Enable per motor fix (#771)

* - moved invert option in front of per motor enables.

* Added code to prevent motors_set_disable() from setting values that already exist.

* Added the enable delay from PR 720

* Adding a defined default for step enable delay

* Fixing feed rates with kinematics and arcs.

- Kinematics changes the feed rate and the loop that creates arc was re-using the altered rate. This caused a runaway situation.

Grbl_Esp32/src/Defaults.h

@@ -42,6 +42,10 @@
 #    define DEFAULT_STEP_PULSE_MICROSECONDS 3  // $0
 #endif
 
+#ifndef DEFAULT_STEP_ENABLE_DELAY
+#    define DEFAULT_STEP_ENABLE_DELAY 0
+#endif
+
 #ifndef DEFAULT_STEPPER_IDLE_LOCK_TIME
 #    define DEFAULT_STEPPER_IDLE_LOCK_TIME 250  // $1 msec (0-254, 255 keeps steppers enabled)
 #endif

Grbl_Esp32/src/MotionControl.cpp

@@ -184,8 +184,9 @@ void mc_arc(float*            target,
         float    cos_Ti;
         float    r_axisi;
         uint16_t i;
-        uint8_t  count = 0;
-        for (i = 1; i < segments; i++) {  // Increment (segments-1).
+        uint8_t  count             = 0;
+        float    original_feedrate = pl_data->feed_rate;  // Kinematics may alter the feedrate, so save an original copy
+        for (i = 1; i < segments; i++) {                  // Increment (segments-1).
             if (count < N_ARC_CORRECTION) {
                 // Apply vector rotation matrix. ~40 usec
                 r_axisi = r_axis0 * sin_T + r_axis1 * cos_T;
@@ -206,6 +207,7 @@ void mc_arc(float*            target,
             position[axis_1] = center_axis1 + r_axis1;
             position[axis_linear] += linear_per_segment;
 #ifdef USE_KINEMATICS
+            pl_data->feed_rate = original_feedrate;  // This restores the feedrate kinematics may have altered
             mc_line_kins(position, pl_data, previous_position);
             previous_position[axis_0]      = position[axis_0];
             previous_position[axis_1]      = position[axis_1];

Grbl_Esp32/src/Motors/Motors.cpp

@@ -413,7 +413,19 @@ void           init_motors() {
 }
 
 void motors_set_disable(bool disable, uint8_t mask) {
-    static bool previous_state = true;
+    static bool    prev_disable = true;
+    static uint8_t prev_mask    = 0;
+
+    if ((disable == prev_disable) && (mask == prev_mask)) {
+        return;
+    }
+
+    prev_disable = disable;
+    prev_mask    = mask;
+
+    if (step_enable_invert->get()) {
+        disable = !disable;  // Apply pin invert.
+    }
 
     // now loop through all the motors to see if they can individually disable
     auto n_axis = number_axis->get();
@@ -425,11 +437,19 @@ void motors_set_disable(bool disable, uint8_t mask) {
         }
     }
 
-    // invert only inverts the global stepper disable pin.
-    if (step_enable_invert->get()) {
-        disable = !disable;  // Apply pin invert.
-    }
+    // global disable.
     digitalWrite(STEPPERS_DISABLE_PIN, disable);
+
+    // Add an optional delay for stepper drivers. that need time
+    // Some need time after the enable before they can step.
+    auto wait_disable_change = enable_delay_microseconds->get();
+    if (wait_disable_change != 0) {
+        auto disable_start_time = esp_timer_get_time() + wait_disable_change;
+
+        while ((esp_timer_get_time() - disable_start_time) < 0) {
+            NOP();
+        }
+    }
 }
 
 void motors_read_settings() {

Grbl_Esp32/src/SettingsDefinitions.cpp

@@ -10,6 +10,7 @@ StringSetting* build_info;
 
 IntSetting* pulse_microseconds;
 IntSetting* stepper_idle_lock_time;
+IntSetting* enable_delay_microseconds;
 
 AxisMaskSetting* step_invert_mask;
 AxisMaskSetting* dir_invert_mask;
@@ -399,6 +400,7 @@ void make_settings() {
     step_invert_mask       = new AxisMaskSetting(GRBL, WG, "2", "Stepper/StepInvert", DEFAULT_STEPPING_INVERT_MASK, postMotorSetting);
     stepper_idle_lock_time = new IntSetting(GRBL, WG, "1", "Stepper/IdleTime", DEFAULT_STEPPER_IDLE_LOCK_TIME, 0, 255);
     pulse_microseconds     = new IntSetting(GRBL, WG, "0", "Stepper/Pulse", DEFAULT_STEP_PULSE_MICROSECONDS, 3, 1000);
+    enable_delay_microseconds = new IntSetting(EXTENDED, WG, NULL, "Stepper/Enable/Delay", DEFAULT_STEP_ENABLE_DELAY, 0, 1000);  // microseconds
 
     stallguard_debug_mask = new AxisMaskSetting(EXTENDED, WG, NULL, "Report/StallGuard", 0, postMotorSetting);
 

Grbl_Esp32/src/SettingsDefinitions.h

@@ -18,6 +18,7 @@ extern StringSetting* build_info;
 
 extern IntSetting* pulse_microseconds;
 extern IntSetting* stepper_idle_lock_time;
+extern IntSetting* enable_delay_microseconds;
 
 extern AxisMaskSetting* step_invert_mask;
 extern AxisMaskSetting* dir_invert_mask;