rename PortWrite_MCP23S17::push() to transfer()

src/PortMCP23S17.cpp

@@ -1,12 +1,16 @@
 #include "PortMCP23S17.h"
 
-/* push() writes data to registerAddr.
+/* transfer() writes data to registerAddr, reads portSate from registerAddr, and returns portState.
 */
-void PortMCP23S17::push(const uint8_t command, const uint8_t registerAddr, const uint8_t data)
+uint8_t PortMCP23S17::transfer(const uint8_t command, const uint8_t registerAddr, const uint8_t data)
 {
+    uint8_t portState;                          //bit wise
+
     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
+      portState = SPI.transfer(data);           //write data, read portState
     digitalWrite(SS, HIGH);                     //disable Slave Select
+
+    return portState;
 }

src/PortMCP23S17.h

@@ -7,6 +7,6 @@
 class PortMCP23S17
 {
     protected:
-        void push(const uint8_t command, const uint8_t registerAddr, const uint8_t data);
+        uint8_t transfer(const uint8_t command, const uint8_t registerAddr, const uint8_t data);
 };
 #endif

src/PortRead_MCP23S17.cpp

@@ -14,8 +14,8 @@ void PortRead_MCP23S17::begin(const uint8_t strobeOn)
         pullUp = 0;
     }
 
-    push(port.DEVICE_ADDR << 1, port.num, readPins); //write, configure IODIR, 0=output, 1=input
-    push(port.DEVICE_ADDR << 1, port.num + 0x0C, pullUp); //write, configure GPPU,
+    transfer(port.DEVICE_ADDR << 1, port.num, readPins); //write, configure IODIR, 0=output, 1=input
+    transfer(port.DEVICE_ADDR << 1, port.num + 0x0C, pullUp); //write, configure GPPU,
                                                           //0=pull-up disabled, 1=pull-up enabled
 }
 
@@ -24,13 +24,5 @@ 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.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
-
-    return portState;
+    return transfer( (port.DEVICE_ADDR << 1) | 1, port.num + 0x12, 0); //read from GPIO
 }

src/PortWrite_MCP23S17.cpp

@@ -12,7 +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.DEVICE_ADDR << 1, port.num, 0);   //configure port direction (port.num) to output (0)
+    transfer(port.DEVICE_ADDR << 1, port.num, 0); //configure port direction (port.num) to output (0)
 }
 
 /* write() sets pin output to logicLevel.
@@ -31,5 +31,5 @@ void PortWrite_MCP23S17::write(const uint8_t pin, const bool logicLevel)
         port.outputVal |= pin;                  //set pin output to high
     }
 
-    push(port.DEVICE_ADDR << 1, port.num + 0x12, port.outputVal); //set GPIO port pin to outputVal
+    transfer(port.DEVICE_ADDR << 1, port.num + 0x12, port.outputVal); //set GPIO port to outputVal
 }