diff --git a/src/PortInterface.h b/src/PortInterface.h
index 0f37b1f..5295b92 100644
--- a/src/PortInterface.h
+++ b/src/PortInterface.h
@@ -9,13 +9,15 @@ Port classes are the keybrd library's interface to microcontroller ports or I/O
 
 Port classes that can read and write, inherit from PortInterface.
 Port classes that can only write, inherit from PortWriteInterface.
+
+write() interface emulates Arduino's digitalWrite().
 */
 class PortInterface : public PortWriteInterface
 {
     public:
         virtual void beginProtocol()=0;               //SPI bus or I2C bus
         virtual void begin(const uint8_t strobeOn)=0; //configure GPIO pins
-        virtual void write(const uint8_t strobePin, const bool pinLogicLevel)=0;
+        virtual void write(const uint8_t pin, const bool pinLogicLevel)=0;
         virtual uint8_t read()=0;
 };
 #endif
diff --git a/src/PortWriteInterface.h b/src/PortWriteInterface.h
index b7e3815..98ee81c 100644
--- a/src/PortWriteInterface.h
+++ b/src/PortWriteInterface.h
@@ -8,6 +8,8 @@ Port classes are the keybrd library's interface to MOSI shift registers i.e. Por
 
 Port classes that can read & write, inherit from PortInterface.
 Port classes that can only write, inherit from PortWriteInterface.
+
+write() interface emulates Arduino's digitalWrite().
 */
 class PortWriteInterface
 {
diff --git a/src/Scanner_ShiftRegsReadStrobed.cpp b/src/Scanner_ShiftRegsReadStrobed.cpp
index 7f7d505..c58915f 100644
--- a/src/Scanner_ShiftRegsReadStrobed.cpp
+++ b/src/Scanner_ShiftRegsReadStrobed.cpp
@@ -48,7 +48,8 @@ read_pins_t Scanner_ShiftRegsReadStrobed::scan(const uint8_t strobePin)
 
     //SPI.beginTransaction( SPISettings(5000000, MSBFIRST, SPI_MODE0) ); //control SPI bus, 5 MHz
 
-    delayMicroseconds(20);                      //photo-transistor at 3.3v needs 20 ms to stablize
+                                                //photo-transistor at 3.3v needs 20 ms to stabilize
+    delayMicroseconds(20);                      //monitor trackball here
 
     digitalWrite(slaveSelect, HIGH);            //shift the data toward a serial output