The document discusses interfacing a stepper motor with an 8051 microcontroller. A stepper motor can divide a full rotation into discrete steps through energizing coils in different sequences. The stepper motor can be interfaced with an 8051 using an L293D motor driver connected to ports P1.0, P1.2, P1.3, and P1.4 of the 8051. Both full-step and half-step sequences are described for energizing the coils to precisely control the motor's position without feedback. Assembly and C code examples are provided to demonstrate clockwise and counterclockwise rotation of the stepper motor connected to the 8051.

1. Interfacing Stepper Motor with 8051 www.pantechsolutions.net

3. The motor's position can be controlled precisely without any feedback mechanism, as long as the motor is carefully sized to the application.

4. Stepper motors are similar to switched reluctance motor (which are very large stepping motors with a reduced pole count, and generally are closed-loop

5. The stepper motor can be interfaced with the 8051 using l293d connected to p1.0,p1.2,p1.3,p1.4

6. Stepper motor two types of step sequence 1) full step and 2) half step sequence

7. In the full step sequence, two coils are energized at the same time and motor shaft rotates. The order in which coils has to be energized is given in the table belowWHAT IS STEPPER MOTOR ?

8. Full step and half step sequence In the full step sequence, two coils are energized at the same time and motor shaft rotates. The order in which coils has to be energized is given in the table below. In Half mode step sequence, motor step angle reduces to half the angle in full mode. So the angualar resolution is also increased i.e. it becomes double the angular resolution in full mode. Also in half mode sequence the number of steps gets doubled as that of full mode. Half mode is usually preffered over full mode. Table below shows the pattern of energizing the coils.

9. Full step sequence

10. Full step sequence

11. Half step sequence

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13. Half step sequence

14. org0Hstepper equP1main: mov stepper,#0CH acall delay mov stepper,#06H acall delay mov stepper,#03H acall delay mov stepper,#09H acall delay sjmp main STEPPER MOTOR ASSEMBLY CODE

15. delay: mov r7,#4wait2: mov r6,#0FFHwait1: mov r5,#0FFHwait: djnz r5,wait djnz r6,wait1 djnz r7,wait2 ret end ASSEMBLY CODE CONTD

16. #include <reg51.h> //Define 8051 registers #include<stdio.h> void DelayMs(unsigned int); //Delay function void Clockwise (void) { unsigned int i; for (i=0;i<30;i++) { P0 = 0x01;DelayMs(5); //Delay 20msec P0 = 0x02;DelayMs(5); P0 = 0x04;DelayMs(5); P0 = 0x08;DelayMs(5); } } STEPPER MOTOR C CODE

17. void AntiClockwise (void) { unsigned int i; for (i=0;i<30;i++) { P0 = 0x08;DelayMs(5); //Delay 20msec P0 = 0x04;DelayMs(5); P0 = 0x02;DelayMs(5); P0 = 0x01;DelayMs(5); } } void main (void) { P0 = 0; //Initialize Port0 C CODE CONTD

18. C CODE CONTD while(1) //Loop Forever { Clockwise (); DelayMs (100); P0 = 0; AntiClockwise (); DelayMs (100); P0 = 0; } } void DelayMs(unsigned int n) {

19. unsigned int i,j; for(j=0;j<n;j++) { for(i=0;i<800;i++); } } C CODE CONTD

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