Added generic artifical FF_SPRING effect using FF_CONSTANT in Python.

Scripts/Generic/artificial_spring_effect.py

@@ -0,0 +1,165 @@
+import os
+from time import sleep, time
+
+from evdev import InputDevice, ecodes, ff, list_devices
+
+"""
+==============================================================================
+Project:     Universal Constant-Force Spring Emulator
+Author:      Stan Swanborn
+Description: This script provides a software-based "Spring" effect for Force
+             Feedback (FFB) steering wheels on Linux. It is specifically
+             designed for Direct Drive (DD) wheelbases that may lack native
+             FF_SPRING support.
+
+Functionality:
+    1. Auto-detects the first available Force Feedback device.
+        1.1 Manual override for input event available.
+    2. Monitors the wheel's ABS_X axis position.
+    3. Calculates a reactive centering force using a configurable Root-Curve.
+    4. Updates the FF_CONSTANT effect at high frequency (up to 1000Hz).
+
+Usage:
+    Run WITHOUT sudo/root privileges, it is able to see any input device
+        evtest would be able to see. If it cannot find your device, make a
+        custom udev rule allowing access on the user level.
+
+    Adjust MAX_FORCE_PERCENT and POWER_FACTOR to tune the feel.
+==============================================================================
+"""
+
+# ================== CONFIG ==================
+DEVICE_PATH = None  # When set to None, we will find the first Force Feedback device. Override here if necessary with correct /dev/input/eventXX
+MIN_UPDATE_INTERVAL = 0.001  # 1ms (1000Hz) - Max precision for DD
+# FORCE SETTINGS
+MAX_FORCE_PERCENT = 10.0
+# POWER_FACTOR (Sensitivity):
+# 1.0 = Linear
+# 0.5 = Square Root (Very sensitive at center, zero at zero)
+# 0.7 = Good middle ground for "quick pick up"
+POWER_FACTOR = 0.65
+# ===========================================
+
+
+def find_ff_device():
+    """Finds the first device that supports Force Feedback."""
+    devices = [InputDevice(path) for path in list_devices()]
+    for device in devices:
+        # Check if EV_FF (Force Feedback) is in the device's capabilities
+        if ecodes.EV_FF in device.capabilities():
+            return device
+    return None
+
+
+def percent_to_level(percent: float) -> int:
+    """Convert 0-100% to unsigned magnitude (0-32767)"""
+    return int((max(0, min(100, percent)) / 100.0) * 32767)
+
+
+# --- DEVICE INITIALIZATION ---
+ff_device = None
+
+if DEVICE_PATH:
+    try:
+        ff_device = InputDevice(DEVICE_PATH)
+    except Exception as e:
+        print(f"❌ Error: Could not open specified device {DEVICE_PATH}: {e}")
+else:
+    print("🔍 Searching for Force Feedback devices...")
+    ff_device = find_ff_device()
+
+if not ff_device:
+    print("❌ Error: No Force Feedback device found!")
+    exit(1)
+
+print(f"✅ Using Device: {ff_device.name} ({ff_device.path})")
+
+# --- CALIBRATION ---
+# Use .absinfo() to get the actual min/max/fuzz/flat data for the axis
+abs_info = ff_device.absinfo(ecodes.ABS_X)
+if abs_info:
+    CENTER = (abs_info.max + abs_info.min) / 2
+    print(f"✅ Calibrated Center: {CENTER} (Range: {abs_info.min} - {abs_info.max})")
+else:
+    CENTER = 32768
+    print("⚠️ Could not detect axis range, using fallback.")
+
+
+os.set_blocking(ff_device.fd, False)
+
+# 1. PRE-CREATE THE EFFECT OBJECT
+constant_eff = ff.Constant(level=0, envelope=ff.Envelope(0, 0, 0, 0))
+effect = ff.Effect(
+    ecodes.FF_CONSTANT,
+    -1,
+    0,
+    ff.Trigger(0, 0),
+    ff.Replay(0, 0),
+    ff.EffectType(ff_constant_effect=constant_eff),
+)
+
+# 2. INITIAL UPLOAD AND START
+eff_id = ff_device.upload_effect(effect)
+effect.id = eff_id
+ff_device.write(ecodes.EV_FF, eff_id, 1)
+
+print(f"✅ Root-Curve Spring Active on {ff_device.name}")
+print(f"🚀 Sensitivity: {POWER_FACTOR} (Lower is more sensitive at center)")
+
+last_update = 0
+last_level = 0
+
+try:
+    while True:
+        try:
+            for event in ff_device.read():
+                if event.type == ecodes.EV_ABS and event.code == ecodes.ABS_X:
+                    now = time()
+                    if now - last_update < MIN_UPDATE_INTERVAL:
+                        continue
+
+                    # Calculate deviation
+                    deviation = event.value - CENTER
+
+                    if deviation == 0:
+                        level = 0
+                    else:
+                        normalized_dev = abs(deviation) / CENTER
+
+                        # ROOT CALCULATION:
+                        # Power < 1.0 makes the curve steep at the start but keeps 0 at 0.
+                        target_pct = MAX_FORCE_PERCENT * (normalized_dev**POWER_FACTOR)
+                        magnitude = percent_to_level(target_pct)
+
+                        # DIRECTIONAL LOGIC (PERSISTED):
+                        # Deviation > 0 (Left) -> Negative Force (Pull Right)
+                        # Deviation < 0 (Right) -> Positive Force (Pull Left)
+                        if deviation > 0:
+                            level = magnitude
+                        else:
+                            level = -magnitude
+
+                    # 3. UPDATE IN-PLACE
+                    if level != last_level:
+                        effect.u.ff_constant_effect.level = level
+                        ff_device.upload_effect(effect)
+                        last_level = level
+                        last_update = now
+
+        except BlockingIOError:
+            pass
+
+        # Reduced sleep for 1000Hz potential
+        sleep(0.0001)
+
+except KeyboardInterrupt:
+    print("\nStopping...")
+finally:
+    if "ff_device" in locals():
+        try:
+            ff_device.write(ecodes.EV_FF, effect.id, 0)
+            ff_device.erase_effect(effect.id)
+            ff_device.close()
+            print("Cleaned up.")
+        except:
+            pass