nextAction() now waits until the right time

This makes the code less non-blocking but simplifies what the caller has to do while still allowing control to pass back to the caller for each step.

examples/AccelTest/AccelTest.ino

@@ -45,7 +45,6 @@ void loop() {
         Serial.print("  dt="); Serial.print(wait_time);
         Serial.print("  rpm="); Serial.print(stepper.getCurrentRPM());
         Serial.println();
-        microWaitUntil(micros() + wait_time);
     } else {
         stepper.disable();
         Serial.println("END");

library.properties

@@ -1,9 +1,9 @@
 name=StepperDriver
-version=1.1.2-beta
+version=1.1.2-beta2
 author=Laurentiu Badea
 maintainer=Laurentiu Badea
 sentence=A4988, DRV8825 and generic two-pin stepper motor driver library.
-paragraph=Control steppers via a driver board providing STEP+DIR. Microstepping is supported. Acceleration is supported. Supported drivers are A4988, DRV8824, DRV8825, DRV8834, DRV8880.
+paragraph=Control steppers via a driver board providing STEP+DIR like the ones from Pololu. Microstepping is supported. Acceleration is supported. Supported drivers are A4988, DRV8824, DRV8825, DRV8834, DRV8880.
 category=Device Control
 url=https://github.com/laurb9/StepperDriver
 architectures=*

src/BasicStepperDriver.cpp

@@ -85,12 +85,8 @@ void BasicStepperDriver::setSpeedProfile(Mode mode, short accel, short decel){
  * positive to move forward, negative to reverse
  */
 void BasicStepperDriver::move(long steps){
-    long next_event;
     startMove(steps);
-    do {
-        next_event = nextAction();
-        microWaitUntil(micros() + next_event);
-    } while (next_event);
+    while (nextAction());
 }
 /*
  * Move the motor a given number of degrees (1-360)
@@ -252,10 +248,14 @@ void BasicStepperDriver::calcStepPulse(void){
     }
 }
 /*
+ * Yield to step control
  * Toggle step and return time until next change is needed (micros)
  */
 long BasicStepperDriver::nextAction(void){
+    static unsigned long next_action_time = 0;
+    long next_action_interval = 0;
     if (steps_remaining > 0){
+        microWaitUntil(next_action_time);
         /*
          * DIR pin is sampled on rising STEP edge, so it is set first
          */
@@ -272,10 +272,13 @@ long BasicStepperDriver::nextAction(void){
         };
         digitalWrite(step_pin, LOW);
         // account for calcStepPulse() execution time
-        return pulse - m;
+        next_action_interval = pulse - m;
     } else {
-        return 0; // end of move
+        // end of move
+        next_action_interval = 0;
     }
+    next_action_time = micros() + next_action_interval;
+    return next_action_interval;
 }
 enum BasicStepperDriver::State BasicStepperDriver::getCurrentState(void){
     enum State state;

src/BasicStepperDriver.h

@@ -144,7 +144,7 @@ class BasicStepperDriver {
      * Methods for non-blocking mode.
      * They use more code but allow doing other operations between impulses.
      * The flow has two parts - start/initiate followed by looping with nextAction.
-     * See AccelTest example.
+     * See NonBlocking example.
      */
     /*
      * Initiate a move over known distance (calculate and save the parameters)
@@ -157,7 +157,7 @@ class BasicStepperDriver {
     void startRotate(long deg);
     void startRotate(double deg);
     /*
-     * Toggle step and return time until next change is needed (micros)
+     * Toggle step at the right time and return time until next change is needed (micros)
      */
     long nextAction(void);
     /*

src/MultiDriver.cpp

@@ -32,6 +32,11 @@ void MultiDriver::startMove(long steps1, long steps2, long steps3){
  * Trigger next step action
  */
 long MultiDriver::nextAction(void){
+    static unsigned long next_action_time = 0;
+    long next_action_interval = 0;
+
+    microWaitUntil(next_action_time);
+
     // Trigger all the motors that need it (event timer = 0)
     FOREACH_MOTOR(
         if (event_timers[i] == 0){
@@ -40,23 +45,23 @@ long MultiDriver::nextAction(void){
     );
     // Find the time when the next pulse needs to fire
     // this is the smallest non-zero timer value from all active motors
-    long next_event = 0;
     ready = true;
     FOREACH_MOTOR(
         if (event_timers[i] > 0){
             ready = false;
-            if (event_timers[i] < next_event || next_event == 0){
-                next_event = event_timers[i];
+            if (event_timers[i] < next_action_interval || next_action_interval == 0){
+                next_action_interval = event_timers[i];
             }
         }
     );
     // Reduce all event timers by the current left time so 0 marks next
     FOREACH_MOTOR(
         if (event_timers[i] > 0){
-            event_timers[i] -= next_event;
+            event_timers[i] -= next_action_interval;
         }
     );
-    return (ready) ? 0 : next_event;
+    next_action_time = micros() + next_action_interval;
+    return next_action_interval;
 }
 /*
  * Optionally, call this to begin braking to stop early
@@ -91,8 +96,6 @@ void MultiDriver::move(long steps1, long steps2, long steps3){
     startMove(steps1, steps2, steps3);
     while (!ready){
         next_event = nextAction();
-        // wait until the next event
-        microWaitUntil(micros() + next_event);
     }
 }