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
 
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