RC Smoothing: added parameter to allow user to adjust the smoothness of the auto cutoff calc

Adds `rc_smoothing_auto_smoothness` parameter that allows the user to tune the filter auto cutoff calculation. Increasing the value makes the resulting rcCommand traces smoother.

Allows the user to retain the "auto" calculation which is important for protocols that can change rate (like CRSF), but still tune the resulting "smoothness" to their preference.

src/main/blackbox/blackbox.c

@@ -1333,6 +1333,7 @@ static bool blackboxWriteSysinfo(void)
         BLACKBOX_PRINT_HEADER_LINE("rc_smoothing_debug_axis", "%d",         rxConfig()->rc_smoothing_debug_axis);
         BLACKBOX_PRINT_HEADER_LINE("rc_smoothing_cutoffs", "%d, %d",        rxConfig()->rc_smoothing_input_cutoff,
                                                                             rxConfig()->rc_smoothing_derivative_cutoff);
+        BLACKBOX_PRINT_HEADER_LINE("rc_smoothing_auto_factor", "%d",        rxConfig()->rc_smoothing_auto_factor);
         BLACKBOX_PRINT_HEADER_LINE("rc_smoothing_filter_type", "%d, %d",    rxConfig()->rc_smoothing_input_type,
                                                                             rxConfig()->rc_smoothing_derivative_type);
         BLACKBOX_PRINT_HEADER_LINE("rc_smoothing_active_cutoffs", "%d, %d", rcSmoothingGetValue(RC_SMOOTHING_VALUE_INPUT_ACTIVE),

src/main/fc/rc.c

@@ -288,8 +288,9 @@ FAST_CODE uint8_t processRcInterpolation(void)
 FAST_CODE_NOINLINE int calcRcSmoothingCutoff(int avgRxFrameTimeUs, bool pt1)
 {
     if (avgRxFrameTimeUs > 0) {
+        const float cutoffFactor = (100 - rxConfig()->rc_smoothing_auto_factor) / 100.0f;
         float cutoff = (1 / (avgRxFrameTimeUs * 1e-6f)) / 2;  // calculate the nyquist frequency
-        cutoff = cutoff * 0.90f;  // Use 90% of the calculated nyquist frequency
+        cutoff = cutoff * cutoffFactor;
 
         if (pt1) {
             cutoff = sq(cutoff) / RC_SMOOTHING_IDENTITY_FREQUENCY; // convert to a cutoff for pt1 that has similar characteristics

src/main/interface/settings.c

@@ -631,6 +631,7 @@ const clivalue_t valueTable[] = {
     { "rc_smoothing_debug_axis",    VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP, .config.lookup = { TABLE_RC_SMOOTHING_DEBUG }, PG_RX_CONFIG, offsetof(rxConfig_t, rc_smoothing_debug_axis) },
     { "rc_smoothing_input_type",    VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP, .config.lookup = { TABLE_RC_SMOOTHING_INPUT_TYPE }, PG_RX_CONFIG, offsetof(rxConfig_t, rc_smoothing_input_type) },
     { "rc_smoothing_derivative_type",VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP, .config.lookup = { TABLE_RC_SMOOTHING_DERIVATIVE_TYPE }, PG_RX_CONFIG, offsetof(rxConfig_t, rc_smoothing_derivative_type) },
+    { "rc_smoothing_auto_smoothness",VAR_UINT8  | MASTER_VALUE, .config.minmax = { 0, 50 }, PG_RX_CONFIG, offsetof(rxConfig_t, rc_smoothing_auto_factor) },
 #endif // USE_RC_SMOOTHING_FILTER
 
     { "fpv_mix_degrees",            VAR_UINT8  | MASTER_VALUE, .config.minmax = { 0, 90 }, PG_RX_CONFIG, offsetof(rxConfig_t, fpvCamAngleDegrees) },

src/main/pg/rx.c

@@ -67,6 +67,7 @@ void pgResetFn_rxConfig(rxConfig_t *rxConfig)
         .rc_smoothing_debug_axis = ROLL,     // default to debug logging for the roll axis
         .rc_smoothing_input_type = RC_SMOOTHING_INPUT_BIQUAD,
         .rc_smoothing_derivative_type = RC_SMOOTHING_DERIVATIVE_BIQUAD,
+        .rc_smoothing_auto_factor = 10,
     );
 
 #ifdef RX_CHANNELS_TAER

src/main/pg/rx.h

@@ -56,6 +56,7 @@ typedef struct rxConfig_s {
     uint8_t rc_smoothing_debug_axis;        // Axis to log as debug values when debug_mode = RC_SMOOTHING
     uint8_t rc_smoothing_input_type;        // Input filter type (0 = PT1, 1 = BIQUAD)
     uint8_t rc_smoothing_derivative_type;   // Derivative filter type (0 = OFF, 1 = PT1, 2 = BIQUAD)
+    uint8_t rc_smoothing_auto_factor;       // Used to adjust the "smoothness" determined by the auto cutoff calculations
 } rxConfig_t;
 
 PG_DECLARE(rxConfig_t, rxConfig);