Gcode_executer.py

import RPi.GPIO as GPIO
import Motor_control
from Bipolar_Stepper_Motor_Class import Bipolar_Stepper_Motor
import time
from numpy import pi, sin, cos, arccos, arcsin
from math import sqrt

filename='yourfile.nc' #file name of the G code commands

GPIO.setmode(GPIO.BOARD)

MX=Bipolar_Stepper_Motor(13,18,1234,170) #takes step pin,dir pin,limit pin,backlash (optional)

MY=Bipolar_Stepper_Motor(7,11,1234,670) # the limit switches are currently unimplemented

Laser_switch=15

dx=0.00078 #resolution in x direction. Unit: mm
dy=0.00078 #resolution in y direction. Unit: mm

Engraving_speed=1 #unit=mm/sec=0.04in/sec

GPIO.setup(Laser_switch,GPIO.OUT)

GPIO.output(Laser_switch,0)

speed=Engraving_speed/min(dx,dy)      #step/sec

def XYposition(lines):
    #given a movement command line, return the X Y position
    xchar_loc=lines.index('X')
    i=xchar_loc+1
    while (47<ord(lines[i])<58)|(lines[i]=='.')|(lines[i]=='-'):
        i+=1
    x_pos=float(lines[xchar_loc+1:i])

    ychar_loc=lines.index('Y')
    i=ychar_loc+1
    while (47<ord(lines[i])<58)|(lines[i]=='.')|(lines[i]=='-'):
        i+=1
    y_pos=float(lines[ychar_loc+1:i])

    return x_pos,y_pos

def IJposition(lines):
    #given a G02 or G03 movement command line, return the I J position
    ichar_loc=lines.index('I')
    i=ichar_loc+1
    while (47<ord(lines[i])<58)|(lines[i]=='.')|(lines[i]=='-'):
        i+=1
    i_pos=float(lines[ichar_loc+1:i])

    jchar_loc=lines.index('J')
    i=jchar_loc+1
    while (47<ord(lines[i])<58)|(lines[i]=='.')|(lines[i]=='-'):
        i+=1
    j_pos=float(lines[jchar_loc+1:i])

    return i_pos,j_pos

def moveto(MX,x_pos,dx,MY,y_pos,dy,speed,engraving):
#Move to (x_pos,y_pos) (in real unit)
    stepx=int(round(x_pos/dx))-MX.position
    stepy=int(round(y_pos/dy))-MY.position

    Total_step=sqrt((stepx**2+stepy**2))

    if Total_step>0:
        if lines[0:3]=='G0 ': #fast movement
            print 'No Laser, fast movement: Dx=', stepx, '  Dy=', stepy
            Motor_control.Motor_Step(MX,stepx,MY,stepy,3000)
        else:
##            print 'Laser on, movement: Dx=', stepx, '  Dy=', stepy
            Motor_control.Motor_Step(MX,stepx,MY,stepy,speed)
    return 0

try:#read and execute G code
    for lines in open(filename,'r'):
        if lines==[]:
            1 #blank lines
        elif lines[0:3]=='G90':
            print 'start'

        elif lines[0:3]=='G20':# working in inch;
            dx/=25.4
            dy/=25.4
            print 'Working in inch';

        elif lines[0:3]=='G21':# working in mm;
            print 'Working in mm'

        elif lines[0:3]=='M05':
            GPIO.output(Laser_switch,0)
            print 'Laser turned off'

        elif lines[0:3]=='M03':
            GPIO.output(Laser_switch,1)
            print 'Laser turned on'

        elif lines[0:3]=='M02':
            GPIO.output(Laser_switch,0)
            print 'Finished! Shutting down...'
            break
        elif (lines[0:3]=='G1F')|(lines[0:4]=='G1 F'):
            1#do nothing
        elif (lines[0:3]=='G0 ')|(lines[0:3]=='G1 ')|(lines[0:3]=='G01'):#|(lines[0:3]=='G02')|(lines[0:3]=='G03'):
            #linear engraving movement
            if (lines[0:3]=='G0 '):
                engraving=False
            else:
                engraving=True

            [x_pos,y_pos]=XYposition(lines)
            moveto(MX,x_pos,dx,MY,y_pos,dy,speed,engraving)

        elif (lines[0:3]=='G02')|(lines[0:3]=='G03'): #circular interpolation
            old_x_pos=x_pos
            old_y_pos=y_pos

            [x_pos,y_pos]=XYposition(lines)
            [i_pos,j_pos]=IJposition(lines)

            xcenter=old_x_pos+i_pos   #center of the circle for interpolation
            ycenter=old_y_pos+j_pos


            Dx=x_pos-xcenter
            Dy=y_pos-ycenter      #vector [Dx,Dy] points from the circle center to the new position

            r=sqrt(i_pos**2+j_pos**2)   # radius of the circle

            e1=[-i_pos,-j_pos] #pointing from center to current position
            if (lines[0:3]=='G02'): #clockwise
                e2=[e1[1],-e1[0]]     #perpendicular to e1. e2 and e1 forms x-y system (clockwise)
            else:                   #counterclockwise
                e2=[-e1[1],e1[0]]      #perpendicular to e1. e1 and e2 forms x-y system (counterclockwise)

            #[Dx,Dy]=e1*cos(theta)+e2*sin(theta), theta is the open angle

            costheta=(Dx*e1[0]+Dy*e1[1])/r**2;
            sintheta=(Dx*e2[0]+Dy*e2[1])/r**2;        #theta is the angule spanned by the circular interpolation curve

            if costheta>1:  # there will always be some numerical errors! Make sure abs(costheta)<=1
        costheta=1;
        elif costheta<-1:
        costheta=-1;

            theta=arccos(costheta);
            if sintheta<0:
                theta=2.0*pi-theta;

            no_step=int(round(r*theta/dx/5.0));   # number of point for the circular interpolation

            for i in range(1,no_step+1):
                tmp_theta=i*theta/no_step;
                tmp_x_pos=xcenter+e1[0]*cos(tmp_theta)+e2[0]*sin(tmp_theta);
                tmp_y_pos=ycenter+e1[1]*cos(tmp_theta)+e2[1]*sin(tmp_theta);
                moveto(MX,tmp_x_pos,dx,MY, tmp_y_pos,dy,speed,True);

except KeyboardInterrupt:
    pass

GPIO.output(Laser_switch,0);   # turn off laser
moveto(MX,0,dx,MY,0,dy,3000,False);  # move back to Origin

GPIO.cleanup();