Replace absolute stall threshold with delta-based detection

- Use exponential moving average (EMA) to track normal running current
- Detect stall when current spikes above average by STALL_DELTA_THRESHOLD (2.0A)
- Add stabilization period (500ms) after motor start to let EMA settle
- Stall confirmation requires spike to persist for STALL_CONFIRM_MS (100ms)
- EMA stops updating during stall to prevent threshold creep
- Removes dependency on absolute current threshold that varied with speed

include/config.h

@@ -34,9 +34,14 @@
 #define SENSE_RESISTOR 1000.0f        // 1kΩ sense resistor (ohms)
 #define ADC_MAX 4095.0f               // 12-bit ADC max value
 #define ADC_VREF 3.3f                 // ADC reference voltage
-#define CURRENT_CALIBRATION 0.33f    // Calibration factor (measured current / reported current)
-#define STALL_CURRENT_THRESHOLD 7.0f  // Current (amps) that indicates stall
-#define STALL_DETECT_TIME_MS 1000     // Time to confirm stall (ms) - accounts for startup inrush
+#define CURRENT_CALIBRATION 0.33f     // Calibration factor (measured current / reported current)
+
+// Stall Detection Configuration (delta-based)
+// Detects sudden current spikes above the rolling average
+#define STALL_DELTA_THRESHOLD 2.0f    // Current spike above average that indicates stall (amps)
+#define STALL_EMA_ALPHA 0.1f          // EMA smoothing factor (0.1 = slow, 0.5 = fast response)
+#define STALL_STABILIZE_MS 500        // Ignore stalls for this long after motor starts/changes
+#define STALL_CONFIRM_MS 100          // Current must exceed threshold for this long to confirm stall
 #define DISABLE_STALL_DETECT false    // Set to true to disable stall detection
 
 // Web Server

include/motor.h

@@ -45,6 +45,11 @@ private:
     int _adcOffsetRight = 0;
     int _adcOffsetLeft = 0;
     
+    // Delta-based stall detection (rolling average tracking)
+    float _currentEMA = 0;              // Exponential moving average of current
+    unsigned long _motorStartTime = 0;  // When motor started (for stabilization period)
+    bool _emaInitialized = false;       // EMA needs seeding on first reading
+    
     // Pingpong state
     bool _pingpongActive = false;
     int _pingpongBaseSpeed = 50;
@@ -61,6 +66,7 @@ private:
     float readCurrentSense(int pin);
     void calibrateCurrentOffset();
     void checkStall();
+    void resetStallDetection();
     void updatePingpong();
     int applyRandomness(int baseValue, int randomPercent);
 };