Use slightly flatter directory structure since some developers did not

like too many folders.
Extracted code from some files into separate files to fit with the new
layout.

src/flight_imu.c

@@ -0,0 +1,412 @@
+#include "board.h"
+#include "mw.h"
+
+#include "maths.h"
+
+int16_t gyroADC[3], accADC[3], accSmooth[3], magADC[3];
+int32_t accSum[3];
+uint32_t accTimeSum = 0;        // keep track for integration of acc
+int accSumCount = 0;
+int16_t accZ_25deg = 0;
+int32_t baroPressure = 0;
+int32_t baroTemperature = 0;
+uint32_t baroPressureSum = 0;
+int32_t BaroAlt = 0;
+int32_t sonarAlt;              // to think about the unit
+int32_t EstAlt;                // in cm
+int32_t BaroPID = 0;
+int32_t AltHold;
+int32_t errorAltitudeI = 0;
+int32_t vario = 0;                      // variometer in cm/s
+int16_t throttleAngleCorrection = 0;    // correction of throttle in lateral wind,
+float magneticDeclination = 0.0f;       // calculated at startup from config
+float accVelScale;
+
+// **************
+// gyro+acc IMU
+// **************
+int16_t gyroData[3] = { 0, 0, 0 };
+int16_t gyroZero[3] = { 0, 0, 0 };
+int16_t angle[2] = { 0, 0 };     // absolute angle inclination in multiple of 0.1 degree    180 deg = 1800
+float anglerad[2] = { 0.0f, 0.0f };    // absolute angle inclination in radians
+
+static void getEstimatedAttitude(void);
+
+void imuInit(void)
+{
+    accZ_25deg = acc_1G * cosf(RAD * 25.0f);
+    accVelScale = 9.80665f / acc_1G / 10000.0f;
+
+#ifdef MAG
+    // if mag sensor is enabled, use it
+    if (sensors(SENSOR_MAG))
+        Mag_init();
+#endif
+}
+
+void computeIMU(void)
+{
+    uint32_t axis;
+    static int16_t gyroYawSmooth = 0;
+
+    Gyro_getADC();
+    if (sensors(SENSOR_ACC)) {
+        ACC_getADC();
+        getEstimatedAttitude();
+    } else {
+        accADC[X] = 0;
+        accADC[Y] = 0;
+        accADC[Z] = 0;
+    }
+
+    if (mcfg.mixerConfiguration == MULTITYPE_TRI) {
+        gyroData[YAW] = (gyroYawSmooth * 2 + gyroADC[YAW]) / 3;
+        gyroYawSmooth = gyroData[YAW];
+        gyroData[ROLL] = gyroADC[ROLL];
+        gyroData[PITCH] = gyroADC[PITCH];
+    } else {
+        for (axis = 0; axis < 3; axis++)
+            gyroData[axis] = gyroADC[axis];
+    }
+}
+
+// **************************************************
+// Simplified IMU based on "Complementary Filter"
+// Inspired by http://starlino.com/imu_guide.html
+//
+// adapted by ziss_dm : http://www.multiwii.com/forum/viewtopic.php?f=8&t=198
+//
+// The following ideas was used in this project:
+// 1) Rotation matrix: http://en.wikipedia.org/wiki/Rotation_matrix
+//
+// Currently Magnetometer uses separate CF which is used only
+// for heading approximation.
+//
+// **************************************************
+
+#define INV_GYR_CMPF_FACTOR   (1.0f / ((float)mcfg.gyro_cmpf_factor + 1.0f))
+#define INV_GYR_CMPFM_FACTOR  (1.0f / ((float)mcfg.gyro_cmpfm_factor + 1.0f))
+
+typedef struct fp_vector {
+    float X;
+    float Y;
+    float Z;
+} t_fp_vector_def;
+
+typedef union {
+    float A[3];
+    t_fp_vector_def V;
+} t_fp_vector;
+
+t_fp_vector EstG;
+
+// Normalize a vector
+void normalizeV(struct fp_vector *src, struct fp_vector *dest)
+{
+    float length;
+
+    length = sqrtf(src->X * src->X + src->Y * src->Y + src->Z * src->Z);
+    if (length != 0) {
+        dest->X = src->X / length;
+        dest->Y = src->Y / length;
+        dest->Z = src->Z / length;
+    }
+}
+
+// Rotate Estimated vector(s) with small angle approximation, according to the gyro data
+void rotateV(struct fp_vector *v, float *delta)
+{
+    struct fp_vector v_tmp = *v;
+
+    // This does a  "proper" matrix rotation using gyro deltas without small-angle approximation
+    float mat[3][3];
+    float cosx, sinx, cosy, siny, cosz, sinz;
+    float coszcosx, coszcosy, sinzcosx, coszsinx, sinzsinx;
+
+    cosx = cosf(delta[ROLL]);
+    sinx = sinf(delta[ROLL]);
+    cosy = cosf(delta[PITCH]);
+    siny = sinf(delta[PITCH]);
+    cosz = cosf(delta[YAW]);
+    sinz = sinf(delta[YAW]);
+
+    coszcosx = cosz * cosx;
+    coszcosy = cosz * cosy;
+    sinzcosx = sinz * cosx;
+    coszsinx = sinx * cosz;
+    sinzsinx = sinx * sinz;
+
+    mat[0][0] = coszcosy;
+    mat[0][1] = -cosy * sinz;
+    mat[0][2] = siny;
+    mat[1][0] = sinzcosx + (coszsinx * siny);
+    mat[1][1] = coszcosx - (sinzsinx * siny);
+    mat[1][2] = -sinx * cosy;
+    mat[2][0] = (sinzsinx) - (coszcosx * siny);
+    mat[2][1] = (coszsinx) + (sinzcosx * siny);
+    mat[2][2] = cosy * cosx;
+
+    v->X = v_tmp.X * mat[0][0] + v_tmp.Y * mat[1][0] + v_tmp.Z * mat[2][0];
+    v->Y = v_tmp.X * mat[0][1] + v_tmp.Y * mat[1][1] + v_tmp.Z * mat[2][1];
+    v->Z = v_tmp.X * mat[0][2] + v_tmp.Y * mat[1][2] + v_tmp.Z * mat[2][2];
+}
+
+int32_t applyDeadband(int32_t value, int32_t deadband)
+{
+    if (abs(value) < deadband) {
+        value = 0;
+    } else if (value > 0) {
+        value -= deadband;
+    } else if (value < 0) {
+        value += 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)
+{
+    static int32_t accZoffset = 0;
+    static float accz_smooth;
+    float rpy[3];
+    t_fp_vector accel_ned;
+
+    // the accel values have to be rotated into the earth frame
+    rpy[0] = -(float)anglerad[ROLL];
+    rpy[1] = -(float)anglerad[PITCH];
+    rpy[2] = -(float)heading * RAD;
+
+    accel_ned.V.X = accSmooth[0];
+    accel_ned.V.Y = accSmooth[1];
+    accel_ned.V.Z = accSmooth[2];
+
+    rotateV(&accel_ned.V, rpy);
+
+    if (cfg.acc_unarmedcal == 1) {
+        if (!f.ARMED) {
+            accZoffset -= accZoffset / 64;
+            accZoffset += accel_ned.V.Z;
+        }
+        accel_ned.V.Z -= accZoffset / 64;  // compensate for gravitation on z-axis
+    } else
+        accel_ned.V.Z -= acc_1G;
+    
+    accz_smooth = accz_smooth + (deltaT / (fc_acc + deltaT)) * (accel_ned.V.Z - accz_smooth); // low pass filter
+
+    // apply Deadband to reduce integration drift and vibration influence
+    accel_ned.V.Z = applyDeadband(lrintf(accz_smooth), cfg.accz_deadband);
+    accel_ned.V.X = applyDeadband(lrintf(accel_ned.V.X), cfg.accxy_deadband);
+    accel_ned.V.Y = applyDeadband(lrintf(accel_ned.V.Y), cfg.accxy_deadband);
+
+    // sum up Values for later integration to get velocity and distance
+    accTimeSum += deltaT;
+    accSumCount++;
+
+    accSum[X] += lrintf(accel_ned.V.X);
+    accSum[Y] += lrintf(accel_ned.V.Y);
+    accSum[Z] += lrintf(accel_ned.V.Z);
+}
+
+void accSum_reset(void)
+{
+    accSum[0] = 0;
+    accSum[1] = 0;
+    accSum[2] = 0;
+    accSumCount = 0;
+    accTimeSum = 0;
+}
+
+// baseflight calculation by Luggi09 originates from arducopter
+static int16_t calculateHeading(t_fp_vector *vec)
+{
+    int16_t head;
+
+    float cosineRoll = cosf(anglerad[ROLL]);
+    float sineRoll = sinf(anglerad[ROLL]);
+    float cosinePitch = cosf(anglerad[PITCH]);
+    float sinePitch = sinf(anglerad[PITCH]);
+    float Xh = vec->A[X] * cosinePitch + vec->A[Y] * sineRoll * sinePitch + vec->A[Z] * sinePitch * cosineRoll;
+    float Yh = vec->A[Y] * cosineRoll - vec->A[Z] * sineRoll;
+    float hd = (atan2f(Yh, Xh) * 1800.0f / M_PI + magneticDeclination) / 10.0f;
+    head = lrintf(hd);
+    if (head < 0)
+        head += 360;
+
+    return head;
+}
+
+static void getEstimatedAttitude(void)
+{
+    uint32_t axis;
+    int32_t accMag = 0;
+    static t_fp_vector EstM;
+    static t_fp_vector EstN = { .A = { 1000.0f, 0.0f, 0.0f } };
+    static float accLPF[3];
+    static uint32_t previousT;
+    uint32_t currentT = micros();
+    uint32_t deltaT;
+    float scale, deltaGyroAngle[3];
+    deltaT = currentT - previousT;
+    scale = deltaT * gyro.scale;
+    previousT = currentT;
+
+    // Initialization
+    for (axis = 0; axis < 3; axis++) {
+        deltaGyroAngle[axis] = gyroADC[axis] * scale;
+        if (cfg.acc_lpf_factor > 0) {
+            accLPF[axis] = accLPF[axis] * (1.0f - (1.0f / cfg.acc_lpf_factor)) + accADC[axis] * (1.0f / cfg.acc_lpf_factor);
+            accSmooth[axis] = accLPF[axis];
+        } else {
+            accSmooth[axis] = accADC[axis];
+        }
+        accMag += (int32_t)accSmooth[axis] * accSmooth[axis];
+    }
+    accMag = accMag * 100 / ((int32_t)acc_1G * acc_1G);
+
+    rotateV(&EstG.V, deltaGyroAngle);
+    if (sensors(SENSOR_MAG))
+        rotateV(&EstM.V, deltaGyroAngle);
+    else
+        rotateV(&EstN.V, deltaGyroAngle);
+
+    // Apply complimentary filter (Gyro drift correction)
+    // If accel magnitude >1.15G or <0.85G and ACC vector outside of the limit range => we neutralize the effect of accelerometers in the angle estimation.
+    // To do that, we just skip filter, as EstV already rotated by Gyro
+    if (72 < (uint16_t)accMag && (uint16_t)accMag < 133) {
+        for (axis = 0; axis < 3; axis++)
+            EstG.A[axis] = (EstG.A[axis] * (float)mcfg.gyro_cmpf_factor + accSmooth[axis]) * INV_GYR_CMPF_FACTOR;
+    }
+
+    if (sensors(SENSOR_MAG)) {
+        for (axis = 0; axis < 3; axis++)
+            EstM.A[axis] = (EstM.A[axis] * (float)mcfg.gyro_cmpfm_factor + magADC[axis]) * INV_GYR_CMPFM_FACTOR;
+    }
+
+   if (EstG.A[Z] > accZ_25deg)
+        f.SMALL_ANGLES_25 = 1;
+    else
+        f.SMALL_ANGLES_25 = 0;
+
+    // Attitude of the estimated vector
+    anglerad[ROLL] = atan2f(EstG.V.Y, EstG.V.Z);
+    anglerad[PITCH] = atan2f(-EstG.V.X, sqrtf(EstG.V.Y * EstG.V.Y + EstG.V.Z * EstG.V.Z));
+    angle[ROLL] = lrintf(anglerad[ROLL] * (1800.0f / M_PI));
+    angle[PITCH] = lrintf(anglerad[PITCH] * (1800.0f / M_PI));
+
+    if (sensors(SENSOR_MAG))
+        heading = calculateHeading(&EstM);
+    else
+        heading = calculateHeading(&EstN);
+
+    acc_calc(deltaT); // rotate acc vector into earth frame
+
+    if (cfg.throttle_angle_correction) {
+        int cosZ = ((int32_t)(EstG.V.Z * 100.0f)) / acc_1G;
+        throttleAngleCorrection = cfg.throttle_angle_correction * constrain(100 - cosZ, 0, 100) / 8;
+    }
+}
+
+#ifdef BARO
+#define UPDATE_INTERVAL 25000   // 40hz update rate (20hz LPF on acc)
+
+int getEstimatedAltitude(void)
+{
+    static uint32_t previousT;
+    uint32_t currentT = micros();
+    uint32_t dTime;
+    int32_t error;
+    int32_t baroVel;
+    int32_t vel_tmp;
+    int32_t BaroAlt_tmp;
+    int32_t setVel;
+    float dt;
+    float vel_acc;
+    float accZ_tmp;
+    static float accZ_old = 0.0f;
+    static float vel = 0.0f;
+    static float accAlt = 0.0f;
+    static int32_t lastBaroAlt;
+    static int32_t baroGroundAltitude = 0;
+    static int32_t baroGroundPressure = 0;
+
+    dTime = currentT - previousT;
+    if (dTime < UPDATE_INTERVAL)
+        return 0;
+    previousT = currentT;
+
+    if (calibratingB > 0) {
+        baroGroundPressure -= baroGroundPressure / 8;
+        baroGroundPressure += baroPressureSum / (cfg.baro_tab_size - 1);
+        baroGroundAltitude = (1.0f - powf((baroGroundPressure / 8) / 101325.0f, 0.190295f)) * 4433000.0f; 
+        
+        vel = 0;
+        accAlt = 0;
+        calibratingB--;
+    }
+
+    // calculates height from ground via baro readings
+    // see: https://github.com/diydrones/ardupilot/blob/master/libraries/AP_Baro/AP_Baro.cpp#L140
+    BaroAlt_tmp = lrintf((1.0f - powf((float)(baroPressureSum / (cfg.baro_tab_size - 1)) / 101325.0f, 0.190295f)) * 4433000.0f); // in cm
+    BaroAlt_tmp -= baroGroundAltitude;
+    BaroAlt = lrintf((float)BaroAlt * cfg.baro_noise_lpf + (float)BaroAlt_tmp * (1.0f - cfg.baro_noise_lpf)); // additional LPF to reduce baro noise
+
+    dt = accTimeSum * 1e-6f; // delta acc reading time in seconds
+
+    // Integrator - velocity, cm/sec
+    accZ_tmp = (float)accSum[2] / (float)accSumCount;
+    vel_acc = accZ_tmp * accVelScale * (float)accTimeSum;
+
+    // Integrator - Altitude in cm
+    accAlt += (vel_acc * 0.5f) * dt  + vel * dt;                                        // integrate velocity to get distance (x= a/2 * t^2)
+    accAlt = accAlt * cfg.baro_cf_alt + (float) BaroAlt *(1.0f - cfg.baro_cf_alt);      // complementary filter for Altitude estimation (baro & acc)
+    EstAlt = accAlt;
+    vel += vel_acc;
+
+#if 0
+    debug[0] = accSum[2] / accSumCount; // acceleration
+    debug[1] = vel;                     // velocity
+    debug[2] = accAlt;                  // height
+#endif
+
+    accSum_reset();
+
+    baroVel = (BaroAlt - lastBaroAlt) * 1000000.0f / dTime;
+    lastBaroAlt = BaroAlt;
+
+    baroVel = constrain(baroVel, -300, 300);    // constrain baro velocity +/- 300cm/s
+    baroVel = applyDeadband(baroVel, 10);       // to reduce noise near zero
+
+    // apply Complimentary Filter to keep the calculated velocity based on baro velocity (i.e. near real velocity).
+    // By using CF it's possible to correct the drift of integrated accZ (velocity) without loosing the phase, i.e without delay
+    vel = vel * cfg.baro_cf_vel + baroVel * (1 - cfg.baro_cf_vel);
+
+    // set vario
+    vel_tmp = lrintf(vel);
+    vel_tmp = applyDeadband(vel_tmp, 5);
+    vario = vel_tmp;
+
+    // Altitude P-Controller
+    error = constrain(AltHold - EstAlt, -500, 500);
+    error = applyDeadband(error, 10);       // remove small P parametr to reduce noise near zero position
+    setVel = constrain((cfg.P8[PIDALT] * error / 128), -300, +300); // limit velocity to +/- 3 m/s
+
+    // Velocity PID-Controller
+    // P
+    error = setVel - lrintf(vel);
+    BaroPID = constrain((cfg.P8[PIDVEL] * error / 32), -300, +300);
+
+    // I
+    errorAltitudeI += (cfg.I8[PIDVEL] * error) / 8;
+    errorAltitudeI = constrain(errorAltitudeI, -(1024 * 200), (1024 * 200));
+    BaroPID += errorAltitudeI / 1024;     // I in range +/-200
+
+    // D
+    accZ_old = accZ_tmp;
+    BaroPID -= constrain(cfg.D8[PIDVEL] * (accZ_tmp + accZ_old) / 64, -150, 150);
+
+    return 1;
+}
+#endif /* BARO */