This machine consists of 2 servos controlling an aluminum arm with a pen attached. It is an attempted improvement on DM#1 by moving the weight back to the shoulder The belt used on this machine was completely unusable because it slipped and then all coordinates were useless. This caused the machine to leave the boundries and destroy itself. DM3 is a rebuild of this arm with a plastic chain and sprocket arrangement.

This machine consists of 2 servos controlling an aluminum arm with a pen attached.
I origionally developed this hardware using a DS5000 on a simsick.

Code

 /*--------------------------------------------------------------------servo.c
 *  Test program for drawing machines.
 *
 *  This code is targeted at an 89S4051 and compiles with sdcc.
 *
 *  Author: Donald Delmar Davis,
 *  w/ Suggestions from to Bernard Winter and Dan Micheals
 *
 *  Date: 28apr02
 *
 *  Status: alfa VERY alfa.
 *
 *  Notes: This seems to work farely well.
 */

 #include 
 #define NSERVOS 3
 #define SERVO0	P1.7
 #define SERVO1	P1.6
 #define SERVO2	P1.5
 #define KFREQ   11059
 #define STRIM	- 693
 #define ETRIM	+ 81

 unsigned int DegreesX92delay(unsigned int DegreesX9);
 unsigned char CurrentServo;
 unsigned int SpaceDelay;
 unsigned int Servo0Delay;
 unsigned int Servo1Delay;
 unsigned int Servo2Delay;

 /* grid.h is calculated by joe2.c */
 #include "grid.h"

 /*--------------------------------------------------------------------initservos
 *  Initialize servo values and set up timers.
 *
 */

 void initservos(unsigned char s0, unsigned char s1, unsigned char s2 ){

	CurrentServo=0;
	SpaceDelay=65535-((20-(NSERVOS*2))*KFREQ)/12;
	Servo0Delay=DegreesX92delay(s0);
	Servo1Delay=DegreesX92delay(s1);
	Servo2Delay=DegreesX92delay(s2);
        // assembly here is
	// mostly to avoid having to define SERVO pins in both c and asxxx
	// eventually may rewrite routine in assembly.

    _asm
	clr	SERVO0
	clr	SERVO1
	clr	SERVO2
    _endasm;
	// should set flags individually to allow for other timer settings
	TMOD=0x01; //#%00000001
	TCON=0x10; //#%00010000

	TH0=0xFE;
	TL0=0;

	IE=0x82; //#%10000010
 }
 /*--------------------------------------------------------------------servopulse
  * pulse servos sequentially.
  *
  */
 void servopulse(void) interrupt 1 _naked
 {
    _asm
    	clr	TR0
	push	ACC
	push	PSW
	push	B
	clr	SERVO0
	clr	SERVO1
	clr	SERVO2
	mov	A,_CurrentServo
	cjne	A, #NSERVOS, $0001
	mov	A, #255
	mov 	TL0,_SpaceDelay
	mov 	TH0,_SpaceDelay+1
	sjmp	$0007
 $0001:  jnz	$0002
	mov 	TL0,_Servo0Delay
	mov 	TH0,_Servo0Delay+1
	setb	SERVO0
	sjmp	$0007
 $0002:  cjne	A, #1,	$0003
	mov 	TL0,_Servo1Delay
	mov 	TH0,_Servo1Delay+1
	setb	SERVO1
	sjmp	$0007
 $0003:	mov 	TL0,_Servo2Delay
	mov 	TH0,_Servo2Delay+1
	setb    SERVO2
 $0007:	inc	A
	mov	_CurrentServo,A
	pop	B
	pop	PSW
	pop	ACC
	setb	TR0
	reti

     _endasm;
 }

 time1ms()    /* not really a 1 ms delay with XTAL 11.0592MHz */
 {
    int i;
    for (i = 0; i < 8 ; i++)
    ;
 }

 void delay(unsigned int n)      /* do nothing n*1ms */
 {
    int i;
    for (i=0; i< n ; i++)
    time1ms();

 }

 unsigned int DegreesX92delay(unsigned int DegreesX9){
 //delay(10);
 return 0-(690+(DegreesX9));
 }

 void shoulder(unsigned int DegreesX9){
 Servo0Delay=DegreesX92delay(DegreesX9 STRIM);
 }
 void elbow(unsigned int DegreesX9){
 Servo1Delay=DegreesX92delay(DegreesX9 ETRIM);
 }
 void xit (unsigned char x,unsigned char y,unsigned int dly){
 unsigned int s,e;
 unsigned char ds,de;
 s=angles[x][y][0];
 e=angles[x][y][1];

 shoulder(s);elbow(e);delay(dly);

 ds=(char) s - angles[x+1][y][0];
 de=(char) e - angles[x+1][y][1]; 

 ds=ds/3;
 de=de/3;

 shoulder(s+ds);elbow(e+de);delay(dly);
 shoulder(s);elbow(e);delay(dly);
 shoulder(s+ds);elbow(e+de);delay(dly);
 shoulder(s);elbow(e);delay(dly);
 shoulder(s+ds);elbow(e+de);delay(dly);
 shoulder(s);elbow(e);delay(dly);
 shoulder(s+ds);elbow(e+de);delay(dly);
 shoulder(s);elbow(e);delay(dly);
 shoulder(s+ds);elbow(e+de);delay(dly);
 }

 #if 0
 #define GOTO(X,Y)  shoulder(angles[X][Y][0]); elbow(angles[X][Y][1]); delay(dly);
 void xit (unsigned char x,unsigned char y,unsigned int dly){
 unsigned char s,e,n;
 for (e=0;e<5;e++){
 GOTO(x-1,y);
 GOTO(x-1,y+1);
 GOTO(x,y+2);
 GOTO(x+1,y+2);
 GOTO(x+2,y+1);
 GOTO(x+2,y);
 GOTO(x+1,y-1);
 GOTO(x,y-1);
 GOTO(x-1,y);
 }
 }
 #endif

 /*----------------------------------------------------------------------------main()
  *
  */

 main(){

  unsigned char d,e,x,y,n;

  initservos(angles[1][1][0],angles[1][1][1],90);
  d=0;e=0;
  for (n=0; n<50; n++){
     for(x=0;x<15;x++){
	 if (d==0){
	     for(y=1;y<12;y++){
	     xit(x,y,500);
	     }
	     d=1;
         } else {
	     for(y=11;y>0;y--){
	     xit(x,y,500);
	     }
	     d=0;
         }
     }
   e=0;
   }
 }