Saturday, 3 September 2011

Arduino Servo Points Controller Software

First, a Disclaimer
  • I freely admit that this code is not exactly pretty. However, it does work and is sufficiently bug free.
  • It needs comments and should be refactored to use a class for the Points struct.
  • It's not been code reviewed and I'd be happy for your gracious comments.
Overview

There are only 2 files - Points.h and the main Arduino sketch. I was going to work it all into one file but there are some (known) bugs in the Arduino IDE that forced me to move some of my typedefs into the header file. The bug in the IDE si to do with the fact that the main sketch file is not parsed in strict line number order (somehow!).

The basic concept for this software is that I have an array of Points each of which is controlled by a well defined state machine. The system is essentially a table driven finite state machine with the context of where each point is "up to" stored in the Point data structure.

Feel free to pinch this code.

Points.h

#ifndef    POINTS_H
#define    POINTS_H    1

/*
 * Points.h - my arduino driven switch machine software….
 */

typedef enum  { cal_st, cal_sw, moving_sw, moving_st, 

                idle_sw, idle_st
} PointState ;

typedef enum  { cal_enter, cal_exit, mov_straight, 

                mov_switch, set_pt_changed, pt_tick 
} PointEvent ;



typedef struct  {
  int  ID;
  int  servo_pin;
  int  calib_pin;
  int  control_pin;
  int  set_pt_pin;
  int  eeprom_sw_addr;
  int  eeprom_st_addr;
 
  int  straight_angle;
  int  switch_angle;
 
  int  calib;
  int  control;
  int  set_point;

  int  current_angle;
  int  dest_angle;
 
  PointState  current_state;
 
  Servo point_servo;

} Point;

typedef    struct    {
    PointState    current;
    PointEvent    event;
    PointState    next;
    void          (*transition)( Point* p);
} PointStateElement;


#endif    POINTS_H

And the main Arduino Sketch

#include <Servo.h>
#include <EEPROM.h>
#include "<insert path>/Points.h"

#define  NUM_POINTS          4

#define  SVO_START_PIN       10  // The first pin to which a servo is connected
#define  CTL_START_PIN       6   // The first pin to be used for controlling the points
#define  CAL_START_PIN       2   // The first pin to be used for controlling calibration
#define  SET_PT_PIN          0   // The analogue pin to be used for reading the set point
#define  PT_EEPROM_ST        0   // The first address in the EEPROM for point settings to be kept

//#define  SER_OUT             1   // If defined, serial debug output is compiled in

#define  SERVO_DFT_ANG       90  // Where the servo will sit if it is uncalibrated
#define  SERVO_MIN_ANG       70
#define  SERVO_MAX_ANG       110

#define  IsAngleValid(a)     (((a) >= SERVO_MIN_ANG) && ((a) <= SERVO_MAX_ANG))

#define  PT_POS_STRAIGHT     1
#define  PT_POS_SWITCH       0
#define  PT_CALIBRATE        0
#define  PT_OPERATE          1

void
Points_error(Point* p)
{
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" error.");
#endif
}

void
Points_nop(Point* p)
{

}

void
Points_write_cal_st(Point* p)
{
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" writing calibration for straight.");
#endif
  EEPROM.write(p->eeprom_st_addr , p->current_angle);
  p->straight_angle = p->current_angle;
}

void
Points_match_set_pt(Point* p)
{
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" match set point.");
#endif
  p->current_angle = p->set_point;
  p->point_servo.write(p->set_point);
}

void
Points_write_cal_sw(Point* p)
{
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" writing calibration for switch.");
#endif
  EEPROM.write(p->eeprom_sw_addr , p->current_angle);
  p->switch_angle = p->current_angle;

}

void
Points_start_moving_st(Point* p)
{
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println("start moving straight.");
#endif
  if ( IsAngleValid(p->straight_angle) )
  {
    p->dest_angle = p->straight_angle;
  }
  else
  {
    p->point_servo.write(SERVO_DFT_ANG - 2);
    p->point_servo.write(SERVO_DFT_ANG + 2);
    p->point_servo.write(SERVO_DFT_ANG);
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" straight is uncalibrated");
#endif 
  }
 
}

void
Points_start_moving_sw(Point* p)
{
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" start moving switch.");
#endif
  if ( IsAngleValid(p->switch_angle) )
  {
    p->dest_angle = p->switch_angle;
  }
  else
  {
    p->point_servo.write(SERVO_DFT_ANG - 2);
    p->point_servo.write(SERVO_DFT_ANG + 2);
    p->point_servo.write(SERVO_DFT_ANG);
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" switch is uncalibrated");
#endif
  }
}

void
Points_move_step(Point* p)
{
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println(" move_step.");
#endif
   
    if(p->current_angle < p->dest_angle)
    {
      p->current_angle ++;
    }
    else if(p->current_angle > p->dest_angle)
    {
      p->current_angle --;
    }
   
    p->point_servo.write(p->current_angle);
    if(p->current_angle == p->dest_angle)
    {
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.print(" reached destination ");
  Serial.print(p->dest_angle);
  Serial.print("( ");
  Serial.print(p->switch_angle);
  Serial.print(", ");
  Serial.print(p->straight_angle);
  Serial.println(")");
#endif

      if(p->dest_angle == p->switch_angle)
        p->current_state = idle_sw;
      else
        p->current_state = idle_st;
    }
}


PointStateElement PointStateTable[] = {
  {cal_st,    cal_enter,      cal_st,     Points_error        },
  {cal_st,    cal_exit,       idle_st,    Points_write_cal_st },
  {cal_st,    mov_straight,   cal_st,     Points_error        },
  {cal_st,    mov_switch,     cal_sw,     Points_nop          },
  {cal_st,    set_pt_changed, cal_st,     Points_match_set_pt },
  {cal_st,    pt_tick,        cal_st,     Points_nop          },
  {cal_sw,    cal_enter,      cal_sw,     Points_error        },
  {cal_sw,    cal_exit,       idle_sw,    Points_write_cal_sw },
  {cal_sw,    mov_straight,   cal_st,     Points_nop          },
  {cal_sw,    mov_switch,     cal_sw,     Points_error        },
  {cal_sw,    set_pt_changed, cal_sw,     Points_match_set_pt },
  {cal_sw,    pt_tick,        cal_sw,     Points_nop          },
  {moving_sw, cal_enter,      cal_sw,     Points_match_set_pt },
  {moving_sw, cal_exit,       moving_sw,  Points_error        },
  {moving_sw, mov_straight,   moving_st,  Points_start_moving_st},
  {moving_sw, mov_switch,     moving_sw,  Points_error        },
  {moving_sw, set_pt_changed, moving_sw,  Points_nop          },
  {moving_sw, pt_tick,        moving_sw,  Points_move_step    },
  {moving_st, cal_enter,      cal_st,     Points_match_set_pt },
  {moving_st, cal_exit,       moving_st,  Points_error        },
  {moving_st, mov_straight,   moving_st,  Points_error        },
  {moving_st, mov_switch,     moving_sw,  Points_start_moving_sw},
  {moving_st, set_pt_changed, moving_st,  Points_nop          },
  {moving_st, pt_tick,        moving_st,  Points_move_step    },
  {idle_sw,   cal_enter,      cal_sw,     Points_match_set_pt },
  {idle_sw,   cal_exit,       idle_sw,    Points_error        },
  {idle_sw,   mov_straight,   moving_st,  Points_start_moving_st},
  {idle_sw,   mov_switch,     idle_sw,    Points_error        },
  {idle_sw,   set_pt_changed, idle_sw,    Points_nop          },
  {idle_sw,   pt_tick,        idle_sw,    Points_nop          },
  {idle_st,   cal_enter,      cal_st,     Points_match_set_pt },
  {idle_st,   cal_exit,       idle_st,    Points_error        },
  {idle_st,   mov_straight,   idle_st,    Points_error        },
  {idle_st,   mov_switch,     moving_sw,  Points_start_moving_sw},
  {idle_st,   set_pt_changed, idle_st,    Points_nop          },
  {idle_st,   pt_tick,        idle_st,    Points_nop          }
};

#define  NUM_STATES  (sizeof(PointStateTable)/sizeof(PointStateElement))

int
PointInit(  Point* p, int ID,  int  ser_pin, int  cal_pin, int  con_pin, int  eeprom_addr, int set_pt_pin )
{
  int  val;
 
  p->ID = ID;
  p->servo_pin = ser_pin;
  p->calib_pin = cal_pin;
  p->control_pin = con_pin;
  p->eeprom_sw_addr = eeprom_addr;
  p->eeprom_st_addr = eeprom_addr + 1;
  p->set_pt_pin = set_pt_pin;
 
  p->point_servo.attach(ser_pin);
 
  p->straight_angle = EEPROM.read(p->eeprom_st_addr);
  p->switch_angle = EEPROM.read(p->eeprom_sw_addr);
 
  pinMode(p->calib_pin, INPUT);
  pinMode(p->control_pin, INPUT);
 
  val = analogRead(p->set_pt_pin);
  p->calib = PT_OPERATE;
  p->control = PT_POS_STRAIGHT;
  p->set_point = map(val, 0, 1023, SERVO_MIN_ANG, SERVO_MAX_ANG);
 
  p->current_state = moving_st;
  p->point_servo.write(SERVO_DFT_ANG);
 
  p->current_angle = SERVO_DFT_ANG;
  p->dest_angle = SERVO_DFT_ANG;
 
}


PointEvent
PointGetEvent(  Point* p)
{
  int  setval;
  int  set_pt;
 
  if(( p->calib == PT_CALIBRATE) && (digitalRead(p->calib_pin) == PT_OPERATE))
  {
    p->calib = PT_OPERATE;
    delay(20);        //debounce it
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println("cal_exit");
#endif
    return(cal_exit);
  }
  else if(( p->calib == PT_OPERATE) && (digitalRead(p->calib_pin) == PT_CALIBRATE))
  {
    p->calib = PT_CALIBRATE;
    delay(20);        //debounce it
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println("cal_enter");
#endif
    return(cal_enter);
  }
  if(( p->control == PT_POS_STRAIGHT) && (digitalRead(p->control_pin) == PT_POS_SWITCH))
  {
    p->control = PT_POS_SWITCH;
    delay(20);       //debounce it
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println("mov_switch");
#endif
    return(mov_switch);
  }
  else if(( p->control == PT_POS_SWITCH) && (digitalRead(p->control_pin) == PT_POS_STRAIGHT))
  {
    p->control = PT_POS_STRAIGHT;
    delay(20);       //debounce it
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.println("mov_straight");
#endif
    return(mov_straight);
  }
 
  setval = analogRead(p->set_pt_pin);
  set_pt = map(setval, 0, 1023, SERVO_MIN_ANG, SERVO_MAX_ANG);
  if( p->set_point != set_pt)
  {
    p->set_point = set_pt;
    delay(20);
#ifdef  SER_OUT
  Serial.print(p->ID);
  Serial.print("set_pt_changed: ");
  Serial.println(set_pt);
#endif
    return(set_pt_changed);
  }
 
  delay(20);
  return ( pt_tick );
}

void
PointHandleEvent(  Point* p, PointEvent e)
{
    int         i,j;
    PointState  cs;
   
    cs = p->current_state;
    i = 0;
    while( i < NUM_STATES)
    {
      if ((PointStateTable[i].current == cs) && (PointStateTable[i].event == e))
      {
        p->current_state = PointStateTable[i].next;
        (*PointStateTable[i].transition)(p);
        i = NUM_STATES;     
      }
      else
        i++;
    } 
 
}

void
PointRun( Point* p)
{
  PointEvent  e;
 
  e = PointGetEvent(p);
  PointHandleEvent(p,e);
}

Point  PointArray[NUM_POINTS];


void setup()
{
  int  i;

#ifdef  SER_OUT
  Serial.begin(9600);
#endif
 
  for ( i = 0; i < NUM_POINTS; i++)
  {
    PointInit(&PointArray[i], i, SVO_START_PIN + i, CAL_START_PIN + i, CTL_START_PIN + i, PT_EEPROM_ST + i*2, SET_PT_PIN);
  }
 
}

void loop()
{
  int  i;
 
  for ( i = 0; i < NUM_POINTS; i++)
  {
    PointRun(&PointArray[i]);
  }
 
}

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