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LIFT USING STEPPER MOTOR  

 

Introduction

MICROCONTROLLER BASED LIFT CONTROL SYSTEM.

 

 In this project we show that how we control the lift system with the help of advance microcontroller  89c51. Designing of lift system is really not possible with the help of the simple electronics circuit. Its look very easy when we use a microcontroller system with this project.

 

In this lift there is total 4 floor . Ground floor and other three floor and total is four floor.  And there is one platform, which is run by a stepper motor. Here we use stepper motor to lift the down the platform.

 

Total four switch is connected to this project  for four floor. Four reed sensor is connected to the each floor.

 

Here we use one microcntroller  to control all the function of the  lift.

Here we use ic 89c51 . 89c51 is a 40 pin ic. Pin no 40 is connected to the positive supply and pin no 20 is connected to the ground pin.  In this micrcontroller there is total 4 ports. Port 0, Port1, Port2, Port3.

 

Stepper motor is connected to the port 0. Pin no 39,38, 37,36 is connected to the ic 4049. Output of the micrcontroller is active low , so to convert this o logic into 1 logic we use  ic 4049.. Pin no 1 is connected to the positive supply.  Pin no 3,5,7,9. is connected to the input pins of the inverter ic. This ic is a hex inverter ic. Output of this ic is  inverted. To convert the output from the micrcontroller   to active high we use ic 4049. Output of the ic 4049 is now connected to the   driver transistor through 100 ohm resistor and l.e.d.s resistor 100 ohm and led  in series give a low voltage to the base of the npn transistor and transistor work as a switch . Here four transistor control  the   four coils of the stepper motor.

 

Output of the stepper motor is further connected to the gear bos. Gear box reduce the speed of the stepper motor and hece increase the torque also. With the help of this torque we lift the motor as per the requirement.

 

Port 0 is also connected by a pull up resistor 10 k ohm. Whenever we connect a port 0 to any outer circuit then pull up resistor is very mch necessary.

 

Input switches is connected to the  port 1 . four bits of port 1 is connected to the  input switches and four bits  is connected to the  reed sensor. By this input switches we move the lift on desired position and with the help of this reed sensor we  sense the position of the lift on the floor.

 

Port 2 is connected to the seven segment decoder. When lift sense the redd sensor at that time bcd output is available on this output and  ic 7447 converts the bcd input into a seven segment decoder. Output of the seven segment decoder is further connected to the  common anode  led display. 

 

 

On default when we switch on the  lift then lift came back on the ground floor and  after then we press any switch then lift start automatically and give a  sequential voltage to the stepper motor through inverter ic. Processor count the steps on call and stop automatically  after predetermined steps. When we call the lift on any floor then processor firstly sense  the lift position with the help of the reed  sensor and then from that postion automatically  decide the direction and  sense the input calling switch. On the calling switch , processor decide the steps and then stop automatically. When lift move up and down then its passes through the reed sensor and sense the input and display it on the  led display.  Sensing of the  floor is decided by the reed sensor and  magnet , which is fitted on the  lift platform.

 

 

Complete software is to be written in the machine language. In the programming firstly we intialize all the ports   with there inputs and outputs.

 

 

Onm default our program is start from the 0rg 000h and after then it jumps to the  main  function. This main function is started from org 30 h. From org 000h to org 30h is for  intruppt handling. All the intruppts are placed in the space , so in the programming we always ignore this location and start from org 30 h.

 

Main:

          Mov p0,#066h

          Mov p1,#0ffh

          Mov p2,#0ffh

          Mov p3,#0ffh

 

Here stepper motor is connected to the port 0 so we give a initial value to the  stepper motor to give a starting torque to the motor with the help of 066h value.

Port P1, port  P2 and port P3 is also  put a value 0ffh. . Note that we take a 0 output from the microcontroller so we always  in starting give value 1 on the these output port.

 

Components required:

Item

qty

Rate/piece

In89c2051

1

60

Crystal 12Mz

1

25

motors

2

250*2

Ic base

1

10

Transformer 0-12v 500mA

1

50

photodiode

3

25*3

optocoupler

4

4*10

Tr 548

4

2*4

Tr 558

4

2*4

Resistances 10k

10

2

Capacitor

1

10

 

Bibliography:

www.mcuproject.com/pro.html

www.ludhianaprojects.com/mc.html