Subversion Repositories FlightCtrl

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#include <avr/io.h>

#include <avr/interrupt.h>

#include <avr/pgmspace.h>

#include "analog.h"

#include "sensors.h"

// for Delay functions

#include "timer0.h"

// For DebugOut

#include "uart0.h"

// For reading and writing acc. meter offsets.

#include "eeprom.h"

/*

 * 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 int16_t rawGyroSum[3];

volatile int16_t acc[3];

volatile int16_t filteredAcc[2]={0,0};

/*

 * 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.

 */

volatile int16_t gyro_PID[2];

volatile int16_t gyro_ATT[2];

volatile int16_t gyroD[2];

volatile int16_t yawGyro;

/*

 * 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.

 */

volatile int16_t gyroOffset[3] = {

        512 * GYRO_SUMMATION_FACTOR_PITCHROLL,

        512 * GYRO_SUMMATION_FACTOR_PITCHROLL,

        512 * GYRO_SUMMATION_FACTOR_YAW

};

volatile int16_t accOffset[3] = {

        512 * ACC_SUMMATION_FACTOR_PITCHROLL,

        512 * ACC_SUMMATION_FACTOR_PITCHROLL,

        512 * ACC_SUMMATION_FACTOR_Z

};

/*

 * This allows some experimentation with the gyro filters.

 * Should be replaced by #define's later on...

 */

volatile uint8_t GYROS_PID_FILTER;

volatile uint8_t GYROS_ATT_FILTER;

volatile uint8_t GYROS_D_FILTER;

volatile uint8_t ACC_FILTER;

/*

 * Air pressure

 */

volatile uint8_t rangewidth = 106;

// Direct from sensor, irrespective of range.

// volatile uint16_t rawAirPressure;

// Value of 2 samples, with range.

volatile uint16_t simpleAirPressure;

// Value of AIRPRESSURE_SUMMATION_FACTOR samples, with range, filtered.

volatile int32_t filteredAirPressure;

// Partial sum of AIRPRESSURE_SUMMATION_FACTOR samples.

volatile int32_t airPressureSum;

// The number of samples summed into airPressureSum so far.

volatile uint8_t pressureMeasurementCount;

/*

 * 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.

 */

volatile int16_t UBat = 100;

/*

 * Control and status.

 */

volatile uint16_t ADCycleCount = 0;

volatile uint8_t analogDataReady = 1;

/*

 * Experiment: Measuring vibration-induced sensor noise.

 */

volatile uint16_t gyroNoisePeak[2];

volatile uint16_t accNoisePeak[2];

// 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_ACC_PITCH,

  AD_ACC_ROLL,

  AD_AIRPRESSURE,

  AD_GYRO_PITCH,

  AD_GYRO_ROLL,

  AD_ACC_Z,       // at 8, measure Z acc.

  AD_GYRO_PITCH,

  AD_GYRO_ROLL,

  AD_GYRO_YAW,    // at 11, finish yaw gyro

  AD_ACC_PITCH,   // at 12, finish pitch axis acc.

  AD_ACC_ROLL,    // at 13, finish roll axis acc.

  AD_AIRPRESSURE, // at 14, finish air pressure.

  AD_GYRO_PITCH,  // at 15, finish pitch gyro

  AD_GYRO_ROLL,   // at 16, finish roll gyro

  AD_UBAT         // at 17, measure battery.

};

// 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) | AD_GYRO_PITCH;

  //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 = (0<<ADEN)|(0<<ADSC)|(0<<ADATE)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0)|(0<<ADIE);

  //Set ADC Control and Status Register B

  //Trigger Source to Free Running Mode

  ADCSRB &= ~((1 << ADTS2)|(1 << ADTS1)|(1 << ADTS0));

  // Start AD conversion

  analog_start();

  // restore global interrupt flags

  SREG = sreg;

}

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;

  }

}

uint16_t getSimplePressure(int advalue) {

  return (uint16_t)OCR0A * (uint16_t)rangewidth + advalue;

}

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

 * Interrupt Service Routine for ADC            

 * Runs at 312.5 kHz or 3.2 µs. When all states are

 * processed the interrupt is disabled and further

 * AD conversions are stopped.

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

ISR(ADC_vect) {

  static uint8_t ad_channel = AD_GYRO_PITCH, state = 0;

  static uint16_t sensorInputs[8] = {0,0,0,0,0,0,0,0};

  static uint16_t pressureAutorangingWait = 25;

  uint16_t rawAirPressure;

  uint8_t i, axis;

  int16_t newrange;

  // for various filters...

  int16_t tempOffsetGyro, tempGyro;

  sensorInputs[ad_channel] += ADC;

  /*

   * Actually we don't need this "switch". We could do all the sampling into the

   * sensorInputs array first, and all the processing after the last sample.

   */

  switch(state++) {

  case 8: // Z acc      

  if (ACC_REVERSED[Z])

    acc[Z] = accOffset[Z] - sensorInputs[AD_ACC_Z];

  else

    acc[Z] = sensorInputs[AD_ACC_Z] - accOffset[Z];

  break;

  case 11: // yaw gyro

    rawGyroSum[YAW] = sensorInputs[AD_GYRO_YAW];

    if (GYRO_REVERSED[YAW])

      yawGyro = gyroOffset[YAW] - sensorInputs[AD_GYRO_YAW];

    else

      yawGyro = sensorInputs[AD_GYRO_YAW] - gyroOffset[YAW];

    break;

  case 12: // pitch axis acc.

    if (ACC_REVERSED[PITCH])

      acc[PITCH] = accOffset[PITCH] - sensorInputs[AD_ACC_PITCH];

    else

      acc[PITCH] = sensorInputs[AD_ACC_PITCH] - accOffset[PITCH];

    filteredAcc[PITCH] = (filteredAcc[PITCH] * (ACC_FILTER-1) + acc[PITCH]) / ACC_FILTER;

    measureNoise(acc[PITCH], &accNoisePeak[PITCH], 1);

    break;

  case 13: // roll axis acc.

    if (ACC_REVERSED[ROLL])

      acc[ROLL] = accOffset[ROLL] - sensorInputs[AD_ACC_ROLL];

    else

      acc[ROLL] = sensorInputs[AD_ACC_ROLL] - accOffset[ROLL];

    filteredAcc[ROLL] = (filteredAcc[ROLL] * (ACC_FILTER-1) + acc[ROLL]) / ACC_FILTER;

    measureNoise(acc[ROLL], &accNoisePeak[ROLL], 1);

    break;

  case 14: // air pressure

    if (pressureAutorangingWait) {

      //A range switch was done recently. Wait for steadying.

      pressureAutorangingWait--;

      break;

    }

    rawAirPressure = sensorInputs[AD_AIRPRESSURE];

    if (rawAirPressure < MIN_RAWPRESSURE) {

      // value is too low, so decrease voltage on the op amp minus input, making the value higher.

      newrange = OCR0A - (MAX_RAWPRESSURE - rawAirPressure) / rangewidth - 1;

      if (newrange > MIN_RANGES_EXTRAPOLATION) {

        pressureAutorangingWait = (OCR0A - newrange) * AUTORANGE_WAIT_FACTOR;

        OCR0A = newrange;

      } else {

        if (OCR0A) {

          OCR0A--;

          pressureAutorangingWait = AUTORANGE_WAIT_FACTOR;

        }

      }

    } else if (rawAirPressure > MAX_RAWPRESSURE) {

      // value is too high, so increase voltage on the op amp minus input, making the value lower.

      // If near the end, make a limited increase

      newrange = OCR0A + (rawAirPressure - MIN_RAWPRESSURE) / rangewidth - 1;

      if (newrange < MAX_RANGES_EXTRAPOLATION) {

      pressureAutorangingWait = (newrange - OCR0A) * AUTORANGE_WAIT_FACTOR;

      OCR0A = newrange;

      } else {

        if (OCR0A<254) {

          OCR0A++;

          pressureAutorangingWait = AUTORANGE_WAIT_FACTOR;

        }

      }

    }

    // Even if the sample is off-range, use it.

    simpleAirPressure = getSimplePressure(rawAirPressure);

    if (simpleAirPressure < MIN_RANGES_EXTRAPOLATION * rangewidth) {

      // Danger: pressure near lower end of range. If the measurement saturates, the 

      // copter may climb uncontrolled... Simulate a drastic reduction in pressure.

      airPressureSum += (int16_t)MIN_RANGES_EXTRAPOLATION * rangewidth + (simpleAirPressure - (int32_t)MIN_RANGES_EXTRAPOLATION * rangewidth) * PRESSURE_EXTRAPOLATION_COEFF;

    } else if (simpleAirPressure > MAX_RANGES_EXTRAPOLATION * rangewidth) {

      // Danger: pressure near upper end of range. If the measurement saturates, the 

      // copter may fall uncontrolled... Simulate a drastic increase in pressure.

      airPressureSum += (int16_t)MAX_RANGES_EXTRAPOLATION * rangewidth + (simpleAirPressure - (int32_t)MAX_RANGES_EXTRAPOLATION * rangewidth) * PRESSURE_EXTRAPOLATION_COEFF;

    } else {

      // normal case.

      airPressureSum += simpleAirPressure;

    }

    // 2 samples were added.

    pressureMeasurementCount += 2;

    if (pressureMeasurementCount == AIRPRESSURE_SUMMATION_FACTOR) {

      filteredAirPressure = (filteredAirPressure * (AIRPRESSURE_FILTER-1) + airPressureSum + AIRPRESSURE_FILTER/2) / AIRPRESSURE_FILTER;

      pressureMeasurementCount = airPressureSum = 0;

    }

    // DebugOut.Analog[14] = OCR0A;

    // DebugOut.Analog[15] = simpleAirPressure;

    DebugOut.Analog[11] = UBat;

    DebugOut.Analog[27] = acc[Z];

    break;

  case 15:

  case 16: // pitch or roll gyro.

    axis = state - 16;

    tempGyro = rawGyroSum[axis] = sensorInputs[AD_GYRO_PITCH - axis];

        // DebugOut.Analog[6 + 3 * axis ] = tempGyro;

    /*

     * 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.GlobalConfig & CFG_ROTARY_RATE_LIMITER) {

      if (tempGyro < SENSOR_MIN_PITCHROLL) {

        tempGyro = tempGyro * EXTRAPOLATION_SLOPE - EXTRAPOLATION_LIMIT;

      }

      else if (tempGyro > SENSOR_MAX_PITCHROLL) {

        tempGyro = (tempGyro - SENSOR_MAX_PITCHROLL) * EXTRAPOLATION_SLOPE + SENSOR_MAX_PITCHROLL;

      }

    }

    // 2) Apply sign and offset, scale before filtering.

    if (GYRO_REVERSED[axis]) {

      tempOffsetGyro = (gyroOffset[axis] - tempGyro) * GYRO_FACTOR_PITCHROLL;

    } else {

      tempOffsetGyro = (tempGyro - gyroOffset[axis]) * GYRO_FACTOR_PITCHROLL;

    }

    // 3) Scale and filter.

    tempOffsetGyro = (gyro_PID[axis] * (GYROS_PID_FILTER-1) + tempOffsetGyro) / GYROS_PID_FILTER;

    // 4) Measure noise.

    measureNoise(tempOffsetGyro, &gyroNoisePeak[axis], GYRO_NOISE_MEASUREMENT_DAMPING);

    // 5) Differential measurement. 

    gyroD[axis] = (gyroD[axis] * (GYROS_D_FILTER-1) + (tempOffsetGyro - gyro_PID[axis])) / GYROS_D_FILTER;

    // 6) Done.

    gyro_PID[axis] = tempOffsetGyro;

    /*

     * Now process the data for attitude angles.

     */

    tempGyro = rawGyroSum[axis];

    // 1) Apply sign and offset, scale before filtering.

    if (GYRO_REVERSED[axis]) {

      tempOffsetGyro = (gyroOffset[axis] - tempGyro) * GYRO_FACTOR_PITCHROLL;

    } else {

      tempOffsetGyro = (tempGyro - gyroOffset[axis]) * GYRO_FACTOR_PITCHROLL;

    }

    // 2) Filter.

    gyro_ATT[axis] = (gyro_ATT[axis] * (GYROS_ATT_FILTER-1) + tempOffsetGyro) / GYROS_ATT_FILTER;

    break;

  case 17:

    // 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;

    analogDataReady = 1; // mark

    ADCycleCount++;

    // Stop the sampling. Cycle is over.

    state = 0;

    for (i=0; i<8; i++) {

      sensorInputs[i] = 0;

    }

    break;

  default: {} // do nothing.

  }

  // set up for next state.

  ad_channel = pgm_read_byte(&channelsForStates[state]);

  // ad_channel = channelsForStates[state];

  // set adc muxer to next ad_channel

  ADMUX = (ADMUX & 0xE0) | ad_channel;

  // after full cycle stop further interrupts

  if(state) analog_start();

}

void analog_calibrate(void) {

#define GYRO_OFFSET_CYCLES 32

  uint8_t i, axis;

  int32_t deltaOffsets[3] = {0,0,0};

  // Set the filters... to be removed again, once some good settings are found.

  GYROS_PID_FILTER = (dynamicParams.UserParams[4]   & 0b00000011)       + 1;

  GYROS_ATT_FILTER = ((dynamicParams.UserParams[4]  & 0b00001100) >> 2) + 1;

  GYROS_D_FILTER = ((dynamicParams.UserParams[4]    & 0b00110000) >> 4) + 1;

  ACC_FILTER = ((dynamicParams.UserParams[4]        & 0b11000000) >> 6) + 1;

  gyro_calibrate();

  // determine gyro bias by averaging (requires that the copter does not rotate around any axis!)

  for(i=0; i < GYRO_OFFSET_CYCLES; i++) {

    Delay_ms_Mess(20);

    for (axis=PITCH; axis<=YAW; axis++) {

      deltaOffsets[axis] += rawGyroSum[axis];

    }

  }

  for (axis=PITCH; axis<=YAW; axis++) {

    gyroOffset[axis] =  (deltaOffsets[axis] + GYRO_OFFSET_CYCLES/2) / GYRO_OFFSET_CYCLES;

    DebugOut.Analog[20+axis] = gyroOffset[axis];

  }

  // Noise is relative to offset. So, reset noise measurements when changing offsets.

  gyroNoisePeak[PITCH] = gyroNoisePeak[ROLL] = 0;

  accOffset[PITCH] = GetParamWord(PID_ACC_PITCH);

  accOffset[ROLL]  = GetParamWord(PID_ACC_ROLL);

  accOffset[Z]     = GetParamWord(PID_ACC_Z);

  // Rough estimate. Hmm no nothing happens at calibration anyway.

  // airPressureSum = simpleAirPressure * (AIRPRESSURE_SUMMATION_FACTOR/2);

  // pressureMeasurementCount = 0;

  // Experiment!

  // filteredAirPressureOffset = filteredAirPressure - 1000L;

  Delay_ms_Mess(100);

}

/*

 * Find acc. offsets for a neutral reading, and write them to EEPROM.

 * Does not (!} update the local variables. This must be done with a

 * call to analog_calibrate() - this always (?) is done by the caller

 * anyway. There would be nothing wrong with updating the variables

 * directly from here, though.

 */

void analog_calibrateAcc(void) {

#define ACC_OFFSET_CYCLES 10

  uint8_t i, axis;

  int32_t deltaOffset[3] = {0,0,0};

  int16_t filteredDelta;

  // int16_t pressureDiff, savedRawAirPressure;

  for(i=0; i < ACC_OFFSET_CYCLES; i++) {

    Delay_ms_Mess(10);

    for (axis=PITCH; axis<=YAW; axis++) {

      deltaOffset[axis] += acc[axis];

    }

  }

  for (axis=PITCH; axis<=YAW; axis++) {

    filteredDelta = (deltaOffset[axis] + ACC_OFFSET_CYCLES / 2) / ACC_OFFSET_CYCLES;

    accOffset[axis] += ACC_REVERSED[axis] ? -filteredDelta : filteredDelta;

  }

  // Save ACC neutral settings to eeprom

  SetParamWord(PID_ACC_PITCH, accOffset[PITCH]);

  SetParamWord(PID_ACC_ROLL,  accOffset[ROLL]);

  SetParamWord(PID_ACC_Z,     accOffset[Z]);

  // Noise is relative to offset. So, reset noise measurements when

  // changing offsets.

  accNoisePeak[PITCH] = accNoisePeak[ROLL] = 0;

  // Setting offset values has an influence in the analog.c ISR

  // Therefore run measurement for 100ms to achive stable readings

  Delay_ms_Mess(100);

  // Set the feedback so that air pressure ends up in the middle of the range.

  // (raw pressure high --> OCR0A also high...)

  // OCR0A += (rawAirPressure - 512) / rangewidth;

  // Delay_ms_Mess(500);

  /*

    pressureDiff = 0;

    // DebugOut.Analog[16] = rawAirPressure;

    #define PRESSURE_CAL_CYCLE_COUNT 2

    for (i=0; i<PRESSURE_CAL_CYCLE_COUNT; i++) {

    savedRawAirPressure = rawAirPressure;

    OCR0A++;

    Delay_ms_Mess(200);

    // raw pressure will decrease.

    pressureDiff += (savedRawAirPressure - rawAirPressure);

    savedRawAirPressure = rawAirPressure;

    OCR0A--;

    Delay_ms_Mess(200);

    // raw pressure will increase.

    pressureDiff += (rawAirPressure - savedRawAirPressure);

    }

    // DebugOut.Analog[16] =

    rangewidth = (pressureDiff + PRESSURE_CAL_CYCLE_COUNT * 2 - 1) / (PRESSURE_CAL_CYCLE_COUNT * 2);

  */

}