Make step pulse timing per-driver instance members; add setMinStepPulse (fixes #136)

AGENTS.md

@@ -170,8 +170,14 @@ All CI must pass before merging PRs.
 - Must respect driver parameters such as microstep configuration, signal timing, etc. as documented in the driver chip datasheet
 
 ### Timing Constraints
-- `step_high_min` / `step_low_min`: Minimum pulse durations (μs) - driver-specific
-- `wakeup_time`: Time after enabling before movement (μs)
+- `step_high_min` / `step_low_min`: Minimum pulse durations (μs) - driver-specific.
+  These are instance members; each driver defines a protected inline `initTiming()`
+  method in its header with the datasheet values and calls it from every constructor.
+  The base default is 1μs. Users can override at runtime with
+  `setMinStepPulse(high_us, low_us)` (needed on very fast MCUs like the Arduino Opta
+  whose GPIO outpaces the driver).
+- `wakeup_time`: Time after enabling before movement (μs), instance member set by the
+  driver's `initTiming()` (base default 0, floored to 2μs in `enable()`).
 - High RPM + high microstepping = limited by MCU speed
 
 ### Movement Modes
@@ -222,7 +228,9 @@ Before modifying timing-critical code paths:
 3. Inherit from appropriate base class (typically `A4988` or `DRV8825`)
 4. Override `getMaxMicrostep()` if different from parent
 5. Override `setMicrostep()` if pin configuration differs
-6. Update timing constants if needed (`step_high_min`, `wakeup_time`)
+6. Update timing values if needed by defining a protected inline `initTiming()` method
+   in the driver's header that assigns `step_high_min`, `step_low_min`, and
+   `wakeup_time` (instance members), and calling it from every constructor
 7. Add to `keywords.txt` for Arduino IDE highlighting
 8. Create an example sketch in `examples/`
 

keywords.txt

@@ -16,6 +16,9 @@ move	KEYWORD2
 rotate	KEYWORD2
 setRPM	KEYWORD2
 getRPM	KEYWORD2
+setMinStepPulse	KEYWORD2
+getMinStepPulseHigh	KEYWORD2
+getMinStepPulseLow	KEYWORD2
 setCurrent	KEYWORD2
 enable	KEYWORD2
 disable	KEYWORD2

src/A4988.cpp

@@ -21,11 +21,11 @@ const uint8_t A4988::MS_TABLE[] = {0b000, 0b001, 0b010, 0b011, 0b111};
  */
 A4988::A4988(short steps, short dir_pin, short step_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin)
-{}
+{ initTiming(); }
 
 A4988::A4988(short steps, short dir_pin, short step_pin, short enable_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin)
-{}
+{ initTiming(); }
 
 /*
  * Fully wired.
@@ -34,12 +34,12 @@ A4988::A4988(short steps, short dir_pin, short step_pin, short enable_pin)
 A4988::A4988(short steps, short dir_pin, short step_pin, short ms1_pin, short ms2_pin, short ms3_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin),
     ms1_pin(ms1_pin), ms2_pin(ms2_pin), ms3_pin(ms3_pin)
-{}
+{ initTiming(); }
 
 A4988::A4988(short steps, short dir_pin, short step_pin, short enable_pin, short ms1_pin, short ms2_pin, short ms3_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin),
 ms1_pin(ms1_pin), ms2_pin(ms2_pin), ms3_pin(ms3_pin)
-{}
+{ initTiming(); }
 
 void A4988::begin(float rpm, short microsteps){
     BasicStepperDriver::begin(rpm, microsteps);

src/A4988.h

@@ -18,12 +18,15 @@ class A4988 : public BasicStepperDriver {
     short ms1_pin = PIN_UNCONNECTED;
     short ms2_pin = PIN_UNCONNECTED;
     short ms3_pin = PIN_UNCONNECTED;
-    // tA STEP minimum, HIGH pulse width (1us)
-    static const int step_high_min = 1;
-    // tB STEP minimum, LOW pulse width (1us)
-    static const int step_low_min = 1;
-    // wakeup time, nSLEEP inactive to STEP (1000us)
-    static const int wakeup_time = 1000;
+    // Set timing requirements from A4988 datasheet
+    void initTiming(){
+        // tA STEP HIGH pulse duration, min value (1us)
+        step_high_min = 1;
+        // tB STEP LOW pulse duration, min value (1us)
+        step_low_min = 1;
+        // tWAKE wakeup time, nSLEEP inactive to STEP (1000us)
+        wakeup_time = 1000;
+    }
     // also 200ns between ENBL/DIR/MSx changes and STEP HIGH
 
     // Get the microstep table

src/BasicStepperDriver.cpp

@@ -342,7 +342,9 @@ long BasicStepperDriver::nextAction(void){
         // account for calcStepPulse() execution time; sets ceiling for max rpm on slower MCUs
         last_action_end = micros();
         m = last_action_end - m;
-        next_action_interval = (pulse > m) ? pulse - m : 1;
+        // floor the STEP LOW interval at step_low_min (datasheet tWL) instead of 1us
+        unsigned low_min = (unsigned)step_low_min;
+        next_action_interval = (pulse > m + low_min) ? pulse - m : low_min;
     } else {
         // end of move
         last_action_end = 0;
@@ -380,7 +382,9 @@ void BasicStepperDriver::enable(void){
     if IS_CONNECTED(enable_pin){
         digitalWrite(enable_pin, enable_active_state);
     };
-    delayMicros(2);
+    // wait the driver's wakeup time (datasheet tWAKE) before stepping,
+    // but at least 2us as the base default wakeup_time is 0
+    delayMicros(stepperMax((short)2, wakeup_time));
 }
 
 void BasicStepperDriver::disable(void){

src/BasicStepperDriver.h

@@ -74,11 +74,13 @@ class BasicStepperDriver {
     // current microstep level (1,2,4,8,...), must be < getMaxMicrostep()
     short microsteps = 1;
     // tWH(STEP) pulse duration, STEP high, min value (us)
-    static const int step_high_min = 1;
+    // Instance members (not static const) so derived drivers can set datasheet
+    // values in their constructors and users can override via setMinStepPulse().
+    short step_high_min = 1;
     // tWL(STEP) pulse duration, STEP low, min value (us)
-    static const int step_low_min = 1;
+    short step_low_min = 1;
     // tWAKE wakeup time, nSLEEP inactive to STEP (us)
-    static const int wakeup_time = 0;
+    short wakeup_time = 0;
 
     float rpm = 0;
 
@@ -137,6 +139,22 @@ class BasicStepperDriver {
     float getCurrentRPM(void){
         return (60.0*1000000L / step_pulse / microsteps / motor_steps);
     }
+    /*
+     * Set minimum STEP pulse HIGH and LOW durations (microseconds).
+     * Useful on fast MCUs (e.g. Arduino Opta) whose GPIO toggles faster than
+     * the driver can register the default 1us pulses. See issue #136.
+     */
+    void setMinStepPulse(short high_us, short low_us){
+        step_high_min = (high_us > 0) ? high_us : 0;
+        // LOW interval must stay >= 1: nextAction() returning 0 means move complete
+        step_low_min = (low_us > 1) ? low_us : 1;
+    }
+    short getMinStepPulseHigh(void){
+        return step_high_min;
+    }
+    short getMinStepPulseLow(void){
+        return step_low_min;
+    }
     /*
      * Set speed profile - CONSTANT_SPEED, LINEAR_SPEED (accelerated)
      * accel and decel are given in [full steps/s^2]

src/DRV8825.cpp

@@ -17,22 +17,22 @@ const uint8_t DRV8825::MS_TABLE[] = {0b000, 0b001, 0b010, 0b011, 0b100, 0b111};
 
 DRV8825::DRV8825(short steps, short dir_pin, short step_pin)
 :A4988(steps, dir_pin, step_pin)
-{}
+{ initTiming(); }
 
 DRV8825::DRV8825(short steps, short dir_pin, short step_pin, short enable_pin)
 :A4988(steps, dir_pin, step_pin, enable_pin)
-{}
+{ initTiming(); }
 
 /*
  * A4988-DRV8825 Compatibility map: MS1-MODE0, MS2-MODE1, MS3-MODE2
  */
 DRV8825::DRV8825(short steps, short dir_pin, short step_pin, short mode0_pin, short mode1_pin, short mode2_pin)
 :A4988(steps, dir_pin, step_pin, mode0_pin, mode1_pin, mode2_pin)
-{}
+{ initTiming(); }
 
 DRV8825::DRV8825(short steps, short dir_pin, short step_pin, short enable_pin, short mode0_pin, short mode1_pin, short mode2_pin)
 :A4988(steps, dir_pin, step_pin, enable_pin, mode0_pin, mode1_pin, mode2_pin)
-{}
+{ initTiming(); }
 
 const uint8_t* DRV8825::getMicrostepTable()
 {

src/DRV8825.h

@@ -15,12 +15,15 @@
 class DRV8825 : public A4988 {
 protected:
     static const uint8_t MS_TABLE[];
-    // tWH(STEP) pulse duration, STEP high, min value (1.9us)
-    static const int step_high_min = 2;
-    // tWL(STEP) pulse duration, STEP low, min value (1.9us)
-    static const int step_low_min = 2;
-    // tWAKE wakeup time, nSLEEP inactive to STEP (1000us)
-    static const int wakeup_time = 1700;
+    // Set timing requirements from DRV8825 datasheet
+    void initTiming(){
+        // tWH(STEP) pulse duration, STEP high, min value (1.9us)
+        step_high_min = 2;
+        // tWL(STEP) pulse duration, STEP low, min value (1.9us)
+        step_low_min = 2;
+        // tWAKE wakeup time, nSLEEP inactive to STEP (1700us)
+        wakeup_time = 1700;
+    }
     // also 650ns between ENBL/DIR/MODEx changes and STEP HIGH
 
     // Get the microstep table

src/DRV8834.cpp

@@ -15,22 +15,22 @@
  */
 DRV8834::DRV8834(short steps, short dir_pin, short step_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin)
-{}
+{ initTiming(); }
 
 DRV8834::DRV8834(short steps, short dir_pin, short step_pin, short enable_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin)
-{}
+{ initTiming(); }
 
 /*
  * Fully wired. All the necessary control pins for DRV8834 are connected.
  */
 DRV8834::DRV8834(short steps, short dir_pin, short step_pin, short m0_pin, short m1_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin), m0_pin(m0_pin), m1_pin(m1_pin)
-{}
+{ initTiming(); }
 
 DRV8834::DRV8834(short steps, short dir_pin, short step_pin, short enable_pin, short m0_pin, short m1_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin), m0_pin(m0_pin), m1_pin(m1_pin)
-{}
+{ initTiming(); }
 
 /*
  * Set microstepping mode (1:divisor)

src/DRV8834.h

@@ -16,12 +16,15 @@ class DRV8834 : public BasicStepperDriver {
 protected:
     short m0_pin = PIN_UNCONNECTED;
     short m1_pin = PIN_UNCONNECTED;
-    // tWH(STEP) pulse duration, STEP high, min value (1.9us)
-    static const int step_high_min = 2;
-    // tWL(STEP) pulse duration, STEP low, min value (1.9us)
-    static const int step_low_min = 2;
-    // tWAKE wakeup time, nSLEEP inactive to STEP (1000us)
-    static const int wakeup_time = 1000;
+    // Set timing requirements from DRV8834 datasheet
+    void initTiming(){
+        // tWH(STEP) pulse duration, STEP high, min value (1.9us)
+        step_high_min = 2;
+        // tWL(STEP) pulse duration, STEP low, min value (1.9us)
+        step_low_min = 2;
+        // tWAKE wakeup time, nSLEEP inactive to STEP (1000us)
+        wakeup_time = 1000;
+    }
     // also 200ns between ENBL/DIR/Mx changes and STEP HIGH
 
     // Get max microsteps supported by the device

src/DRV8880.cpp

@@ -14,30 +14,30 @@
  */
 DRV8880::DRV8880(short steps, short dir_pin, short step_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin)
-{}
+{ initTiming(); }
 
 DRV8880::DRV8880(short steps, short dir_pin, short step_pin, short enable_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin)
-{}
+{ initTiming(); }
 
 /*
  * Fully wired. All the necessary control pins for DRV8880 are connected.
  */
 DRV8880::DRV8880(short steps, short dir_pin, short step_pin, short m0, short m1)
 :BasicStepperDriver(steps, dir_pin, step_pin), m0(m0), m1(m1)
-{}
+{ initTiming(); }
 
 DRV8880::DRV8880(short steps, short dir_pin, short step_pin, short enable_pin, short m0, short m1)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin), m0(m0), m1(m1)
-{}
+{ initTiming(); }
 
 DRV8880::DRV8880(short steps, short dir_pin, short step_pin, short m0, short m1, short trq0, short trq1)
 :BasicStepperDriver(steps, dir_pin, step_pin), m0(m0), m1(m1), trq0(trq0), trq1(trq1)
-{}
+{ initTiming(); }
 
 DRV8880::DRV8880(short steps, short dir_pin, short step_pin, short enable_pin, short m0, short m1, short trq0, short trq1)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin), m0(m0), m1(m1), trq0(trq0), trq1(trq1)
-{}
+{ initTiming(); }
 
 void DRV8880::begin(float rpm, short microsteps){
     BasicStepperDriver::begin(rpm, microsteps);

src/DRV8880.h

@@ -17,12 +17,19 @@ class DRV8880 : public BasicStepperDriver {
     short m1 = PIN_UNCONNECTED;
     short trq0 = PIN_UNCONNECTED;
     short trq1 = PIN_UNCONNECTED;
-    // tWH(STEP) pulse duration, STEP high, min value
-    static const int step_high_min = 0;   // 0.47us
-    // tWL(STEP) pulse duration, STEP low, min value
-    static const int step_low_min = 0;    // 0.47us
-    // tWAKE wakeup time, nSLEEP inactive to STEP
-    static const int wakeup_time = 1500;
+    // Set timing requirements from DRV8880 datasheet
+    void initTiming(){
+        // tWH(STEP) pulse duration, STEP high, min value (0.47us -> 1;
+        // rounded up because a 0 delay could produce sub-datasheet pulses
+        // on fast ARM boards)
+        step_high_min = 1;
+        // tWL(STEP) pulse duration, STEP low, min value (0.47us -> 1;
+        // rounded up because a 0 delay could produce sub-datasheet pulses
+        // on fast ARM boards)
+        step_low_min = 1;
+        // tWAKE wakeup time, nSLEEP inactive to STEP (1500us)
+        wakeup_time = 1500;
+    }
     // also 200ns between ENBL/DIR/Mx changes and STEP HIGH
 
     // Get max microsteps supported by the device

src/TMC2100.cpp

@@ -12,11 +12,11 @@
  */
 TMC2100::TMC2100(short steps, short dir_pin, short step_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin)
-{}
+{ initTiming(); }
 
 TMC2100::TMC2100(short steps, short dir_pin, short step_pin, short enable_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin)
-{}
+{ initTiming(); }
 
 /*
  * Fully wired.
@@ -25,12 +25,12 @@ TMC2100::TMC2100(short steps, short dir_pin, short step_pin, short enable_pin)
 TMC2100::TMC2100(short steps, short dir_pin, short step_pin, short cf1_pin, short cf2_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin),
     cf1_pin(cf1_pin), cf2_pin(cf2_pin)
-{}
+{ initTiming(); }
 
 TMC2100::TMC2100(short steps, short dir_pin, short step_pin, short enable_pin, short cf1_pin, short cf2_pin)
 :BasicStepperDriver(steps, dir_pin, step_pin, enable_pin),
 cf1_pin(cf1_pin), cf2_pin(cf2_pin)
-{}
+{ initTiming(); }
 
 void TMC2100::begin(float rpm, short microsteps){
     BasicStepperDriver::begin(rpm, microsteps);

src/TMC2100.h

@@ -13,12 +13,15 @@ class TMC2100 : public BasicStepperDriver {
 protected:
     short cf1_pin = PIN_UNCONNECTED;
     short cf2_pin = PIN_UNCONNECTED;
-    // tA STEP minimum, HIGH pulse width (1us)
-    static const int step_high_min = 1;
-    // tB STEP minimum, LOW pulse width (1us)
-    static const int step_low_min = 1;
-    // wakeup time, nSLEEP inactive to STEP (1000us)
-    static const int wakeup_time = 1000;
+    // Set timing requirements from TMC2100 datasheet
+    void initTiming(){
+        // tA STEP HIGH pulse duration, min value (1us)
+        step_high_min = 1;
+        // tB STEP LOW pulse duration, min value (1us)
+        step_low_min = 1;
+        // tWAKE wakeup time, nSLEEP inactive to STEP (1000us)
+        wakeup_time = 1000;
+    }
 
     // Get max microsteps supported by the device
     short getMaxMicrostep() override;