Simplify Stepper::stepMotor()

Instead of separately coding each step, use the fact that all pins
follow the same periodic pattern, with phase shifts between them.

For the 5-pin steppers, hard-code the pattern in a PROGMEM array, as
this is cheaper than reducing a number modulo 10 on chips lacking a
hardware divider.

Author: edgar-bonet

src/Stepper.cpp

@@ -233,128 +233,29 @@ void Stepper::step(int steps_to_move)
  */
 void Stepper::stepMotor(int thisStep)
 {
-  if (this->pin_count == 2) {
-    switch (thisStep) {
-      case 0:  // 01
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, HIGH);
-      break;
-      case 1:  // 11
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, HIGH);
-      break;
-      case 2:  // 10
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, LOW);
-      break;
-      case 3:  // 00
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, LOW);
-      break;
-    }
-  }
-  if (this->pin_count == 4) {
-    switch (thisStep) {
-      case 0:  // 1010
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, LOW);
-        digitalWrite(motor_pin_3, HIGH);
-        digitalWrite(motor_pin_4, LOW);
-      break;
-      case 1:  // 0110
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, HIGH);
-        digitalWrite(motor_pin_3, HIGH);
-        digitalWrite(motor_pin_4, LOW);
-      break;
-      case 2:  //0101
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, HIGH);
-        digitalWrite(motor_pin_3, LOW);
-        digitalWrite(motor_pin_4, HIGH);
-      break;
-      case 3:  //1001
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, LOW);
-        digitalWrite(motor_pin_3, LOW);
-        digitalWrite(motor_pin_4, HIGH);
-      break;
-    }
-  }
+  static PROGMEM const uint8_t phases[] = {
+    LOW, LOW, LOW, LOW, HIGH, HIGH, HIGH, HIGH, HIGH,
+    LOW, LOW, LOW, LOW, LOW, HIGH, HIGH, HIGH, HIGH
+  };
 
-  if (this->pin_count == 5) {
-    switch (thisStep) {
-      case 0:  // 01101
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, HIGH);
-        digitalWrite(motor_pin_3, HIGH);
-        digitalWrite(motor_pin_4, LOW);
-        digitalWrite(motor_pin_5, HIGH);
-        break;
-      case 1:  // 01001
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, HIGH);
-        digitalWrite(motor_pin_3, LOW);
-        digitalWrite(motor_pin_4, LOW);
-        digitalWrite(motor_pin_5, HIGH);
-        break;
-      case 2:  // 01011
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, HIGH);
-        digitalWrite(motor_pin_3, LOW);
-        digitalWrite(motor_pin_4, HIGH);
-        digitalWrite(motor_pin_5, HIGH);
-        break;
-      case 3:  // 01010
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, HIGH);
-        digitalWrite(motor_pin_3, LOW);
-        digitalWrite(motor_pin_4, HIGH);
-        digitalWrite(motor_pin_5, LOW);
-        break;
-      case 4:  // 11010
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, HIGH);
-        digitalWrite(motor_pin_3, LOW);
-        digitalWrite(motor_pin_4, HIGH);
-        digitalWrite(motor_pin_5, LOW);
-        break;
-      case 5:  // 10010
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, LOW);
-        digitalWrite(motor_pin_3, LOW);
-        digitalWrite(motor_pin_4, HIGH);
-        digitalWrite(motor_pin_5, LOW);
-        break;
-      case 6:  // 10110
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, LOW);
-        digitalWrite(motor_pin_3, HIGH);
-        digitalWrite(motor_pin_4, HIGH);
-        digitalWrite(motor_pin_5, LOW);
-        break;
-      case 7:  // 10100
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, LOW);
-        digitalWrite(motor_pin_3, HIGH);
-        digitalWrite(motor_pin_4, LOW);
-        digitalWrite(motor_pin_5, LOW);
-        break;
-      case 8:  // 10101
-        digitalWrite(motor_pin_1, HIGH);
-        digitalWrite(motor_pin_2, LOW);
-        digitalWrite(motor_pin_3, HIGH);
-        digitalWrite(motor_pin_4, LOW);
-        digitalWrite(motor_pin_5, HIGH);
-        break;
-      case 9:  // 00101
-        digitalWrite(motor_pin_1, LOW);
-        digitalWrite(motor_pin_2, LOW);
-        digitalWrite(motor_pin_3, HIGH);
-        digitalWrite(motor_pin_4, LOW);
-        digitalWrite(motor_pin_5, HIGH);
-        break;
-    }
+  switch (pin_count) {
+    case 2:
+      digitalWrite(motor_pin_1, (thisStep+1) & 2);
+      digitalWrite(motor_pin_2, (thisStep+2) & 2);
+    break;
+    case 4:
+      digitalWrite(motor_pin_4, (thisStep+0) & 2);
+      digitalWrite(motor_pin_2, (thisStep+1) & 2);
+      digitalWrite(motor_pin_3, (thisStep+2) & 2);
+      digitalWrite(motor_pin_1, (thisStep+3) & 2);
+    break;
+    case 5:
+      digitalWrite(motor_pin_1, pgm_read_byte(&phases[thisStep+0]));
+      digitalWrite(motor_pin_4, pgm_read_byte(&phases[thisStep+2]));
+      digitalWrite(motor_pin_2, pgm_read_byte(&phases[thisStep+4]));
+      digitalWrite(motor_pin_5, pgm_read_byte(&phases[thisStep+6]));
+      digitalWrite(motor_pin_3, pgm_read_byte(&phases[thisStep+8]));
+    break;
   }
 }