make the accZ lpf used for althold configurable

set the variable accz_lpf_cutoff to the desired cutoff frequency
this can help to make althold smoother on copters with lots of
vibrations

Conflicts:

	src/cli.c
	src/config.c
	src/imu.c
	src/mw.h

src/main/config/config.c

@@ -85,7 +85,7 @@ static uint32_t flashWriteAddress = (0x08000000 + (uint32_t)((FLASH_PAGE_SIZE *
 master_t masterConfig;      // master config struct with data independent from profiles
 profile_t currentProfile;   // profile config struct
 
-static const uint8_t EEPROM_CONF_VERSION = 73;
+static const uint8_t EEPROM_CONF_VERSION = 74;
 
 static void resetAccelerometerTrims(flightDynamicsTrims_t *accelerometerTrims)
 {
@@ -305,6 +305,7 @@ static void resetConf(void)
 
     currentProfile.mag_declination = 0;
     currentProfile.acc_lpf_factor = 4;
+    currentProfile.accz_lpf_cutoff = 5.0f;
     currentProfile.accDeadband.xy = 40;
     currentProfile.accDeadband.z = 40;
 
@@ -425,6 +426,7 @@ void activateConfig(void)
     configureImu(&imuRuntimeConfig, &currentProfile.pidProfile, &currentProfile.barometerConfig, &currentProfile.accDeadband);
 
     calculateThrottleAngleScale(currentProfile.throttle_correction_angle);
+    calculateAccZLowPassFilterRCTimeConstant(currentProfile.accz_lpf_cutoff);
 
 #ifdef BARO
     useBarometerConfig(&currentProfile.barometerConfig);

src/main/config/config_profile.h

@@ -34,6 +34,7 @@ typedef struct profile_s {
 
     // sensor-related stuff
     uint8_t acc_lpf_factor;                 // Set the Low Pass Filter factor for ACC. Increasing this value would reduce ACC noise (visible in GUI), but would increase ACC lag time. Zero = no filter
+    float accz_lpf_cutoff;                  // cutoff frequency for the low pass filter used on the acc z-axis for althold in Hz
     accDeadband_t accDeadband;
 
     barometerConfig_t barometerConfig;
@@ -46,7 +47,7 @@ typedef struct profile_s {
     // Radio/ESC-related configuration
     uint8_t deadband;                       // introduce a deadband around the stick center for pitch and roll axis. Must be greater than zero.
     uint8_t yaw_deadband;                   // introduce a deadband around the stick center for yaw axis. Must be greater than zero.
-    uint8_t alt_hold_deadband;     // defines the neutral zone of throttle stick during altitude hold, default setting is +/-40
+    uint8_t alt_hold_deadband;              // defines the neutral zone of throttle stick during altitude hold, default setting is +/-40
     uint8_t alt_hold_fast_change;           // when disabled, turn off the althold when throttle stick is out of deadband defined with alt_hold_deadband; when enabled, altitude changes slowly proportional to stick movement
 
     uint16_t throttle_correction_angle;     // the angle when the throttle correction is maximal. in 0.1 degres, ex 225 = 22.5 ,30.0, 450 = 45.0 deg

src/main/flight/imu.c

@@ -61,6 +61,7 @@ int32_t errorAltitudeI = 0;
 int32_t vario = 0;                      // variometer in cm/s
 
 float throttleAngleScale;
+float fc_acc;
 
 int32_t BaroPID = 0;
 
@@ -103,6 +104,11 @@ void calculateThrottleAngleScale(uint16_t throttle_correction_angle)
     throttleAngleScale = (1800.0f / M_PI) * (900.0f / throttle_correction_angle);
 }
 
+void calculateAccZLowPassFilterRCTimeConstant(float accz_lpf_cutoff)
+{
+    fc_acc = 0.5f / (M_PI * accz_lpf_cutoff); // calculate RC time constant used in the accZ lpf
+}
+
 void computeIMU(rollAndPitchTrims_t *accelerometerTrims, uint8_t mixerConfiguration)
 {
     static int16_t gyroYawSmooth = 0;
@@ -207,9 +213,6 @@ int32_t applyDeadband(int32_t value, int32_t deadband)
     return value;
 }
 
-#define F_CUT_ACCZ 10.0f // 10Hz should still be fast enough
-static const float fc_acc = 0.5f / (M_PI * F_CUT_ACCZ);
-
 // rotate acc into Earth frame and calculate acceleration in it
 void acc_calc(uint32_t deltaT)
 {

src/main/flight/imu.h

@@ -35,3 +35,4 @@ void calculateEstimatedAltitude(uint32_t currentTime);
 void computeIMU(rollAndPitchTrims_t *accelerometerTrims, uint8_t mixerConfiguration);
 void calculateThrottleAngleScale(uint16_t throttle_correction_angle);
 int16_t calculateThrottleAngleCorrection(uint8_t throttle_correction_value);
+void calculateAccZLowPassFilterRCTimeConstant(float accz_lpf_cutoff);

src/main/io/serial_cli.c

@@ -296,6 +296,7 @@ const clivalue_t valueTable[] = {
     { "acc_lpf_factor", VAR_UINT8, &currentProfile.acc_lpf_factor, 0, 250 },
     { "accxy_deadband", VAR_UINT8, &currentProfile.accDeadband.xy, 0, 100 },
     { "accz_deadband", VAR_UINT8, &currentProfile.accDeadband.z, 0, 100 },
+    { "accz_lpf_cutoff", VAR_FLOAT, &currentProfile.accz_lpf_cutoff, 1, 20 },
     { "acc_unarmedcal", VAR_UINT8, &currentProfile.acc_unarmedcal, 0, 1 },
     { "acc_trim_pitch", VAR_INT16, &currentProfile.accelerometerTrims.values.pitch, -300, 300 },
     { "acc_trim_roll", VAR_INT16, &currentProfile.accelerometerTrims.values.roll, -300, 300 },