Make TPA configurable to affect P/D or D only

Adds a new `tpa_mode` parameter that accepts `PD` (default) and `D`. Allows the user to configer to affect P/D as it always has, or switch to D-only mode.

Note: the `tpa_mode` parameter was added to the PID Profile instead of rate profiles with the other TPA parameters. This can be discussed, but I didn't think it made sense to have this be part of rate profiles as it affects PID tuning (the same argument could be made for the other TPA parameters).

Code is wrapped in `USE_TPA_MODE` so it can be disabled if needed.

src/main/flight/pid.c

@@ -175,6 +175,7 @@ void resetPidProfile(pidProfile_t *pidProfile)
         .launchControlAngleLimit = 0,
         .launchControlGain = 40,
         .launchControlAllowTriggerReset = true,
+        .tpaMode = TPA_MODE_PD,
     );
 #ifdef USE_DYN_LPF
     pidProfile->dterm_lowpass_hz = 120;
@@ -434,6 +435,10 @@ static FAST_RAM_ZERO_INIT uint8_t launchControlAngleLimit;
 static FAST_RAM_ZERO_INIT float launchControlKi;
 #endif
 
+#ifdef USE_TPA_MODE
+static FAST_RAM_ZERO_INIT uint8_t tpaMode;
+#endif
+
 void pidResetIterm(void)
 {
     for (int axis = 0; axis < 3; axis++) {
@@ -576,6 +581,10 @@ void pidInitConfig(const pidProfile_t *pidProfile)
     }
     launchControlKi = ITERM_SCALE * pidProfile->launchControlGain;
 #endif
+
+#ifdef USE_TPA_MODE
+    tpaMode = pidProfile->tpaMode;
+#endif
 }
 
 void pidInit(const pidProfile_t *pidProfile)
@@ -1048,6 +1057,12 @@ void FAST_CODE pidController(const pidProfile_t *pidProfile, const rollAndPitchT
 
     const float tpaFactor = getThrottlePIDAttenuation();
 
+#ifdef USE_TPA_MODE
+    const float tpaFactorKp = (tpaMode == TPA_MODE_PD) ? tpaFactor : 1.0f;
+#else
+    const float tpaFactorKp = tpaFactor;
+#endif
+
 #ifdef USE_YAW_SPIN_RECOVERY
     const bool yawSpinActive = gyroYawSpinDetected();
 #endif
@@ -1145,7 +1160,7 @@ void FAST_CODE pidController(const pidProfile_t *pidProfile, const rollAndPitchT
         // b = 1 and only c (feedforward weight) can be tuned (amount derivative on measurement or error).
 
         // -----calculate P component
-        pidData[axis].P = pidCoefficient[axis].Kp * errorRate * tpaFactor;
+        pidData[axis].P = pidCoefficient[axis].Kp * errorRate * tpaFactorKp;
         if (axis == FD_YAW) {
             pidData[axis].P = ptermYawLowpassApplyFn((filter_t *) &ptermYawLowpass, pidData[axis].P);
         }

src/main/flight/pid.h

@@ -97,6 +97,11 @@ typedef enum {
     ITERM_RELAX_SETPOINT
 } itermRelaxType_e;
 
+typedef enum {
+    TPA_MODE_PD,
+    TPA_MODE_D
+} tpaMode_e;
+
 typedef struct pidProfile_s {
     uint16_t yaw_lowpass_hz;                // Additional yaw filter when yaw axis too noisy
     uint16_t dterm_lowpass_hz;              // Delta Filter in hz
@@ -156,6 +161,7 @@ typedef struct pidProfile_s {
     uint8_t launchControlAngleLimit;        // Optional launch control angle limit (requires ACC)
     uint8_t launchControlGain;              // Iterm gain used while launch control is active
     uint8_t launchControlAllowTriggerReset; // Controls trigger behavior and whether the trigger can be reset
+    uint8_t tpaMode;                        // Controls which PID terms TPA effects
 } pidProfile_t;
 
 PG_DECLARE_ARRAY(pidProfile_t, MAX_PROFILE_COUNT, pidProfiles);

src/main/interface/settings.c

@@ -407,6 +407,12 @@ static const char * const lookupTableLaunchControlMode[] = {
 };
 #endif
 
+#ifdef USE_TPA_MODE
+static const char * const lookupTableTpaMode[] = {
+    "PD", "D"
+};
+#endif
+
 #define LOOKUP_TABLE_ENTRY(name) { name, ARRAYLEN(name) }
 
 const lookupTableEntry_t lookupTables[] = {
@@ -510,6 +516,9 @@ const lookupTableEntry_t lookupTables[] = {
 #ifdef USE_LAUNCH_CONTROL
     LOOKUP_TABLE_ENTRY(lookupTableLaunchControlMode),
 #endif
+#ifdef USE_TPA_MODE
+    LOOKUP_TABLE_ENTRY(lookupTableTpaMode),
+#endif
 };
 
 #undef LOOKUP_TABLE_ENTRY
@@ -929,6 +938,10 @@ const clivalue_t valueTable[] = {
     { "launch_control_gain",        VAR_UINT8 | PROFILE_VALUE,  .config.minmax = { 0, 200 }, PG_PID_PROFILE, offsetof(pidProfile_t, launchControlGain) },
 #endif
 
+#ifdef USE_TPA_MODE
+    { "tpa_mode",                   VAR_UINT8  | PROFILE_VALUE | MODE_LOOKUP, .config.lookup = { TABLE_TPA_MODE }, PG_PID_PROFILE, offsetof(pidProfile_t, tpaMode) },
+#endif
+
 // PG_TELEMETRY_CONFIG
 #ifdef USE_TELEMETRY
     { "tlm_inverted",               VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP, .config.lookup = { TABLE_OFF_ON }, PG_TELEMETRY_CONFIG, offsetof(telemetryConfig_t, telemetry_inverted) },

src/main/interface/settings.h

@@ -125,6 +125,9 @@ typedef enum {
 #endif
 #ifdef USE_LAUNCH_CONTROL
     TABLE_LAUNCH_CONTROL_MODE,
+#endif
+#ifdef USE_TPA_MODE
+    TABLE_TPA_MODE,
 #endif
     LOOKUP_TABLE_COUNT
 } lookupTableIndex_e;

src/main/target/common_pre.h

@@ -177,6 +177,7 @@
 #define USE_RTC_TIME
 #define USE_RX_MSP
 #define USE_SERIALRX_FPORT      // FrSky FPort
+#define USE_TPA_MODE
 #define USE_TELEMETRY_CRSF
 #define USE_TELEMETRY_SRXL
 #define USE_VIRTUAL_CURRENT_METER