diff --git a/src/RowScanner_SPIShiftRegisters.cpp b/src/RowScanner_SPIShiftRegisters.cpp
index bfa1cf8..9379a39 100644
--- a/src/RowScanner_SPIShiftRegisters.cpp
+++ b/src/RowScanner_SPIShiftRegisters.cpp
@@ -2,8 +2,12 @@
 
 void RowScanner_SPIShiftRegisters::begin()
 {
-    pinMode (SS, OUTPUT);
-    digitalWrite (SS, HIGH);
+    //configure row
+    pinMode(STROBE_PIN, OUTPUT);
+
+    //todo there is only one slave, is select needed?
+    pinMode (SHIFT_LOAD, OUTPUT);
+    digitalWrite (SHIFT_LOAD, HIGH);
 }
 
 /*
@@ -11,12 +15,20 @@ Sets rowEnd and returns rowState.
 */
 read_pins_t RowScanner_SPIShiftRegisters::scan(read_pins_mask_t& rowEnd)
 {
-//todo rowEnd, rowState, return int size depend on BYTE_COUNT, like in send(), set in config_keybrd?
     read_pins_t rowState = 0;
 
-    digitalWrite(SS, LOW);                      //load parallel inputs to the register
-    digitalWrite(SS, HIGH);                     //shift the data toward a serial output
+    //strobe row on
+    digitalWrite(STROBE_PIN, LOW);
+    delayMicroseconds(3);                       //time to stablize voltage
+
+    //read all the column pins
+    digitalWrite(SHIFT_LOAD, LOW);                      //load parallel inputs to the register
+    digitalWrite(SHIFT_LOAD, HIGH);                     //shift the data toward a serial output
     SPI.transfer(&rowState, BYTE_COUNT);
+
+    //strobe row off
+    digitalWrite(STROBE_PIN, HIGH);
+
     rowEnd = 1 << KEY_COUNT;
     return rowState;
 }
diff --git a/src/RowScanner_SPIShiftRegisters.h b/src/RowScanner_SPIShiftRegisters.h
index d8f0028..fd045e9 100644
--- a/src/RowScanner_SPIShiftRegisters.h
+++ b/src/RowScanner_SPIShiftRegisters.h
@@ -14,12 +14,16 @@ The maximum keys per row is 31, because Arduino's largest type is 32 bits and ro
 class RowScanner_SPIShiftRegisters : public RowScannerInterface
 {
     private:
-        const uint8_t SS;                       //pin on master that selects slave
+        //todo static const bool ACTIVE_HIGH;          //logic level of strobe pin: 0=activeLow, 1=activeHigh
+        const uint8_t STROBE_PIN;               //Arduino pin number connected to this row
+        const uint8_t SHIFT_LOAD;               //controller's pin number that is connected to shift register's SHIFT_LOAD pin
         const uint8_t BYTE_COUNT;               //number of bytes to read from shift registers
         const uint8_t KEY_COUNT;                //number of keys in row
     public:
-        RowScanner_SPIShiftRegisters(const uint8_t SS, uint8_t BYTE_COUNT, uint8_t KEY_COUNT)
-            : SS(SS), BYTE_COUNT(BYTE_COUNT), KEY_COUNT(KEY_COUNT) {}
+        RowScanner_SPIShiftRegisters(const uint8_t STROBE_PIN, const uint8_t SHIFT_LOAD,
+                uint8_t BYTE_COUNT, uint8_t KEY_COUNT)
+            : STROBE_PIN(STROBE_PIN), SHIFT_LOAD(SHIFT_LOAD),
+                BYTE_COUNT(BYTE_COUNT), KEY_COUNT(KEY_COUNT) {}
         virtual read_pins_t scan(read_pins_mask_t& rowEnd);
         void begin();
 };
diff --git a/src/Row_ShiftRegisters.h b/src/Row_ShiftRegisters.h
index 777e1e7..cf244ad 100644
--- a/src/Row_ShiftRegisters.h
+++ b/src/Row_ShiftRegisters.h
@@ -4,6 +4,7 @@
 #include <RowBase.h>
 #include <RowScanner_SPIShiftRegisters.h>
 #include <Debouncer_4Samples.h>
+//todo #include <Debouncer_Not.h>
 
 /* Row_DH_IOE is a row connected to an Input/Output Expander.
 
@@ -28,9 +29,11 @@ class Row_ShiftRegisters : public RowBase
     private:
         RowScanner_SPIShiftRegisters scanner;
         Debouncer_4Samples debouncer;
+        //Debouncer_Not debouncer; //todo test
     public:
-        Row_ShiftRegisters(const uint8_t SS, uint8_t BYTE_COUNT, Key *const ptrsKeys[], uint8_t KEY_COUNT)
-            : RowBase(ptrsKeys), scanner(SS, BYTE_COUNT, KEY_COUNT) { }
+        Row_ShiftRegisters(const uint8_t STROBE_PIN, const uint8_t SHIFT_LOAD, uint8_t BYTE_COUNT,
+                Key *const ptrsKeys[], uint8_t KEY_COUNT)
+            : RowBase(ptrsKeys), scanner(STROBE_PIN, SHIFT_LOAD, BYTE_COUNT, KEY_COUNT) { }
         void begin();
         read_pins_t scan(read_pins_mask_t& rowEnd);
         read_pins_t debounce(const read_pins_t rowState, read_pins_t& debounced);