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/*

Copyright 2008, by Killagreg

This program (files mm3.c and mm3.h) is free software; you can redistribute it and/or modify

it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation;

either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;

without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License

along with this program. If not, see <http://www.gnu.org/licenses/>.

Please note: The original implementation was done by Niklas Nold.

All the other files for the project "Mikrokopter" by H. Buss are under the license (license_buss.txt) published by www.mikrokopter.de

*/

#include <stdlib.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include "mm3.h"

#include "main.h"

#include "mymath.h"

#include "fc.h"

#include "timer0.h"

#include "rc.h"

#include "eeprom.h"

#define MAX_AXIS_VALUE          500

typedef struct

{

        uint8_t STATE;

        uint16_t DRDY;

        uint8_t AXIS;

        int16_t x_axis;

        int16_t y_axis;

        int16_t z_axis;

} MM3_working_t;

// MM3 State Machine

#define MM3_STATE_RESET                         0

#define MM3_STATE_START_TRANSFER        1

#define MM3_STATE_WAIT_DRDY                     2

#define MM3_STATE_DRDY                          3

#define MM3_STATE_BYTE2                         4

#define MM3_X_AXIS              0x01

#define MM3_Y_AXIS              0x02

#define MM3_Z_AXIS              0x03

#define MM3_PERIOD_32   0x00

#define MM3_PERIOD_64   0x10

#define MM3_PERIOD_128  0x20

#define MM3_PERIOD_256  0x30

#define MM3_PERIOD_512  0x40

#define MM3_PERIOD_1024 0x50

#define MM3_PERIOD_2048 0x60

#define MM3_PERIOD_4096 0x70

MM3_calib_t MM3_calib;

volatile MM3_working_t MM3;

volatile uint8_t MM3_Timeout = 0;

/*********************************************/

/*  Initialize Interface to MM3 Compass      */

/*********************************************/

void MM3_Init(void)

{

        uint8_t sreg = SREG;

        cli();

        // Configure Pins for SPI

        // set SCK (PB7), MOSI (PB5) as output

        DDRB |= (1<<DDB7)|(1<<DDB5);

        // set MISO (PB6) as input

        DDRB &= ~(1<<DDB6);

        // Output Pins PC4->MM3_SS ,PC5->MM3_RESET

        DDRC |= (1<<DDC4)|(1<<DDC5);

        // set pins permanent to low

        PORTC &= ~((1<<PORTC4)|(1<<PORTC5));

        // Initialize SPI-Interface

        // Enable interrupt (SPIE=1)

        // Enable SPI bus (SPE=1)

        // MSB transmitted first (DORD = 0)

        // Master SPI Mode (MSTR=1)

        // Clock polarity low whn idle (CPOL=0)

        // clock phase sample at leading edge (CPHA=0)

        // clock rate = SYSCLK/128 (SPI2X=0, SPR1=1, SPR0=1) 20MHz/128 = 156.25kHz

        SPCR = (1<<SPIE)|(1<<SPE)|(0<<DORD)|(1<<MSTR)|(0<<CPOL)|(0<<CPHA)|(1<<SPR1)|(1<<SPR0);

        SPSR &= ~(1<<SPI2X);

    // Init Statemachine

        MM3.AXIS = MM3_X_AXIS;

        MM3.STATE = MM3_STATE_RESET;

        // Read calibration from EEprom

        MM3_calib.X_off = (int8_t)GetParamByte(PID_MM3_X_OFF);

        MM3_calib.Y_off = (int8_t)GetParamByte(PID_MM3_Y_OFF);

        MM3_calib.Z_off = (int8_t)GetParamByte(PID_MM3_Z_OFF);

        MM3_calib.X_range = (int16_t)GetParamWord(PID_MM3_X_RANGE);

        MM3_calib.Y_range = (int16_t)GetParamWord(PID_MM3_Y_RANGE);

        MM3_calib.Z_range = (int16_t)GetParamWord(PID_MM3_Z_RANGE);

        MM3_Timeout = 0;

        SREG = sreg;

}

/*********************************************/

/*  Get Data from MM3                        */

/*********************************************/

void MM3_Update(void) // called every 102.4 µs by timer 0 ISR

{

        switch (MM3.STATE)

        {

        case MM3_STATE_RESET:

                PORTC &= ~(1<<PORTC4);  // select slave

                PORTC |= (1<<PORTC5);   // PC5 to High, MM3 Reset

                MM3.STATE = MM3_STATE_START_TRANSFER;

                return;

        case MM3_STATE_START_TRANSFER:

                PORTC &= ~(1<<PORTC5);  // PC4 auf Low (was 102.4 µs at high level)

                // write to SPDR triggers automatically the transfer MOSI MISO

                // MM3 Period, + AXIS code

                switch(MM3.AXIS)

                {

                case MM3_X_AXIS:

                        SPDR = MM3_PERIOD_256 + MM3_X_AXIS;

                        break;

                case MM3_Y_AXIS:

                        SPDR = MM3_PERIOD_256 + MM3_Y_AXIS;

                        break;

                case MM3_Z_AXIS:

                        SPDR = MM3_PERIOD_256 + MM3_Z_AXIS;

                        break;

                default:

                        MM3.AXIS = MM3_X_AXIS;

                        MM3.STATE = MM3_STATE_RESET;

                        return;

                }

                // DRDY line is not connected, therefore

                // wait before reading data back

                MM3.DRDY = SetDelay(8); // wait 8ms for data ready

                MM3.STATE = MM3_STATE_WAIT_DRDY;

                return;

        case MM3_STATE_WAIT_DRDY:

                if (CheckDelay(MM3.DRDY))

                {

                        // write something into SPDR to trigger data reading

                        SPDR = 0x00;

                        MM3.STATE = MM3_STATE_DRDY;

                }

                return;

        }

}

/*********************************************/

/*  Interrupt SPI transfer complete          */

/*********************************************/

ISR(SPI_STC_vect)

{

        static int8_t tmp;

        int16_t value;

        switch (MM3.STATE)

        {

        // 1st byte received

        case MM3_STATE_DRDY:

                tmp = SPDR;     // store 1st byte

                SPDR = 0x00;    // trigger transfer of 2nd byte

                MM3.STATE = MM3_STATE_BYTE2;

                return;

        case MM3_STATE_BYTE2:           // 2nd byte received

                value = (int16_t)tmp;   // combine the 1st and 2nd byte to a word

                value <<= 8;            // shift 1st byte to MSB-Position

                value |= (int16_t)SPDR; // add 2nd byte

                if(abs(value) < MAX_AXIS_VALUE)         // ignore spikes

                {

                        switch (MM3.AXIS)

                        {

                        case MM3_X_AXIS:

                                MM3.x_axis = value;

                                MM3.AXIS = MM3_Y_AXIS;

                                break;

                        case MM3_Y_AXIS:

                                MM3.y_axis = value;

                                MM3.AXIS = MM3_Z_AXIS;

                                break;

                        case MM3_Z_AXIS:

                                MM3.z_axis = value;

                                MM3.AXIS = MM3_X_AXIS;

                                break;

                        default:

                                MM3.AXIS = MM3_X_AXIS;

                                break;

                        }

                }

                PORTC |= (1<<PORTC4); // deselect slave

                MM3.STATE = MM3_STATE_RESET;

                // Update timeout is called every 102.4 µs.

                // It takes 2 cycles to write a measurement data request for one axis and

                // at at least 8 ms / 102.4 µs = 79 cycles to read the requested data back.

                // I.e. 81 cycles * 102.4 µs = 8.3ms per axis.

                // The two function accessing the MM3 Data - MM3_Calibrate() and MM3_Heading() -

                // decremtent the MM3_Timeout every 100 ms.

                // incrementing the counter by 1 every 8.3 ms is sufficient to avoid a timeout.

                if ((MM3.x_axis != MM3.y_axis) || (MM3.x_axis != MM3.z_axis) || (MM3.y_axis != MM3.z_axis))

                {       // if all axis measurements give diffrent readings the data should be valid

                        if(MM3_Timeout < 20) MM3_Timeout++;

                }

                else // something is very strange here

                {

                        if(MM3_Timeout ) MM3_Timeout--;

                }

                return;

        default:

                return;

        }

}

/*********************************************/

/*  Calibrate Compass                        */

/*********************************************/

void MM3_Calibrate(void)

{

        int16_t x_min = 0, x_max = 0, y_min = 0, y_max = 0, z_min = 0, z_max = 0;

        uint8_t measurement = 50, beeper = 0;

        uint16_t timer;

        GRN_ON;

        ROT_OFF;

        // get maximum and minimum reading of all axis

        while (measurement)

        {

                if (MM3.x_axis > x_max) x_max = MM3.x_axis;

                else if (MM3.x_axis < x_min) x_min = MM3.x_axis;

                if (MM3.y_axis > y_max) y_max = MM3.y_axis;

                else if (MM3.y_axis < y_min) y_min = MM3.y_axis;

                if (MM3.z_axis > z_max) z_max = MM3.z_axis;

                else if (MM3.z_axis < z_min) z_min = MM3.z_axis;

                if (!beeper)

                {

                        ROT_FLASH;

                        GRN_FLASH;

                        BeepTime = 50;

                        beeper = 50;

                }

                beeper--;

                // loop with period of 10 ms / 100 Hz

                timer = SetDelay(10);

                while(!CheckDelay(timer));

                // If thrust is less than 100, stop calibration with a delay of 0.5 seconds

                if (PPM_in[ParamSet.ChannelAssignment[CH_THRUST]] < 100) measurement--;

        }

        // Rage of all axis

        MM3_calib.X_range = (x_max - x_min);

        MM3_calib.Y_range = (y_max - y_min);

        MM3_calib.Z_range = (z_max - z_min);

        // Offset of all axis

        MM3_calib.X_off = (x_max + x_min) / 2;

        MM3_calib.Y_off = (y_max + y_min) / 2;

        MM3_calib.Z_off = (z_max + z_min) / 2;

        // save to EEProm

        SetParamByte(PID_MM3_X_OFF,   (uint8_t)MM3_calib.X_off);

        SetParamByte(PID_MM3_Y_OFF,   (uint8_t)MM3_calib.Y_off);

        SetParamByte(PID_MM3_Z_OFF,   (uint8_t)MM3_calib.Z_off);

        SetParamWord(PID_MM3_X_RANGE, (uint16_t)MM3_calib.X_range);

        SetParamWord(PID_MM3_Y_RANGE, (uint16_t)MM3_calib.Y_range);

        SetParamWord(PID_MM3_Z_RANGE, (uint16_t)MM3_calib.Z_range);

}

/*********************************************/

/*  Calculate north direction (heading)      */

/*********************************************/

int16_t MM3_Heading(void)

{

        int32_t sin_pitch, cos_pitch, sin_roll, cos_roll, sin_yaw, cos_yaw;

        int32_t  Hx, Hy, Hz, Hx_corr, Hy_corr;

        int16_t angle;

        uint16_t div_factor;

        int16_t heading;

        if (MM3_Timeout)

        {

                // Offset correction and normalization (values of H are +/- 512)

                Hx = (((int32_t)(MM3.x_axis - MM3_calib.X_off)) * 1024) / (int32_t)MM3_calib.X_range;

                Hy = (((int32_t)(MM3.y_axis - MM3_calib.Y_off)) * 1024) / (int32_t)MM3_calib.Y_range;

                Hz = (((int32_t)(MM3.z_axis - MM3_calib.Z_off)) * 1024) / (int32_t)MM3_calib.Z_range;

                // Compensate the angle of the MM3-arrow to the head of the MK by a yaw rotation transformation

                // assuming the MM3 board is mounted parallel to the frame.

                // User Param 4 is used to define the positive angle from the MM3-arrow to the MK heading

                // in a top view counter clockwise direction.

                // North is in opposite direction of the small arrow on the MM3 board.

                // Therefore 180 deg must be added to that angle.

                angle = ((int16_t)ParamSet.UserParam4 + 180);

                // wrap angle to interval of 0°- 359°

                angle += 360;

                angle %= 360;

                sin_yaw = (int32_t)(c_sin_8192(angle));

                cos_yaw = (int32_t)(c_cos_8192(angle));

                Hx_corr = Hx;

                Hy_corr = Hy;

                // rotate

                Hx = (Hx_corr * cos_yaw - Hy_corr  * sin_yaw) / 8192;

                Hy = (Hx_corr * sin_yaw + Hy_corr  * cos_yaw) / 8192;

                // tilt compensation

                // calibration factor for transforming Gyro Integrals to angular degrees

                div_factor = (uint16_t)ParamSet.UserParam3 * 8;

                // calculate sinus cosinus of pitch and tilt angle

                angle = (IntegralPitch/div_factor);

                sin_pitch = (int32_t)(c_sin_8192(angle));

                cos_pitch = (int32_t)(c_cos_8192(angle));

                angle = (IntegralRoll/div_factor);

                sin_roll = (int32_t)(c_sin_8192(angle));

                cos_roll = (int32_t)(c_cos_8192(angle));

                Hx_corr = Hx * cos_pitch;

                Hx_corr -= Hz * sin_pitch;

                Hx_corr /= 8192;

                Hy_corr = Hy * cos_roll;

                Hy_corr += Hz * sin_roll;

                Hy_corr /= 8192;

                // calculate Heading

                heading = c_atan2(Hy_corr, Hx_corr);

                // atan returns angular range from -180 deg to 180 deg in counter clockwise notation

                // but the compass course is defined in a range from 0 deg to 360 deg clockwise notation.

                if (heading < 0) heading = -heading;

                else heading = 360 - heading;

        }

        else // MM3_Timeout = 0 i.e now new data from external board

        {

                if(!BeepTime) BeepTime = 100; // make noise to signal the compass problem

                heading = -1;

        }

return heading;

}