diff --git a/doc/keybrd_library_developer_guide.md b/doc/keybrd_library_developer_guide.md
index a5b4cd1..7142f3e 100644
--- a/doc/keybrd_library_developer_guide.md
+++ b/doc/keybrd_library_developer_guide.md
@@ -19,7 +19,6 @@ The keybrd library is flexible for designing custom Rows
 
 this example illustrates the custom Row classes for a fictional keybrd_Ext extension library
 the keybrd_Ext library is for a split keyboard with a matrix on each hand
-other custom Row classes would have a similar structure
 
 Row_Ext::keyWasPressed() overrides RowBase::keyWasPressed()
 Row_Ext::keyWasPressed() is used to unstick sticky keys
@@ -38,8 +37,6 @@ Class inheritance diagram
     Row_Ext_uC  Row_Ext_ShiftRegisters            (inherit Row_Ext::keyWasPressed() )
 
 
-	            RowScannerInterface
-	              /           \
 	RowScanner_PinsArray  RowScanner_SPIShiftRegisters
 
 ```
@@ -70,8 +67,7 @@ Keybrd library class inheritance diagram
 	    /          |             \
 	Row_uC  Row_ShiftRegisters  Row_IOE
 
-	               _____ RowScannerInterface ______
-	              /            |                   \
+
 	RowScanner_PinsArray  RowScanner_PinsBitwise  RowScanner_SPIShiftRegisters
 
 
diff --git a/src/RowScannerInterface.h b/src/RowScannerInterface.h
deleted file mode 100644
index 3d37117..0000000
--- a/src/RowScannerInterface.h
+++ /dev/null
@@ -1,16 +0,0 @@
-#ifndef ROWSCANNERINTERFACE_H
-#define ROWSCANNERINTERFACE_H
-
-#include <Arduino.h>
-#include <inttypes.h>
-#include <config_keybrd.h>
-
-class RowScannerInterface
-{
-    public:
-       // virtual read_pins_t scan(read_pins_mask_t& rowEnd)=0;
-       // todo, remove RowScannerInterface because
-       // some RowScanners will return ColPort e.g. RowScanner_PinsBitwise
-};
-#endif
-
diff --git a/src/RowScanner_PinsArray.h b/src/RowScanner_PinsArray.h
index a54f539..ddb7e04 100644
--- a/src/RowScanner_PinsArray.h
+++ b/src/RowScanner_PinsArray.h
@@ -3,7 +3,6 @@
 #include <Arduino.h>
 #include <inttypes.h>
 #include <config_keybrd.h>
-#include <RowScannerInterface.h>
 #include <RowPort.h>
 #include <ColPort.h>
 
@@ -11,7 +10,7 @@
 The maximum keys per row is 31, because Arduino's largest type is 32 bits and rowEnd consumes the last bit.
 Constructor is in RowScanner_PinsArray.cpp
 */
-class RowScanner_PinsArray : public RowScannerInterface
+class RowScanner_PinsArray
 {
     private:
         static const bool ACTIVE_HIGH;        //logic level of strobe pin: 0=activeLow, 1=activeHigh
diff --git a/src/RowScanner_PinsBitwise.h b/src/RowScanner_PinsBitwise.h
index ec3fc84..23ae99f 100644
--- a/src/RowScanner_PinsBitwise.h
+++ b/src/RowScanner_PinsBitwise.h
@@ -2,14 +2,13 @@
 #define ROWSCANNER_PINSBITWISE_H
 #include <Arduino.h>
 #include <inttypes.h>
-#include <RowScannerInterface.h>
 #include <RowPort.h>
 #include <ColPort.h>
 
 /* RowScanner_PinsBitwise uses bit manipulation to read all pins of one port.
 The maximum keys per row is 8, because ports have a maximum of 8 pins each.
 */
-class RowScanner_PinsBitwise : public RowScannerInterface
+class RowScanner_PinsBitwise
 {
     private:
         RowPort& refRowPort;                //this row's IC port
diff --git a/src/RowScanner_SPIShiftRegisters.h b/src/RowScanner_SPIShiftRegisters.h
index fc031d3..b6e9139 100644
--- a/src/RowScanner_SPIShiftRegisters.h
+++ b/src/RowScanner_SPIShiftRegisters.h
@@ -2,8 +2,8 @@
 #define ROWSCANNER_SPI_SHIFTREGISTERS_H
 #include <Arduino.h>
 #include <inttypes.h>
+#include <config_keybrd.h>
 #include <SPI.h>
-#include <RowScannerInterface.h>
 #include <RowPort.h>
 #include <ColPort.h>
 
@@ -28,7 +28,7 @@ The two parts of a split keyboard can be connected by one of:
  * Ethernet cable (has 8 wires, good for 3 rows)
 
 */
-class RowScanner_SPIShiftRegisters : public RowScannerInterface
+class RowScanner_SPIShiftRegisters
 {
     private:
         static const uint8_t SHIFT_LOAD;        //controller's pin number that is connected to shift register's SHIFT_LOAD pin
diff --git a/src/Row_IOE.h b/src/Row_IOE.h
index f607ff9..440a804 100644
--- a/src/Row_IOE.h
+++ b/src/Row_IOE.h
@@ -39,7 +39,7 @@ class Row_IOE : public RowBase
         Debouncer_4Samples debouncer;
     public:
         Row_IOE( RowPort& refRowPort, const uint8_t strobePin,
-             ColPort& refColPort, Key *const ptrsKeys[], const uint8_t KEY_COUNT)
+             ColPort& refColPort, Key *const ptrsKeys[], const uint8_t KEY_COUNT) //todo if KEY_COUNT is passed in, store it in private
             : RowBase(ptrsKeys), scanner(refRowPort, strobePin, refColPort) { }
         void process();
         uint8_t getRowState(ColPort* ptrColPort, uint8_t& KEY_COUNT);
diff --git a/src/Row_uC.h b/src/Row_uC.h
index 3c2f625..2bc969b 100644
--- a/src/Row_uC.h
+++ b/src/Row_uC.h
@@ -32,9 +32,9 @@ class Row_uC : public RowBase
         RowScanner_PinsArray scanner;
         Debouncer_4Samples debouncer;
     public:
-        Row_uC(const uint8_t strobePin, const uint8_t readPins[], const uint8_t READ_PIN_COUNT,
-                Key *const ptrsKeys[])
-            : RowBase(ptrsKeys), scanner(strobePin, readPins, READ_PIN_COUNT) { }
+        Row_uC(const uint8_t strobePin, const uint8_t readPins[],
+                Key *const ptrsKeys[], const uint8_t KEY_COUNT)
+            : RowBase(ptrsKeys), scanner(strobePin, readPins, KEY_COUNT) { }
         void process();
 };
 #endif