mouse_helpers.ino

/*

   Some helper functions we've written to simplify your code
   These were all taken from your previous labs!

   Functions that you might find useful:

    void hardwareSetup()            - sets up pins (modes, interrupts, etc)

    void applyPowerLeft()      - applies a power (-1 to 1) to the left wheel
    void applyPowerRight()     - applies a power (-1 to 1) to the right wheel
    void applyBrakeLeft()      - applies a braking force (0 to 1) to the left wheel
    void applyBrakeRight()     - applies a braking force (0 to 1) to the right wheel

    float getLinearVelocity()   - computes and returns our forward velocity (mm/sec)
    float getAngularVelocity()  - computes and returns our turning velocity (rad/sec)

    float getDistanceLeft()    - reads a distance from the left IR sensor (cm)
    float getDistanceRight()   - reads a distance from the right IR sensor (cm)
    float getDistanceCenter()  - reads a distance from the center IR sensor (cm)

*/

///////////////////////////////
// Helper for hardware setup //
///////////////////////////////

void hardwareSetup() {
  pinMode(PIN_LED1, OUTPUT);
  pinMode(PIN_LED2, OUTPUT);
  pinMode(PIN_BUTTON, INPUT);

  pinMode(PIN_MOTOR_LEFT_1, OUTPUT);
  pinMode(PIN_MOTOR_LEFT_2, OUTPUT);
  pinMode(PIN_MOTOR_RIGHT_1, OUTPUT);
  pinMode(PIN_MOTOR_RIGHT_2, OUTPUT);

  pinMode(PIN_ENCODER_LEFT_A, INPUT);
  pinMode(PIN_ENCODER_LEFT_B, INPUT);
  pinMode(PIN_ENCODER_RIGHT_A, INPUT);
  pinMode(PIN_ENCODER_RIGHT_B, INPUT);

  attachInterrupt(digitalPinToInterrupt(PIN_ENCODER_LEFT_B), leftEncoderRisingEdge, RISING);
  attachInterrupt(digitalPinToInterrupt(PIN_ENCODER_RIGHT_B), rightEncoderRisingEdge, RISING);

  Wire.begin();
  configureDistanceSensors();
}


////////////////////////////////////
// Motor driving helper functions //
////////////////////////////////////

// Apply power to a motor
// power = 0 means no power is applied
// power = 1 means 100% power forward
// power = -1 means 100% power backwards

void applyPowerLeft(float power) {
  if (INVERT_MOTOR_LEFT)
    power *= -1;

  if (power > 0) {
    analogWrite(PIN_MOTOR_LEFT_1, 255 - constrain(power * 255.0, 0, 255));
    digitalWrite(PIN_MOTOR_LEFT_2, HIGH);
  } else {
    digitalWrite(PIN_MOTOR_LEFT_1, HIGH);
    analogWrite(PIN_MOTOR_LEFT_2, 255 - constrain(power * -255.0, 0, 255));
  }
}

void applyPowerRight(float power) {
  if (INVERT_MOTOR_RIGHT)
    power *= -1;

  if (power > 0) {
    analogWrite(PIN_MOTOR_RIGHT_1, 255 - constrain(power * 255.0, 0, 255));
    digitalWrite(PIN_MOTOR_RIGHT_2, HIGH);
  } else {
    digitalWrite(PIN_MOTOR_RIGHT_1, HIGH);
    analogWrite(PIN_MOTOR_RIGHT_2, 255 - constrain(power * -255.0, 0, 255));
  }
}


// Apply a braking force to the motor
// power = 0 means no braking force
// power = 1 means 100% braking force

void applyBrakeLeft(float power) {
  analogWrite(PIN_MOTOR_LEFT_1, constrain(power * 255.0, 0, 255));
  analogWrite(PIN_MOTOR_LEFT_2, constrain(power * 255.0, 0, 255));
}

void applyBrakeRight(float power) {
  analogWrite(PIN_MOTOR_RIGHT_1, constrain(power * 255.0, 0, 255));
  analogWrite(PIN_MOTOR_RIGHT_2, constrain(power * 255.0, 0, 255));
}

//////////////////////////////
// Encoder helper functions //
//////////////////////////////

float velocity_left = 0; // millimeters/sec
float velocity_right = 0; // millimeters/sec

// Mouse physical parameters; these are used for velocity calculations
const float ENCODER_TICKS_PER_REVOLUTION = 420.0 / 2.0; // blaze it
const float WHEELBASE_DIAMETER = 95.0; // mm
const float WHEEL_DIAMETER = 34.0; // mm

// Precomputed constant used for calculating wheel velocities
// (VELOCITY_COEFF / encoder pulse width in microseconds) will give us the linear velocity of a wheel
const float VELOCITY_COEFF = WHEEL_DIAMETER * PI / ENCODER_TICKS_PER_REVOLUTION * 1000000.0;

// Encoder helper variables
unsigned long prev_pulse_time_right;
unsigned long prev_pulse_time_left;

// Encoder state variables
float getLinearVelocity() {
  return 0.5 * (velocity_left + velocity_right);
}

float getAngularVelocity() {
  return (velocity_right - velocity_left) / WHEELBASE_DIAMETER;
}

void checkEncodersZeroVelocity(void) {
  // Sets the wheel velocity to 0 if we haven't see an edge in a while
  unsigned long curr_time = micros();
  if (curr_time > prev_pulse_time_left + 100000) {
    velocity_left = 0;
  }
  if (curr_time > prev_pulse_time_right + 100000) {
    velocity_right = 0;
  }
}

void leftEncoderRisingEdge(void) {
  unsigned long curr_time = micros();

  int direction;
  if (digitalRead(PIN_ENCODER_LEFT_A) == !INVERT_ENCODER_LEFT) {
    direction = 1;
  } else {
    direction = -1;
  }

  if (direction * velocity_left < 0) {
    velocity_left = 0;
  } else {
    // Otherwise, convert the period of our pulse in mm/second
    velocity_left = direction * VELOCITY_COEFF / (curr_time - prev_pulse_time_left);
  }

  prev_pulse_time_left = curr_time;
}

void rightEncoderRisingEdge(void) {
  unsigned long curr_time = micros();

  int direction;
  if (digitalRead(PIN_ENCODER_RIGHT_A) == !INVERT_ENCODER_RIGHT) {
    direction = -1;
  } else {
    direction = 1;
  }

  if (direction * velocity_right < 0) {
    velocity_right = 0;
  } else {
    // Otherwise, convert the period of our pulse in mm/second
    velocity_right = direction * VELOCITY_COEFF / (curr_time - prev_pulse_time_right);
  }

  prev_pulse_time_right = curr_time;
}

////////////////////////////////
// ToF sensor helper functions //
////////////////////////////////

VL53L0X distance_sensor_center;
VL53L0X distance_sensor_left;
VL53L0X distance_sensor_right;

int left_reading;
int right_reading;
int center_reading;

float getDistanceLeft(void) {
  return left_reading / 10.0;
}

float getDistanceRight(void) {
  return right_reading / 10.0;
}

float getDistanceCenter(void) {
  return center_reading / 10.0;
}

long last_distance_reading;

void updateDistanceSensors(void) {
  // Read from the sensors at 10Hz
  if (millis() >= last_distance_reading + 100) {
    left_reading = distance_sensor_left.readRangeContinuousMillimeters();
    right_reading = distance_sensor_right.readRangeContinuousMillimeters();
    center_reading = distance_sensor_center.readRangeContinuousMillimeters();
    last_distance_reading = millis();
  }
}

void configureDistanceSensors(void) {


  // Set up the three distance sensors.
  //       This is be done as follows:
  //       1) Disable the left and right sensors.
  //       2) Set up the center sensor with an address of 0x01
  //       3) Enable the left sensor, and set it up with an address of 0x02
  //       4) Enable the right sensor, and set it up with an address of 0x03
  // IMPORTANT: do *not* write a HIGH signal to a reset pin; this will destroy the ToF sensor

  pinMode(PIN_TOF_LEFT_RESET, OUTPUT);
  digitalWrite(PIN_TOF_LEFT_RESET, LOW);
  pinMode(PIN_TOF_RIGHT_RESET, OUTPUT);
  digitalWrite(PIN_TOF_RIGHT_RESET, LOW);

  // Set up center sensor with address 0x01
  configureDistanceSensor(&distance_sensor_center, 0x01);

  // Set up left sensor with address 0x02
  pinMode(PIN_TOF_LEFT_RESET, INPUT);
  configureDistanceSensor(&distance_sensor_left, 0x02);

  // Set up right sensor with address 0x03
  pinMode(PIN_TOF_RIGHT_RESET, INPUT);
  configureDistanceSensor(&distance_sensor_right, 0x03);



}


void configureDistanceSensor(VL53L0X* sensor, uint8_t addr) {
  delay(100);
  sensor->setAddress(addr);
  sensor->init();
  //sensor->configureDefault();
  //sensor->writeReg(VL53L0X::SYSRANGE__MAX_CONVERGENCE_TIME, 30);
  //sensor->writeReg16Bit(VL53L0X::SYSALS__INTEGRATION_PERIOD, 50);
  sensor->setTimeout(500);
  //sensor->stopContinuous();
  sensor->startContinuous(100);
}