avoid the speed penalty of digitalWrite
 */
 
 class PortWrite_MCP23S17 : public PortWriteInterface
 {
     private:
         PortIOE& port;
-        void writePort(const uint8_t registerAddr, const uint8_t data);
+        void push(const uint8_t registerAddr, const uint8_t data);
     public:
         PortWrite_MCP23S17(PortIOE& port) : port(port) {}
         void begin();
-        virtual void write(const uint8_t pin, const bool pinLogicLevel);
+        virtual void write(const uint8_t pin, const bool logicLevel);
 };
 #endif
diff --git a/src/PortWrite_PCA9655E.cpp b/src/PortWrite_PCA9655E.cpp
index 5c23fdb..0d94cfa 100644
--- a/src/PortWrite_PCA9655E.cpp
+++ b/src/PortWrite_PCA9655E.cpp
@@ -1,8 +1,7 @@
 #include "PortWrite_PCA9655E.h"
 
-/*
-If PortRead_PCA9655E is instantiated on the same port, do NOT use PortWrite_PCA9655E::begin().
-Otherwise readPins could be overwritten.
+/* begin() is called from Scanner_IOE::begin().
+Configures write pins to output.
 */
 void PortWrite_PCA9655E::begin()
 {
@@ -10,25 +9,24 @@ void PortWrite_PCA9655E::begin()
 
     Wire.beginTransmission(port.DEVICE_ADDR);
     Wire.write(port.num + 6);                   //configuration byte command
-    Wire.write(0);                              //0=configure as output (for strobe pins and LED)
+    Wire.write(0);                              //configure all pins as output
     Wire.endTransmission();
 }
 
-/*
-strobePin is bitwise, where pin being strobed is 1.
-pinLogicLevel is HIGH or LOW.
-Does not reset the other pins because LEDs could be using some of the pins.
-Syntax is similar to Arduino DigitalWrite().
+/* write() sets pin output to logicLevel.
+pin is bitwise, where pin being strobed is 1.
+logicLevel is HIGH or LOW.
+write() does not overwrite the other pins.
 */
-void PortWrite_PCA9655E::write(const uint8_t strobePin, const bool pinLogicLevel)
+void PortWrite_PCA9655E::write(const uint8_t pin, const bool logicLevel)
 {
-    if (pinLogicLevel == LOW)                   //if strobePin low
+    if (logicLevel == LOW)                      //if pin low
     {
-        port.outputVal &= ~strobePin;           //set pin output to low
+        port.outputVal &= ~pin;                 //set pin output to low
     }
     else                                        //if strobestrobe high
     {
-        port.outputVal |= strobePin;            //set pin output to high
+        port.outputVal |= pin;                  //set pin output to high
     }
 
     Wire.beginTransmission(port.DEVICE_ADDR);
diff --git a/src/PortWrite_PCA9655E.h b/src/PortWrite_PCA9655E.h
index bbd041a..e27909c 100644
--- a/src/PortWrite_PCA9655E.h
+++ b/src/PortWrite_PCA9655E.h
@@ -7,23 +7,15 @@
 #include "PortIOE.h"
 
 /* One PCA9655E I/O expander port connected to matrix rows.
-PCA9655E does not have internal pull-up resistors (PCA9535E does).
-
-begin() configures column port's configuration and output.
-This should normally be called once in sketch's setup().
-If PortRead_PCA9655E is instantiated on the same port, do NOT use PortWrite_PCA9655E::begin().
-Otherwise readPins could be overwritten.
+write() can output logiclevel to strobePin, one LED pin, or multiple pins.
 
 Instantiation
  ------------
-Example instantiation for row port 0:
-    PortIOE port0(0, 0);
+Example instantiation:
+    const uint8_t PortIOE::DEVICE_ADDR = 0x20;      //PCA9655E address, all 3 ADDR pins are grounded
+    PortIOE port0(0);
     PortWrite_PCA9655E rowPort0(port0);
 
-Example instantiation for row port 1:
-    PortIOE port1(1, 0);
-    PortWrite_PCA9655E rowPort1(port1);
-
 Diode orientation
  ----------------
 Diode orientation is explained in keybrd_library_user_guide.md > Diode orientation
@@ -41,6 +33,6 @@ class PortWrite_PCA9655E : public PortWriteInterface
         PortWrite_PCA9655E(PortIOE& port) : port(port) {}
         void begin();
 
-        virtual void write(const uint8_t strobePin, const bool pinLogicLevel);
+        virtual void write(const uint8_t pin, const bool logicLevel);
 };
 #endif
diff --git a/src/Scanner_IOE.cpp b/src/Scanner_IOE.cpp
index ffeb7af..e3968a7 100644
--- a/src/Scanner_IOE.cpp
+++ b/src/Scanner_IOE.cpp
@@ -11,7 +11,7 @@ void Scanner_IOE::init(const uint8_t strobePin)
 */
 void Scanner_IOE::begin()
 {
-    refPortWrite.begin();                       //configures SPI bus
+    refPortWrite.begin();                       //configure SPI bus
     refPortRead.begin(strobeOn);
 }
 
diff --git a/src/Scanner_IOE.h b/src/Scanner_IOE.h
index 27dedda..24b4ab9 100644
--- a/src/Scanner_IOE.h
+++ b/src/Scanner_IOE.h
@@ -8,9 +8,10 @@
 #include <PortReadInterface.h>
 
 /* Scanner_IOE uses bit manipulation to read all pins of one port.
-The ports are normally from an I/O Expander, but could also be ports from an AVR uC.
 The maximum keys per row is 8, because ports have a maximum of 8 pins each.
 
+begin() should be called once from sketch setup().
+
 keybrd_library_developer_guide.md has instructions for ## Active state and diode orientation
 */
 class Scanner_IOE : public ScannerInterface
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 0e19e6d..df4dd1d 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
@@ -32,10 +32,10 @@ Scanner_uC scanner_L(LOW, readPins, readPinCount);
 // =============== RIGHT SCANNER ===============
 const uint8_t PortIOE::DEVICE_ADDR = 0x20;      //MCP23S17 address, all 3 ADDR pins are grounded
 
-PortIOE port_A(0, 0);
+PortIOE port_A(0);
 PortRead_MCP23S17 portRead_A(port_A, 1<<0 | 1<<1 );
 
-PortIOE port_B(1, 0);
+PortIOE port_B(1);
 //PortWrite_MCP23S17 portWrite_B(port_B);     //for LEDs
 PortWrite_MCP23S17 portWrite_B(port_B);
 
@@ -92,5 +92,4 @@ void loop()
     scanDelay.delay();
     //debug.print_scans_per_second();
     //debug.print_microseconds_per_scan();
-delay(100); //todo
 }