address micros() wrap-around #36

src/BasicStepperDriver.cpp

@@ -113,6 +113,7 @@ void BasicStepperDriver::startMove(long steps){
     } else {
         // set up new move
         dir_state = (steps >= 0) ? HIGH : LOW;
+        last_action_end = 0;
         steps_remaining = abs(steps);
         step_count = 0;
         rest = 0;
@@ -253,9 +254,8 @@ void BasicStepperDriver::calcStepPulse(void){
  * Toggle step and return time until next change is needed (micros)
  */
 long BasicStepperDriver::nextAction(void){
-    long next_action_interval;
     if (steps_remaining > 0){
-        microWaitUntil(next_action_time);
+        delayMicros(next_action_interval, last_action_end);
         /*
          * DIR pin is sampled on rising STEP edge, so it is set first
          */
@@ -267,17 +267,18 @@ long BasicStepperDriver::nextAction(void){
         m = micros() - m;
         // We should pull HIGH for 1-2us (step_high_min)
         if (m < step_high_min){ // fast MCPU or CONSTANT_SPEED
-            DELAY_MICROS(step_high_min-m);
+            delayMicros(step_high_min-m);
             m = step_high_min;
         };
         digitalWrite(step_pin, LOW);
         // account for calcStepPulse() execution time; sets ceiling for max rpm on slower MCUs
+        last_action_end = micros();
         next_action_interval = (pulse > m) ? pulse - m : 1;
     } else {
         // end of move
+        last_action_end = 0;
         next_action_interval = 0;
     }
-    next_action_time = micros() + next_action_interval;
     return next_action_interval;
 }
 

src/BasicStepperDriver.h

@@ -22,14 +22,7 @@
 #define STEP_PULSE(steps, microsteps, rpm) (60*1000000L/steps/microsteps/rpm)
 
 // don't call yield if we have a wait shorter than this
-#define MIN_YIELD_MICROS 25
-inline void microWaitUntil(unsigned long target_micros){
-    if (target_micros - micros() > MIN_YIELD_MICROS){
-        yield();
-    }
-    while (micros() < target_micros);
-}
-#define DELAY_MICROS(us) microWaitUntil(micros() + us)
+#define MIN_YIELD_MICROS 50
 
 /*
  * Basic Stepper Driver class.
@@ -40,10 +33,24 @@ class BasicStepperDriver {
     enum Mode {CONSTANT_SPEED, LINEAR_SPEED};
     enum State {STOPPED, ACCELERATING, CRUISING, DECELERATING};
 
+    static inline void delayMicros(unsigned long delay_us, unsigned long start_us = 0){
+        if (delay_us){
+            if (!start_us){
+                start_us = micros();
+            }
+            if (delay_us > MIN_YIELD_MICROS){
+                yield();
+            }
+            // See https://www.gammon.com.au/millis
+            while (micros() - start_us < delay_us);
+        }
+    }
+
 private:
     // calculation remainder to be fed into successive steps to increase accuracy (Atmel DOC8017)
     long rest;
-    unsigned long next_action_time = 0;
+    unsigned long last_action_end = 0;
+    unsigned long next_action_interval = 0;
 
 protected:
     /*

src/MultiDriver.cpp

@@ -27,15 +27,14 @@ void MultiDriver::startMove(long steps1, long steps2, long steps3){
         }
     );
     ready = false;
+    last_action_end = 0;
 }
 /*
  * Trigger next step action
  */
 long MultiDriver::nextAction(void){
-    static unsigned long next_action_time = 0;
-    long next_action_interval = 0;
-
-    microWaitUntil(next_action_time);
+    Motor::delayMicros(next_action_interval, last_action_end);
+    next_action_interval = 0;
 
     // Trigger all the motors that need it (event timer = 0)
     FOREACH_MOTOR(
@@ -60,7 +59,7 @@ long MultiDriver::nextAction(void){
             event_timers[i] -= next_action_interval;
         }
     );
-    next_action_time = micros() + next_action_interval;
+    last_action_end = 0;
     return next_action_interval;
 }
 /*

src/MultiDriver.h

@@ -37,6 +37,8 @@ class MultiDriver {
     bool ready = true;
     // when next state change is due for each motor
     long event_timers[MAX_MOTORS];
+    unsigned long next_action_interval = 0;
+    unsigned long last_action_end = 0;
 
 public:
     /*