change RowScanner_SPIShiftRegisters to work with active high or active low

examples/keybrd_shift_register/keybrd_shift_register.ino

@@ -37,6 +37,10 @@ const bool RowScanner_PinsArray::STROBE_OFF = HIGH;
 
 const uint8_t RowScanner_SPIShiftRegisters::SHIFT_LOAD = 10;
 
+//active state of right matrix
+const bool RowScanner_SPIShiftRegisters::STROBE_ON = LOW;
+const bool RowScanner_SPIShiftRegisters::STROBE_OFF = HIGH;
+
 Debug debug;
 
 // ================= LEFT PINS =================
@@ -144,7 +148,7 @@ Key* ptrsKeys_R0[] = { &s_0, &s_z, &s_z, &s_z, &s_1, &s_z, &s_z, &s_z,
                        &s_4, &s_z, &s_z, &s_z, &s_5, &s_z, &s_z, &s_z,
                        &s_6, &s_z, &s_z, &s_z, &s_3, &s_4, &s_5, &s_6 };
 const uint8_t KEY_R0_COUNT = sizeof(ptrsKeys_R0)/sizeof(*ptrsKeys_R0);
-Row_ShiftRegisters row_R0(8, ptrsKeys_R0, KEY_R0_COUNT);
+Row_ShiftRegisters row_R0(0, ptrsKeys_R0, KEY_R0_COUNT);
 
 //prints a b c d u v w x
 Key* ptrsKeys_R1[] = { &s_a, &s_z, &s_z, &s_z, &s_b, &s_z, &s_z, &s_z,
@@ -152,7 +156,7 @@ Key* ptrsKeys_R1[] = { &s_a, &s_z, &s_z, &s_z, &s_b, &s_z, &s_z, &s_z,
                        &s_e, &s_z, &s_z, &s_z, &s_f, &s_z, &s_z, &s_z,
                        &s_g, &s_z, &s_z, &s_z, &s_u, &s_v, &s_w, &s_x };
 const uint8_t KEY_R1_COUNT = sizeof(ptrsKeys_R1)/sizeof(*ptrsKeys_R1);
-Row_ShiftRegisters row_R1(9, ptrsKeys_R1, KEY_R1_COUNT);
+Row_ShiftRegisters row_R1(1, ptrsKeys_R1, KEY_R1_COUNT);
 
 // ################### MAIN ####################
 void setup()

src/RowScanner_PinsArray.h

@@ -13,7 +13,7 @@ class RowScanner_PinsArray
 {
     private:
         static const bool STROBE_ON;            //logic level of strobe on, HIGH or LOW
-        static const bool STROBE_OFF;         //logic level of strobe off, HIGH or LOW
+        static const bool STROBE_OFF;           //logic level of strobe off, complement of STROBE_ON
         const uint8_t STROBE_PIN;               //Arduino pin number connected to this row
         const uint8_t* const READ_PINS;         //array of read pin numbers
         const uint8_t READ_PIN_COUNT;           //number of read pins

src/RowScanner_SPIShiftRegisters.cpp

@@ -23,7 +23,7 @@ read_pins_t RowScanner_SPIShiftRegisters::scan(uint8_t& keyCount)
     read_pins_t rowState = 0;
 
     //strobe row on
-    digitalWrite(STROBE_PIN, HIGH);
+    digitalWrite(STROBE_PIN, STROBE_ON);
     delayMicroseconds(3);                       //time to stablize voltage
 
     //read all the column pins
@@ -32,7 +32,7 @@ read_pins_t RowScanner_SPIShiftRegisters::scan(uint8_t& keyCount)
     SPI.transfer(&rowState, BYTE_COUNT);
 
     //strobe row off
-    digitalWrite(STROBE_PIN, LOW);
+    digitalWrite(STROBE_PIN, STROBE_OFF);
 
     keyCount = KEY_COUNT;
 

src/RowScanner_SPIShiftRegisters.h

@@ -8,20 +8,29 @@
 #include <ColPort.h>
 
 /* RowScanner_SPIShiftRegisters reads shift registers.
-shift registers 74HC165 Parallel-In-Serial-Out (PISO)
+shift registers 74HC165 is Parallel-In-Serial-Out (PISO)
+Upto 4 shift registers can be in a daisy chained.
 
-in sketch:
+In sketch:
     const uint8_t RowScanner_SPIShiftRegisters::SHIFT_LOAD = 10;
     call begin() from setup()
 
-Upto 4 shift registers can be in a daisy chained.
+For active low:
+    const bool RowScanner_SPIShiftRegisters::STROBE_ON = LOW;
+    const bool RowScanner_SPIShiftRegisters::STROBE_OFF = HIGH;
+    //shift register parallel input pins have 10k pull-down resistors powered
+    //controller's MISO pin is connected to shift register's complementary serial output (/QH) pin
 
-The shift registers are active high:
+For active high:
-    10k pull-down resistors are grounded
+    const bool RowScanner_SPIShiftRegisters::STROBE_ON = HIGH;
-    connect controller's MISO pin to shift register's QH pin
+    const bool RowScanner_SPIShiftRegisters::STROBE_OFF = LOW;
+    //shift register parallel input pins have 10k pull-down resistors grounded
+    //controller's MISO pin is connected to shift register's serial output (QH) pin
 
-The shift register needs 5 wires.
 In addition, each row needs to be connected to a strobe pin from controller.
+
+ todo move this to tutorial
+The shift register needs 5 wires.
 The two parts of a split keyboard can be connected by one of:
  * eSATA cable (has 7 wires, good for 2 rows)
  * Ethernet cable (has 8 wires, good for 3 rows)
@@ -31,6 +40,8 @@ class RowScanner_SPIShiftRegisters
 {
     private:
         static const uint8_t SHIFT_LOAD;        //controller's pin number that is connected to shift register's SHIFT_LOAD pin
+        static const bool STROBE_ON;            //logic level of strobe on, active state HIGH or LOW
+        static const bool STROBE_OFF;           //logic level of strobe off, complement of active state
         const uint8_t STROBE_PIN;               //Arduino pin number connected to this row
         const uint8_t BYTE_COUNT;               //number of bytes to read from shift registers
         uint8_t KEY_COUNT;