PROGMEM approach

This version saves 28 bytes of dynamic memory in library code by using
PROGMEM for driver patterns.
File stepper_oneRevolution_28BYJ48_ULN2003.ino shows, how to use PROGMEM
also for patterns of custom drivers.

libraries/Stepper/examples/stepper_oneRevolution_28BYJ48_ULN2003/stepper_oneRevolution_28BYJ48_ULN2003.ino

@@ -35,7 +35,7 @@ const int stepsPerRevolution = 4096;  // change this to fit the number of steps
  *    7  1  0  0  0
  *    8  1  0  0  1
  */
-const unsigned char phasesMatrix[8]= {
+const unsigned char phasesMatrix[8] PROGMEM = {
   0b00010000,
   0b00110000,
   0b00100000,

libraries/Stepper/src/Stepper.cpp

@@ -188,11 +188,12 @@ void Stepper::step(int steps_to_move)
 /*
  * Moves the motor forward or backwards.
  */
-void Stepper::stepMotor(int thisStep)
+void Stepper::stepMotor(int thisPhase)
 {
+  unsigned char phase = pgm_read_byte_near(phasesMatrix + thisPhase);
   unsigned char running_one = 0b10000000;
   for (int i = 0; i < pin_count; i++, running_one >>= 1){
-    digitalWrite(motor_pin[i], (phasesMatrix[thisStep] & running_one));
+    digitalWrite(motor_pin[i], (phase & running_one));
   }
 }
 

libraries/Stepper/src/Stepper.h

@@ -85,6 +85,38 @@
 #ifndef Stepper_h
 #define Stepper_h
 
+#include <avr/pgmspace.h>
+
+    //Default phases matrix for 2 control wires is as follows
+    const unsigned char phasesMatrix2[4]  PROGMEM = {
+      0b01000000,
+      0b11000000,
+      0b10000000,
+      0b00000000
+    };
+
+    //Default phases matrix for 4 control wires is as follows
+    const unsigned char phasesMatrix4[4]  PROGMEM = {
+      0b10100000,
+      0b01100000,
+      0b01010000,
+      0b10010000
+    };
+
+    //Default phases matrix for 5 control wires is as follows
+    const unsigned char phasesMatrix5[10] PROGMEM = {
+      0b01101000,
+      0b01001000,
+      0b01011000,
+      0b01010000,
+      0b11010000,
+      0b10010000,
+      0b10110000,
+      0b10100000,
+      0b10101000,
+      0b00101000
+    };
+
 // library interface description
 class Stepper {
   public:
@@ -109,7 +141,7 @@ class Stepper {
     int version(void);
 
   private:
-    void stepMotor(int this_step);
+    void stepMotor(int thisPhase);
     void initMotor(int number_of_steps, int motor_pin_1, int motor_pin_2,
                                         int motor_pin_3, int motor_pin_4,
                                         int motor_pin_5, unsigned char *phasesMatrix,
@@ -124,36 +156,6 @@ class Stepper {
 
     // motor pin numbers:
     int motor_pin[5];         // Maximum 5 control signals
-
-    //Default phases matrix for 2 control wires is as follows
-    const unsigned char phasesMatrix2[4]  = {
-      0b01000000,
-      0b11000000,
-      0b10000000,
-      0b00000000
-    };
-
-    //Default phases matrix for 4 control wires is as follows
-    const unsigned char phasesMatrix4[4]  = {
-      0b10100000,
-      0b01100000,
-      0b01010000,
-      0b10010000
-    };
-
-    //Default phases matrix for 5 control wires is as follows
-    const unsigned char phasesMatrix5[10] = {
-      0b01101000,
-      0b01001000,
-      0b01011000,
-      0b01010000,
-      0b11010000,
-      0b10010000,
-      0b10110000,
-      0b10100000,
-      0b10101000,
-      0b00101000
-    };
 };
 
 #endif