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Interface of Stepper motor with Microcontroller

 Implementation of Interface of Stepper Motor with Microcontroller ,Hardware and Software sides

Now we will proceed towards the real implementation of interface of stepper motor with microcontroller and will complete its hardware and software sides one by one.

Hardware of Stepper Motor (Electronics Circuit design)

The hardware of this project is consists of three major portion as described below:

  1. Microcontroller: The necessary components used to operate the microcontroller to do some useful tasks in accordance with the coding in it.
  2. The serial communication circuit around RS-232
  3. Power connection and Power  driver circuit of stepper motor which accept commands from microcontroller and operate the stepper motor accordingly.
The circuit around microcontroller is very simple, it needs very  basic components to operate like, crystal with two capacitors and power on reset which is consist of a resistor and capacitor. Rest is power supply +5V DC.
The circuit around RS-232 for serial communication is very simple, one MAX-232 or RS-232 IC chip and four 10uf/16 capacitors.
These are shown in complete circuit diagram in figure-2 at the  middle of the post. Now we discuss the main power driver module or circuit for control of stepper motor.

Power Driving Circuit for stepper Motor

It is normal practice that the steppers motors draw high currents as compared to other motor of same size. It is therefor need to be operated through a power driver circuit. In our case the stepper motor we are using in this project takes 0.4 to 2.0 Ampere current i.e. 0.2 ampere per coil in pull-out state and 1 ampere per coil in hold state. Therefor we have designed a power driver circuit for it which includes TIP 121 NPN to provide the high current to the coils of stepper motor. The TIP-121 NPN transistors is actually a Darlington Silicon power transistor. The electronics connection diagram has been shown in figure below.

Stepper motor Power driver circuit
Power driver circuit diagram for Stepper motor connection with microcontroller At89c51

Complete circuit diagram of the Microcontroller Project:

The complete circuit diagram of this project includes all the three parts as discussed earlier i.e circuit around microcontroller, circuit around RS-232 and power driver circuit. The complete circuit diagram of stepper motor control using microcontroller 8051 is shown in figure below.
stepper motor complete circuit 8051
stepper motor controller circuit diagram 8051 RS232 serial port

Software of Stepper motor project:

The software side of this project is consist of two parts as below:
  1. The program written C++ language to be run inside PC for serial communication with Microcontroller for the effective control of stepper motor.
  2. The program written in assembly language for microcontroller to implement the desire task.
Both of the codes are provided in this tutorial for the understanding of student.

The C++ Code for serial communication and Stepper motor control

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#include<constream.h> // Builin Libraries of the compiler
#include<stdio.h>
#include<dos.h>
#define COM1 0x2F8 // serial port number 
void send_data(char rotations, char steps, char control,char delay_low,char delay_high);
void main(){
	int rotations,steps,control,sps,*ptr;
	int i,j,k,l,m;
	float rpm;
	char  rots,stps,ctrl,*chr_ptr,delay_low,delay_hi;
	/* port Initialization*\
	outportb(COM1+1, 0);            // Turn off interrupts - port1
	outportb(COM1+3, 0x80);         // Set DLAB ON
	outportb(COM1+0, 0x0C);     	// Set baud rate - Diviser latch low byte
	outportb(COM1+1, 0x00);         // Set baud rate - Diviser latch high byte
	outportb(COM1+3, 0x03);         // 8-bit no parity mode
	outportb(COM1+2, 0xC7);         // FIFO Control Register
	outportb(COM1+4, 0x0B);	        // Turn on DTR, RTS and OUT2
	clrscr();
	printf("\n            Control Program");
	printf("\n           ====== =======\n\n\n\n");
	do{
		printf("Enter No of rotation [0-255]  ");
		scanf("%d",&rotations);
	}
while(rotations<0 || rotations>255);
	rots=(char)rotations;
	do{
		printf("\nEnter No of Steps    [0-200]  ");
		scanf("%d",&steps);
	}
while(steps <0 || steps>200);
	stps=(char)steps;
 	do{
		printf("\nEnter RPM            [60-240] ");
		scanf("%f",&rpm);
	}
while(rpm<60.00 || rpm>240.00);
	do{
		printf("\nEnter Direction");
		printf("\n0 for Clockwise");
		printf("\n1 for Counter Clockwise       ");
		scanf("%d",&control);
	}
while(control <0 || control >1);
	ctrl=(char)control;
	sps=int(1000000/(rpm*6/1.8));
	sps=-0.9*sps;
	ptr=&sps;
	chr_ptr=(char *)ptr;
	delay_low=*chr_ptr;
	delay_hi=*((char *)chr_ptr+1);
	// call_send data to send data to serial port
	send_data(rots,stps,ctrl,delay_low,delay_hi);
	getch();
}
void send_data(char rots,char stps, char control,char delay_low,char delay_high)
{
	outportb(COM1,delay_high); 	    //send delay high byte
	for (int i=1 ;i<1000;i++);
	outportb(COM1,delay_low);       //send delay low byte
	for (i=1 ;i<1000;i++);
	outportb(COM1,control);         //send control byte
	for (i=1 ;i<1000;i++);
	outportb(COM1,stps);             //send number of steps
	for (i=1 ;i<1000;i++);
	outportb(COM1,rots);             //sendt number of rots
	}


The Assembly Language program for Microcontroller 8051.


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;MAIN PROJECT PROGRAM
ORG 00H				
SJMP MAIN;			DIRECTING PROGRAM FLOW TO MAIN
ORG 0023H
LJMP SP_ISR;			DIRECTING SERIAL PORT INTERUPPT TO ROUTINE
ORG 0030H
MAIN:
	MOV IE,#90H;		ENABLE SERIAL PORT INTERRUPT			
	MOV SCON, #50H;		SET SERIAL PORT MODE 1 AND ENABLE 	RECIVE DATA	
	MOV TMOD, #21H;		SET TIMER 1 IN MODE 2 AND TIMER 0 IN 	MODE 1
	MOV TH1, #-3;		SET TIMER 1 HIGH BYTE FOR 9600 BAUD RATE
	MOV R0,#05H;		SET REGISTER R0-R5 TO THEIR INITIAL VALUES
	MOV R1,#00H;		
	MOV R2,#00H;
	MOV R3,#00H;
	MOV R4,#00H;
	MOV R5,#00H;
	CLR F0;			CLEAR THE BIT F0;
	MOV A,#96H;		LOAD ACCUMULATER WITH INITIAL CONDITION
	SETB TR1;		START TIMER 1
RUN:	JNB F0,RUN;		WAIT UNTIL F0 GET SET
	JMP  ROTS;		JUMP TO ROTS ROUTINE WHEN F0=1
STP:	MOV B,R2;		MOVE THE CONTENTS OF R2 TO R6
	MOV R6,B;
	MOV R2,#00H;		JUMP TO STEP: TO COMPLETE THE NO OF STEPS
	JMP STEPS;
FINISH:	CLR F0;			CLEAR F0 WHEN ALL THE ROTATIONS AND STEPS ARE COMPLETE
	SETB P2.0;		
	SJMP RUN;		GO TO RUN AND WAIT TILL THE NEW INPUT FROM PC IS RECIVED
ROTS:
	INC R1;
	DJNZ R1,GO_ROTS;	CHECK IF NO OF ROTATIONS ARE ZERO IF YES GO FOR STEPS
	JMP STP; 
GO_ROTS:
	INC R3
	DJNZ R3, CLK_WSE_ROT;	GO FOR CLOCK WISE ROTATIONS
	JMP ANT_CLK_ROT;	GO FOR ANTI-CLOCK WISE ROTATIONS
STEPS:	
	INC R6			
	DJNZ R6,GO_STEPS;	CHECK IF NO: OF STEPS ARE ZERO IF YES GO FOR FINISH
	JMP FINISH;
GO_STEPS:
	INC R3
	DJNZ R3, CLK_WSE;	GO FOR CLOCK WISE STEPS
	JMP ANT_CLK;		GO FOR ANTI-CLOCK WISE STEPS
CLK_WSE_ROT:			
	MOV R6,#200;		LOAD R6 WITH INITIAL VALUE OF 200 STEPS FOR ONE STEPS
SP1:	MOV P1,A;		LOAD PORT WITH INITIAL VALUE	
	RL A;			GENERATE NEW VALUE FOR PORT 1 FOR CLOCKWISE DIRECTION
	RL A;
	CALL DELAY;		WAIT FOR DELAY BETWEEN TWO STEPS
	DJNZ R6,SP1;		CHECK IF ONE ROTATION IS COMPLETE
	DJNZ R1,CLK_WSE_ROT;	CHECK IF TOTAL ROTATIONS ARE COMPLETE
	JMP STP
ANT_CLK_ROT:
	MOV R6,#200;		LOAD R6 WITH INITIAL VALUE OF 200 STEPS FOR ONE STEPS
SP2:	MOV P1,A;		LOAD PORT WITH INITIAL VALUE
	RR A;			GENERATE NEW VALUE FOR PORT 1 FOR ANTI_CLOCKWISE DIRECTION	
	RR A;			
	CALL DELAY;		WAIT FOR DELAY BETWEEN TWO STEPS	
	DJNZ R6,SP2;		CHECK IF ONE ROTATION IS COMPLETE
	DJNZ R1,ANT_CLK_ROT;	CHECK IF TOTAL ROTATIONS ARE COMPLETE
	JMP STP;
CLK_WSE:
JMP CLK_WSE_STEPS;		

CLK_WSE_STEPS:			
	MOV P1,A;		
	RL A;
	RL A
	CALL DELAY;
	DJNZ R6,CLK_WSE_STEPS;
	JMP FINISH
ANT_CLK:
	JMP ANT_CLK_STEPS;
ANT_CLK_STEPS:
	MOV P1,A;
	RR A;
	RR A;
	CALL DELAY;
	DJNZ R6,ANT_CLK_STEPS;
	JMP FINISH;
DELAY:
 	MOV TH0,R5;		LOAD TIMER 1 WITH DELAY VALUES
	MOV TL0,R4;		
	SETB TR0;		
HERE: 	JNB TF0,HERE;		WAIT FOR TIMER OVERFLOW
	CLR TR0;		CLR TR0
	CLR TF0;		STOP TIMER1
	RET;			RETURN TO THE CALLING INSTRUCTION	
SP_ISR:
	MOV @R0,SBUF;		RECIVE DATA FROM SERIAL PORT
	CLR RI;			CLEAR RECIVE INTERRUPT BIT
	DJNZ R0,RETU;		CHECK IF ALL THE FIVE DATAS ARE RECIVED
	MOV R0,#05;		LOAD R0 WITH INTIAL VALUE 	
	CLR P2.0
	SETB F0;		SET F0
RETU:
	RETI;			RETURN FROM INTERRUPT

END
at

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