This fix is for avoiding yaw overshoot and bounce back for some

configurations
The hardcoded limit in the mixer and PID controllers 3-5 would be
removed
by default and will be configurable by CLI variables:

yaw_jump_prevention_limit, global setting (original fixed value was 100)
yaw_p_limit, per profile setting (fixed value was 300)

src/main/config/config.c

@@ -180,6 +180,8 @@ static void resetPidProfile(pidProfile_t *pidProfile)
     pidProfile->I8[PIDVEL] = 45;
     pidProfile->D8[PIDVEL] = 1;
 
+    pidProfile->yaw_p_limit = 0;
+
     pidProfile->P_f[ROLL] = 2.5f;     // new PID with preliminary defaults test carefully
     pidProfile->I_f[ROLL] = 0.6f;
     pidProfile->D_f[ROLL] = 0.06f;
@@ -317,6 +319,7 @@ void resetRcControlsConfig(rcControlsConfig_t *rcControlsConfig) {
 void resetMixerConfig(mixerConfig_t *mixerConfig) {
     mixerConfig->pid_at_min_throttle = 1;
     mixerConfig->yaw_direction = 1;
+    mixerConfig->yaw_jump_prevention_limit = 0;
 #ifdef USE_SERVOS
     mixerConfig->tri_unarmed_servo = 1;
     mixerConfig->servo_lowpass_freq = 400;

src/main/flight/mixer.c

@@ -564,9 +564,9 @@ void mixTable(void)
 {
     uint32_t i;
 
-    if (motorCount > 3) {
+    if (motorCount >= 4 &&  mixerConfig->yaw_jump_prevention_limit) {
         // prevent "yaw jump" during yaw correction
-        axisPID[YAW] = constrain(axisPID[YAW], -100 - ABS(rcCommand[YAW]), +100 + ABS(rcCommand[YAW]));
+        axisPID[YAW] = constrain(axisPID[YAW], -mixerConfig->yaw_jump_prevention_limit - ABS(rcCommand[YAW]), mixerConfig->yaw_jump_prevention_limit + ABS(rcCommand[YAW]));
     }
 
     // motors for non-servo mixes

src/main/flight/mixer.h

@@ -66,6 +66,7 @@ typedef struct mixer_t {
 typedef struct mixerConfig_s {
     uint8_t pid_at_min_throttle;            // when enabled pids are used at minimum throttle
     int8_t yaw_direction;
+    int8_t yaw_jump_prevention_limit;       // make limit configurable (original fixed value was 100)
 #ifdef USE_SERVOS
     uint8_t tri_unarmed_servo;              // send tail servo correction pulses even when unarmed
     int16_t servo_lowpass_freq;             // lowpass servo filter frequency selection; 1/1000ths of loop freq

src/main/flight/pid.c

@@ -297,7 +297,6 @@ static void pidMultiWii(pidProfile_t *pidProfile, controlRateConfig_t *controlRa
     }
 }
 
-#define GYRO_P_MAX 300
 #define GYRO_I_MAX 256
 
 static void pidMultiWii23(pidProfile_t *pidProfile, controlRateConfig_t *controlRateConfig, uint16_t max_angle_inclination,
@@ -394,9 +393,8 @@ static void pidMultiWii23(pidProfile_t *pidProfile, controlRateConfig_t *control
     PTerm = (int32_t)error * pidProfile->P8[FD_YAW] >> 6; // TODO: Bitwise shift on a signed integer is not recommended
 
     // Constrain YAW by D value if not servo driven in that case servolimits apply
-    if(motorCount > 3) {
+    if(motorCount >= 4 && pidProfile->yaw_p_limit) {
-        int16_t limit = GYRO_P_MAX - pidProfile->D8[FD_YAW];
+        PTerm = constrain(PTerm, -pidProfile->yaw_p_limit, pidProfile->yaw_p_limit);
-        PTerm = constrain(PTerm, -limit, +limit);
     }
 
     ITerm = constrain((int16_t)(errorGyroI[FD_YAW] >> 13), -GYRO_I_MAX, +GYRO_I_MAX);
@@ -505,9 +503,8 @@ static void pidMultiWiiHybrid(pidProfile_t *pidProfile, controlRateConfig_t *con
     PTerm = (int32_t)error * pidProfile->P8[FD_YAW] >> 6;
 
     // Constrain YAW by D value if not servo driven in that case servolimits apply
-    if(motorCount > 3) {
+    if(motorCount >= 4 && pidProfile->yaw_p_limit) {
-        int16_t limit = GYRO_P_MAX - pidProfile->D8[FD_YAW];
+        PTerm = constrain(PTerm, -pidProfile->yaw_p_limit, pidProfile->yaw_p_limit);
-        PTerm = constrain(PTerm, -limit, +limit);
     }
 
     ITerm = constrain((int16_t)(errorGyroI[FD_YAW] >> 13), -GYRO_I_MAX, +GYRO_I_MAX);
@@ -635,10 +632,8 @@ rollAndPitchTrims_t *angleTrim, rxConfig_t *rxConfig)
         ITerm = constrain(errorGyroI[FD_YAW] >> 13, -GYRO_I_MAX, +GYRO_I_MAX);
         PTerm = ((int32_t)error * (int32_t)pidProfile->P8[FD_YAW]) >> 6;
 
-        if (motorCount >= 4) { // Constrain FD_YAW by D value if not servo driven in that case servolimits apply
+        if(motorCount >= 4 && pidProfile->yaw_p_limit) {                       // Constrain FD_YAW by D value if not servo driven in that case servolimits apply
-            int32_t limit = 300;
+            PTerm = constrain(PTerm, -pidProfile->yaw_p_limit, pidProfile->yaw_p_limit);
-            if (pidProfile->D8[FD_YAW]) limit -= (int32_t)pidProfile->D8[FD_YAW];
-            PTerm = constrain(PTerm, -limit, limit);
         }
     }
     axisPID[FD_YAW] = PTerm + ITerm;

src/main/flight/pid.h

@@ -47,6 +47,7 @@ typedef struct pidProfile_s {
     float A_level;
     float H_level;
     uint8_t H_sensitivity;
+    uint16_t yaw_p_limit;                   // set P term limit (fixed value was 300)
 } pidProfile_t;
 
 #define DEGREES_TO_DECIDEGREES(angle) (angle * 10)

src/main/io/serial_cli.c

@@ -387,6 +387,7 @@ const clivalue_t valueTable[] = {
 
     { "pid_at_min_throttle",        VAR_UINT8  | MASTER_VALUE, &masterConfig.mixerConfig.pid_at_min_throttle, 0, 1 },
     { "yaw_direction",              VAR_INT8   | MASTER_VALUE, &masterConfig.mixerConfig.yaw_direction, -1, 1 },
+    { "yaw_jump_prevention_limit",  VAR_INT8   | MASTER_VALUE, &masterConfig.mixerConfig.yaw_jump_prevention_limit, 0, 250 },
 #ifdef USE_SERVOS
     { "tri_unarmed_servo",          VAR_INT8   | MASTER_VALUE, &masterConfig.mixerConfig.tri_unarmed_servo, 0, 1 },
     { "servo_lowpass_freq",         VAR_INT16  | MASTER_VALUE, &masterConfig.mixerConfig.servo_lowpass_freq, 10, 400},
@@ -470,6 +471,8 @@ const clivalue_t valueTable[] = {
     { "i_vel",                      VAR_UINT8  | PROFILE_VALUE, &masterConfig.profile[0].pidProfile.I8[PIDVEL], 0, 200 },
     { "d_vel",                      VAR_UINT8  | PROFILE_VALUE, &masterConfig.profile[0].pidProfile.D8[PIDVEL], 0, 200 },
 
+    { "yaw_p_limit",                VAR_UINT16 | PROFILE_VALUE, &masterConfig.profile[0].pidProfile.yaw_p_limit, 0, 500 },
+
 #ifdef BLACKBOX
     { "blackbox_rate_num",          VAR_UINT8  | MASTER_VALUE,  &masterConfig.blackbox_rate_num, 1, 32 },
     { "blackbox_rate_denom",        VAR_UINT8  | MASTER_VALUE,  &masterConfig.blackbox_rate_denom, 1, 32 },