move PortWrite_MCP23S17::push() to PortMCP23S17

src/PortMCP23S17.cpp

@@ -0,0 +1,12 @@
+#include "PortMCP23S17.h"
+
+/* push() writes data to registerAddr.
+*/
+void PortMCP23S17::push(const uint8_t command, const uint8_t registerAddr, const uint8_t data)
+{
+    digitalWrite(SS, LOW);                      //enable Slave Select
+      SPI.transfer(command);                    //write command todo also read command?
+      SPI.transfer(registerAddr);               //register address to write data to
+      SPI.transfer(data);                       //write the data
+    digitalWrite(SS, HIGH);                     //disable Slave Select
+}

src/PortMCP23S17.h

@@ -0,0 +1,12 @@
+#ifndef PORTMCP23S17_H
+#define PORTMCP23S17_H
+#include <Arduino.h>
+#include <inttypes.h>
+#include <SPI.h>
+
+class PortMCP23S17
+{
+    protected:
+        void push(const uint8_t command, const uint8_t registerAddr, const uint8_t data);
+};
+#endif

src/PortRead_MCP23S17.cpp

@@ -14,17 +14,9 @@ void PortRead_MCP23S17::begin(const uint8_t strobeOn)
         pullUp = 0;
     }
 
-    digitalWrite(SS, LOW);                      //enable Slave Select
+    push(port.DEVICE_ADDR << 1, port.num, readPins); //write, configure IODIR, 0=output, 1=input
-      SPI.transfer(port.DEVICE_ADDR << 1);      //write command
+    push(port.DEVICE_ADDR << 1, port.num + 0x0C, pullUp); //write, configure GPPU,
-      SPI.transfer(port.num);                   //configure IODIR
+                                                          //0=pull-up disabled, 1=pull-up enabled
-      SPI.transfer(readPins);                   //0=output (for LED), 1=input (for read)
-    digitalWrite(SS, HIGH);                     //enable Slave Select
-
-    digitalWrite(SS, LOW);                      //disable Slave Select
-      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
 }
 
 /* read() returns portState.

src/PortRead_MCP23S17.h

@@ -4,6 +4,7 @@
 #include <inttypes.h>
 #include <SPI.h>
 #include <PortReadInterface.h>
+#include "PortMCP23S17.h"
 #include "PortIOE.h"
 #include "Scanner_IOE.h"
 
@@ -15,7 +16,7 @@ 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)
+    1=configure as input (for read pins connected to column)
     0=configure as output (for LED or not connected to a column)
 readPins are read from pin 0 on up.
 
@@ -32,7 +33,7 @@ MCP23S17 data sheet
  ------------------
  http://www.onsemi.com/pub_link/Collateral/MCP23S17-D.PDF
 */
-class PortRead_MCP23S17 : public PortReadInterface
+class PortRead_MCP23S17 : public PortReadInterface, public PortMCP23S17
 {
     private:
         PortIOE& port;

src/PortWrite_MCP23S17.cpp

@@ -1,16 +1,5 @@
 #include "PortWrite_MCP23S17.h"
 
-/* push() writes data to registerAddr.
-*/
-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);                       //write the data
-    digitalWrite(SS, HIGH);                     //disable Slave Select
-}    
-
 /* begin() is called from Scanner_IOE::begin().
 Initiates SPI bus and configures write pins to output.
 MCP23S17 SPI interface is 10 MHz max.
@@ -23,7 +12,7 @@ void PortWrite_MCP23S17::begin()
     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.
 
-    push(port.num, 0);                          //configure port direction (port.num) to output (0)
+    push(port.DEVICE_ADDR << 1, port.num, 0);   //configure port direction (port.num) to output (0)
 }
 
 /* write() sets pin output to logicLevel.
@@ -42,5 +31,5 @@ void PortWrite_MCP23S17::write(const uint8_t pin, const bool logicLevel)
         port.outputVal |= pin;                  //set pin output to high
     }
 
-    push(port.num + 0x12, port.outputVal);      //set GPIO port pin to outputVal
+    push(port.DEVICE_ADDR << 1, port.num + 0x12, port.outputVal); //set GPIO port pin to outputVal
 }

src/PortWrite_MCP23S17.h

@@ -4,6 +4,7 @@
 #include <inttypes.h>
 #include <SPI.h>
 #include <PortWriteInterface.h>
+#include "PortMCP23S17.h"
 #include "PortIOE.h"
 
 /* One MCP23S17 I/O expander port connected to matrix rows.
@@ -28,11 +29,10 @@ MCP23S17 data sheet
  http://www.onsemi.com/pub_link/Collateral/MCP23S17-D.PDF
 */
 
-class PortWrite_MCP23S17 : public PortWriteInterface
+class PortWrite_MCP23S17 : public PortWriteInterface, public PortMCP23S17
 {
     private:
         PortIOE& port;
-        void push(const uint8_t registerAddr, const uint8_t data);
     public:
         PortWrite_MCP23S17(PortIOE& port) : port(port) {}
         void begin();