Subversion Repositories FlightCtrl

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <stdlib.h>

#include "analog.h"
#include "attitude.h"
#include "sensors.h"
#include "printf_P.h"
#include "isqrt.h"

// for Delay functions
#include "timer0.h"

// For reading and writing acc. meter offsets.
#include "eeprom.h"

// For debugOut
#include "output.h"

// set ADC enable & ADC Start Conversion & ADC Interrupt Enable bit
#define startADC() (ADCSRA |= (1<<ADEN)|(1<<ADSC)|(1<<ADIE))

const char* recal = ", recalibration needed.";

/*
 * For each A/D conversion cycle, each analog channel is sampled a number of times
 * (see array channelsForStates), and the results for each channel are summed.
 * Here are those for the gyros and the acc. meters. They are not zero-offset.
 * They are exported in the analog.h file - but please do not use them! The only
 * reason for the export is that the ENC-03_FC1.3 modules needs them for calibrating
 * the offsets with the DAC.
 */
volatile uint16_t sensorInputs[8];


/*
 * These 4 exported variables are zero-offset. The "PID" ones are used
 * in the attitude control as rotation rates. The "ATT" ones are for
 * integration to angles.
 */
int16_t gyro_PID[3];
int16_t gyro_ATT[3];
int16_t gyroD[3];
int16_t gyroDWindow[3][GYRO_D_WINDOW_LENGTH];
uint8_t gyroDWindowIdx = 0;

/*
 * Offset values. These are the raw gyro and acc. meter sums when the copter is
 * standing still. They are used for adjusting the gyro and acc. meter values
 * to be centered on zero.
 */
sensorOffset_t gyroOffset;
uint16_t airpressureOffset;

/*
 * In the MK coordinate system, nose-down is positive and left-roll is positive.
 * If a sensor is used in an orientation where one but not both of the axes has
 * an opposite sign, PR_ORIENTATION_REVERSED is set to 1 (true).
 * Transform:
 * pitch <- pp*pitch + pr*roll
 * roll  <- rp*pitch + rr*roll
 * Not reversed, GYRO_QUADRANT:
 * 0: pp=1, pr=0, rp=0, rr=1  // 0    degrees
 * 1: pp=1, pr=-1,rp=1, rr=1  // +45  degrees
 * 2: pp=0, pr=-1,rp=1, rr=0  // +90  degrees
 * 3: pp=-1,pr=-1,rp=1, rr=1  // +135 degrees
 * 4: pp=-1,pr=0, rp=0, rr=-1 // +180 degrees
 * 5: pp=-1,pr=1, rp=-1,rr=-1 // +225 degrees
 * 6: pp=0, pr=1, rp=-1,rr=0  // +270 degrees
 * 7: pp=1, pr=1, rp=-1,rr=1  // +315 degrees
 * Reversed, GYRO_QUADRANT:
 * 0: pp=-1,pr=0, rp=0, rr=1  // 0    degrees with pitch reversed
 * 1: pp=-1,pr=-1,rp=-1,rr=1  // +45  degrees with pitch reversed
 * 2: pp=0, pr=-1,rp=-1,rr=0  // +90  degrees with pitch reversed
 * 3: pp=1, pr=-1,rp=-1,rr=1  // +135 degrees with pitch reversed
 * 4: pp=1, pr=0, rp=0, rr=-1 // +180 degrees with pitch reversed
 * 5: pp=1, pr=1, rp=1, rr=-1 // +225 degrees with pitch reversed
 * 6: pp=0, pr=1, rp=1, rr=0  // +270 degrees with pitch reversed
 * 7: pp=-1,pr=1, rp=1, rr=1  // +315 degrees with pitch reversed
 */

void rotate(int16_t* result, uint8_t quadrant, uint8_t reversePR, uint8_t reverseYaw) {
  static const int8_t rotationTab[] = {1,1,0,-1,-1,-1,0,1};
  // Pitch to Pitch part
  int8_t xx = reversePR ? rotationTab[(quadrant+4)%8] : rotationTab[quadrant];
  // Roll to Pitch part
  int8_t xy = rotationTab[(quadrant+2)%8];
  // Pitch to Roll part
  int8_t yx = reversePR ? rotationTab[(quadrant+2)%8] : rotationTab[(quadrant+6)%8];
  // Roll to Roll part
  int8_t yy = rotationTab[quadrant];

  int16_t xIn = result[0];
  result[0] = xx*xIn + xy*result[1];
  result[1] = yx*xIn + yy*result[1];
 
  if (quadrant & 1) {
        // A rotation was used above, where the factors were too large by sqrt(2).
        // So, we multiply by 2^n/sqt(2) and right shift n bits, as to divide by sqrt(2).
        // A suitable value for n: Sample is 11 bits. After transformation it is the sum
        // of 2 11 bit numbers, so 12 bits. We have 4 bits left...
        result[0] = (result[0]*11) >> 4;
        result[1] = (result[1]*11) >> 4;
  }

  if (reverseYaw)
    result[3] =-result[3];
}

/*
 * Airspeed
 */
uint16_t simpleAirPressure;

/*
 * Battery voltage, in units of: 1k/11k / 3V * 1024 = 31.03 per volt.
 * That is divided by 3 below, for a final 10.34 per volt.
 * So the initial value of 100 is for 9.7 volts.
 */
uint16_t UBat = 100;
uint16_t airspeedVelocity = 0;

/*
 * Control and status.
 */
volatile uint8_t analogDataReady = 1;

/*
 * Experiment: Measuring vibration-induced sensor noise.
 */
uint16_t gyroNoisePeak[3];

volatile uint8_t adState;
volatile uint8_t adChannel;

// ADC channels
#define AD_GYRO_YAW       0
#define AD_GYRO_ROLL      1
#define AD_GYRO_PITCH     2
#define AD_AIRPRESSURE    3
#define AD_UBAT           4
#define AD_ACC_Z          5
#define AD_ACC_ROLL       6
#define AD_ACC_PITCH      7

/*
 * Table of AD converter inputs for each state.
 * The number of samples summed for each channel is equal to
 * the number of times the channel appears in the array.
 * The max. number of samples that can be taken in 2 ms is:
 * 20e6 / 128 / 13 / (1/2e-3) = 24. Since the main control
 * loop needs a little time between reading AD values and
 * re-enabling ADC, the real limit is (how much?) lower.
 * The acc. sensor is sampled even if not used - or installed
 * at all. The cost is not significant.
 */

const uint8_t channelsForStates[] PROGMEM = {
  AD_GYRO_PITCH,
  AD_GYRO_ROLL,
  AD_GYRO_YAW,

  AD_AIRPRESSURE,

  AD_GYRO_PITCH,
  AD_GYRO_ROLL,
  AD_GYRO_YAW,

  AD_UBAT,

  AD_GYRO_PITCH,
  AD_GYRO_ROLL,
  AD_GYRO_YAW,
 
  AD_AIRPRESSURE,
 
  AD_GYRO_PITCH,
  AD_GYRO_ROLL,
  AD_GYRO_YAW
};

// Feature removed. Could be reintroduced later - but should work for all gyro types then.
// uint8_t GyroDefectPitch = 0, GyroDefectRoll = 0, GyroDefectYaw = 0;

void analog_init(void) {
        uint8_t sreg = SREG;
        // disable all interrupts before reconfiguration
        cli();

        //ADC0 ... ADC7 is connected to PortA pin 0 ... 7
        DDRA = 0x00;
        PORTA = 0x00;
        // Digital Input Disable Register 0
        // Disable digital input buffer for analog adc_channel pins
        DIDR0 = 0xFF;
        // external reference, adjust data to the right
        ADMUX &= ~((1<<REFS1)|(1<<REFS0)|(1<<ADLAR));
        // set muxer to ADC adc_channel 0 (0 to 7 is a valid choice)
        ADMUX = (ADMUX & 0xE0);
        //Set ADC Control and Status Register A
        //Auto Trigger Enable, Prescaler Select Bits to Division Factor 128, i.e. ADC clock = SYSCKL/128 = 156.25 kHz
        ADCSRA = (1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);
        //Set ADC Control and Status Register B
        //Trigger Source to Free Running Mode
        ADCSRB &= ~((1<<ADTS2)|(1<<ADTS1)|(1<<ADTS0));

        startAnalogConversionCycle();

        // restore global interrupt flags
        SREG = sreg;
}

uint16_t rawGyroValue(uint8_t axis) {
        return sensorInputs[AD_GYRO_PITCH-axis];
}

/*
uint16_t rawAccValue(uint8_t axis) {
        return sensorInputs[AD_ACC_PITCH-axis];
}
*/

void measureNoise(const int16_t sensor,
                volatile uint16_t* const noiseMeasurement, const uint8_t damping) {
        if (sensor > (int16_t) (*noiseMeasurement)) {
                *noiseMeasurement = sensor;
        } else if (-sensor > (int16_t) (*noiseMeasurement)) {
                *noiseMeasurement = -sensor;
        } else if (*noiseMeasurement > damping) {
                *noiseMeasurement -= damping;
        } else {
                *noiseMeasurement = 0;
        }
}

void startAnalogConversionCycle(void) {
  analogDataReady = 0;

  // Stop the sampling. Cycle is over.
  for (uint8_t i = 0; i < 8; i++) {
    sensorInputs[i] = 0;
  }
  adState = 0;
  adChannel = AD_GYRO_PITCH;
  ADMUX = (ADMUX & 0xE0) | adChannel;
  startADC();
}

/*****************************************************
 * Interrupt Service Routine for ADC
 * Runs at 312.5 kHz or 3.2 �s. When all states are
 * processed further conversions are stopped.
 *****************************************************/
ISR(ADC_vect) {
  sensorInputs[adChannel] += ADC;
  // set up for next state.
  adState++;
  if (adState < sizeof(channelsForStates)) {
    adChannel = pgm_read_byte(&channelsForStates[adState]);
    // set adc muxer to next adChannel
    ADMUX = (ADMUX & 0xE0) | adChannel;
    // after full cycle stop further interrupts
    startADC();
  } else {
    analogDataReady = 1;
    // do not restart ADC converter.
  }
}

/*
void measureGyroActivity(int16_t newValue) {
  gyroActivity += (uint32_t)((int32_t)newValue * newValue);
}

#define GADAMPING 6
void dampenGyroActivity(void) {
  static uint8_t cnt = 0;
  if (++cnt >= IMUConfig.gyroActivityDamping) {
    cnt = 0;
    gyroActivity *= (uint32_t)((1L<<GADAMPING)-1);
    gyroActivity >>= GADAMPING;
  }
}
*/

void analog_updateGyros(void) {
  // for various filters...
  int16_t tempOffsetGyro[3], tempGyro;
 
  debugOut.digital[0] &= ~DEBUG_SENSORLIMIT;

  for (uint8_t axis=0; axis<3; axis++) {
    tempGyro = rawGyroValue(axis);
    /*
     * Process the gyro data for the PID controller.
     */
    // 1) Extrapolate: Near the ends of the range, we boost the input significantly. This simulates a
    //    gyro with a wider range, and helps counter saturation at full control.
   
    if (staticParams.bitConfig & CFG_GYRO_SATURATION_PREVENTION) {
      if (tempGyro < SENSOR_MIN) {
                debugOut.digital[0] |= DEBUG_SENSORLIMIT;
                tempGyro = tempGyro * EXTRAPOLATION_SLOPE - EXTRAPOLATION_LIMIT;
      } else if (tempGyro > SENSOR_MAX) {
                debugOut.digital[0] |= DEBUG_SENSORLIMIT;
                tempGyro = (tempGyro - SENSOR_MAX) * EXTRAPOLATION_SLOPE + SENSOR_MAX;
      }
    }

    // 2) Apply sign and offset, scale before filtering.
    tempOffsetGyro[axis] = (tempGyro - gyroOffset.offsets[axis]);
  }

  // 2.1: Transform axes.
  rotate(tempOffsetGyro, IMUConfig.gyroQuadrant, IMUConfig.imuReversedFlags & IMU_REVERSE_GYRO_PR, IMUConfig.imuReversedFlags & IMU_REVERSE_GYRO_YAW);

  for (uint8_t axis=0; axis<3; axis++) {
        // 3) Filter.
    tempOffsetGyro[axis] = (gyro_PID[axis] * (IMUConfig.gyroPIDFilterConstant - 1) + tempOffsetGyro[axis]) / IMUConfig.gyroPIDFilterConstant;

    // 4) Measure noise.
    measureNoise(tempOffsetGyro[axis], &gyroNoisePeak[axis], GYRO_NOISE_MEASUREMENT_DAMPING);

    // 5) Differential measurement.
    // gyroD[axis] = (gyroD[axis] * (staticParams.gyroDFilterConstant - 1) + (tempOffsetGyro[axis] - gyro_PID[axis])) / staticParams.gyroDFilterConstant;
    int16_t diff = tempOffsetGyro[axis] - gyro_PID[axis];
    gyroD[axis] -= gyroDWindow[axis][gyroDWindowIdx];
    gyroD[axis] += diff;
    gyroDWindow[axis][gyroDWindowIdx] = diff;

    // 6) Done.
    gyro_PID[axis] = tempOffsetGyro[axis];

    // Prepare tempOffsetGyro for next calculation below...
    tempOffsetGyro[axis] = (rawGyroValue(axis) - gyroOffset.offsets[axis]);
  }

  /*
   * Now process the data for attitude angles.
   */
  rotate(tempOffsetGyro, IMUConfig.gyroQuadrant, IMUConfig.imuReversedFlags & IMU_REVERSE_GYRO_PR, IMUConfig.imuReversedFlags & IMU_REVERSE_GYRO_YAW);

  // dampenGyroActivity();
  gyro_ATT[PITCH] = tempOffsetGyro[PITCH];
  gyro_ATT[ROLL] = tempOffsetGyro[ROLL];
  gyro_ATT[YAW] = tempOffsetGyro[YAW];

  if (++gyroDWindowIdx >= IMUConfig.gyroDWindowLength) {
      gyroDWindowIdx = 0;
  }
}

// probably wanna aim at 1/10 m/s/unit.
#define LOG_AIRSPEED_FACTOR 2

void analog_updateAirspeed(void) {
  uint16_t rawAirPressure = sensorInputs[AD_AIRPRESSURE];
  int16_t temp = rawAirPressure - airpressureOffset;
  if (temp<0) temp = 0;
  simpleAirPressure = temp;
  airspeedVelocity = (staticParams.airspeedCorrection * isqrt16(simpleAirPressure)) >> LOG_AIRSPEED_FACTOR;
}

void analog_updateBatteryVoltage(void) {
  // Battery. The measured value is: (V * 1k/11k)/3v * 1024 = 31.03 counts per volt (max. measurable is 33v).
  // This is divided by 3 --> 10.34 counts per volt.
  UBat = (3 * UBat + sensorInputs[AD_UBAT] / 3) / 4;
}

void analog_update(void) {
  analog_updateGyros();
  // analog_updateAccelerometers();
  analog_updateAirspeed();
  analog_updateBatteryVoltage();
#ifdef USE_MK3MAG
  magneticHeading = volatileMagneticHeading;
#endif
}

void analog_setNeutral() {
  gyro_init();
 
  if (gyroOffset_readFromEEProm()) {
    printf("gyro offsets invalid%s",recal);
    gyroOffset.offsets[PITCH] = gyroOffset.offsets[ROLL] = 512 * GYRO_OVERSAMPLING;
    gyroOffset.offsets[YAW] = 512 * GYRO_OVERSAMPLING;
  }

  // Noise is relative to offset. So, reset noise measurements when changing offsets.
  for (uint8_t i=PITCH; i<=YAW; i++) {
          gyroNoisePeak[i] = 0;
          gyroD[i] = 0;
          for (uint8_t j=0; j<GYRO_D_WINDOW_LENGTH; j++) {
                  gyroDWindow[i][j] = 0;
          }
  }
  // Setting offset values has an influence in the analog.c ISR
  // Therefore run measurement for 100ms to achive stable readings
  delay_ms_with_adc_measurement(100, 0);

  // gyroActivity = 0;
}

void analog_calibrate(void) {
#define OFFSET_CYCLES 64
  uint8_t i, axis;
  int32_t offsets[4] = { 0, 0, 0, 0};
  gyro_calibrate();
 
  // determine gyro bias by averaging (requires that the copter does not rotate around any axis!)
  for (i = 0; i < OFFSET_CYCLES; i++) {
    delay_ms_with_adc_measurement(10, 1);
    for (axis = PITCH; axis <= YAW; axis++) {
      offsets[axis] += rawGyroValue(axis);
    }
    offsets[3] += sensorInputs[AD_AIRPRESSURE];
  }
 
  for (axis = PITCH; axis <= YAW; axis++) {
    gyroOffset.offsets[axis] = (offsets[axis] + OFFSET_CYCLES / 2) / OFFSET_CYCLES;
    int16_t min = (512-200) * GYRO_OVERSAMPLING;
    int16_t max = (512+200) * GYRO_OVERSAMPLING;
    if(gyroOffset.offsets[axis] < min || gyroOffset.offsets[axis] > max)
      versionInfo.hardwareErrors[0] |= FC_ERROR0_GYRO_PITCH << axis;
  }

  airpressureOffset = (offsets[3] + OFFSET_CYCLES / 2) / OFFSET_CYCLES;
  int16_t min = 200;
  int16_t max = (1024-200) * 2;
  if(airpressureOffset < min || airpressureOffset > max)
    versionInfo.hardwareErrors[0] |= FC_ERROR0_PRESSURE;

  gyroOffset_writeToEEProm();

  startAnalogConversionCycle();
}