How to program PIC16F877A stepper motor revolution [Full circuit & 3/4 Code]

[slapdash]

Automatic Blind System

Hi there,

I'm currently working on project call automatic blind system which is activate depends on outside condition. Before this is tried to build this project MICROCONTROLLER BASED AUTOMATED LIGHT CONTROL SYSTEM which is based on AVR ATMEGA32 but it failed to get what is has supposed to..

Since that i try to switch to PIC and found out using PBP is time saving and cost reduced language since the project submission is just around the corner..I hope PBP master here can fix my code since i wrote this just a day ago with zero knowledge of PBP by just reviewing the manual and project book. Here is the circuit diagram and code. The proteus VSM files will be PM if someone really want to help.

The Circuit



PicBasic Pro code

'****************************************************************
'*  Name    : 877A_BLIND.BAS                                    *
'*  Author  : PIJO RAHMAN                                       *
'*  Notice  : Copyright (c) 2008 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 11/4/2008                                         *
'*  Version : 1.0                                               *
'*  Notes   : Using PIC16F877A to control Vertical Blind Auto   *
'*            and Manual with light sensor                      *
'****************************************************************
DEFINE OSC 4

'****************************************************************
CMCON = 7
ADCON1 = 7

TRISB = 0 ' Set PortB as output
TRISA = 1 ' Or TRISA = 255, set PortA as input

'***************************************************************
Define  LCD_DREG        PORTD 'Based on Rentron 877A LCD Connection
Define  LCD_DBIT        4
Define  LCD_RSREG       PORTE
Define  LCD_RSBIT       0
Define  LCD_EREG        PORTE
Define  LCD_EBIT        1

B1 VAR BYTE            'Declared Byte For LCD Splash Screen
B0 VAR BYTE 
B2 VAR BYTE 
B3 VAR BYTE 
B4 VAR BYTE 
B5 VAR BYTE 

'****************************************************************
clear                   'clear all variables
LCDOUT $FE,1            'clear lcd
PAUSE 500               'pause for lcd init
Low PORTE.2             'LCD R/W line low (W)
'**************************************************************

'*****************slide text for splash screen**************************
LOOP:
LCDOut $fe,2 
For B2= 0 TO 15 
LookUp B0, ["               AUTOMATIC BLIND SYSTEM              #"], B1  
IF B1 = "#" Then GoTo reset 
LCDOut B1 
B0 = B0 + 1 
Next B2 
pause 125        'character wait time
B0 = B0 - 15 
GoTo loop
RESET:
LCDOUT $FE,1
'************************************************************************

CREDIT:                     'Display Presenter Credit
  LCDOUT $FE,$80
  LCDOUT "PRESENTER NAME"  'presenter  credit
  'LCDOUT $FE,$C0
  'LCDOUT " GROUP   "   'presenter  credit
  PAUSE 1500
  LCDOUT $FE,1

speed var word
speed = 100
;i var byte

Main:                   ' Main Prgm, Check Button for Auto/Manual Op
IF PORTA.0=1 THEN Manual
If PORTA.1=1 Then ForwardM
If PORTA.1=0 Then ReversesM
Goto Main
End

Manual:     'FOR MANUAL OPERATION START WITH RA0=1 THEN CONTROL RA2 AND RA3
Pause 500    'Do it about 2 times a second
LCDOUT $FE,1  'Clear LCD
LCDOUT $FE,$80,"MANUAL"   'Display "Manual" 1st Line on LCD
LCDOUT $FE,$C0,"USER INPUT" 'Display "USER INPUT" 2nd Line on LCD
IF PORTA.2=1 THEN FORWARDM   'Manually Opening Blind
IF PORTA.3=1 Then ReversesM   'Manually Closing Blind
Goto Main

ForwardM:
LCDOUT $FE,1
LCDOUT $FE,$80,"OPENING BLIND"
LCDOUT $FE,$C0,"DAYLIGHT"
;FOR i = 1 TO 5 ' one revolution   'Actually Use this Function for Revolution Step But No LUCK! :(
GOto Forward ' rotate clockwise
;NEXT i
GOTO Main

ReversesM:
LCDOUT $FE,1                        'Clear LCD
LCDOUT $FE,$80,"CLOSING BLIND"
LCDOUT $FE,$C0,"SUNSET/DARK"
;FOR i = 1 TO 5 ' one revolution
Goto Reverses ' rotate counter-clockwise
;NEXT i
GOTO Main

Forward:     'Stepper Motor Clockwise Sequence
portb = %1100
pause speed
portb = %0110
pause speed
portb = %0011
pause speed
portb = %1001
pause speed
Goto Main

Reverses:        'Stepper Motor AntiClockwise Sequence
portb = %1001
pause speed
portb = %0011
pause speed
portb = %0110
pause speed
portb = %1100
pause speed
Goto Main
END

The operation

This project is simple as it shows. The circuit is consist of manual and automatic function. SW1 connected at RA0 is to use to switch between auto/manual mode. In auto mode, all the manual control switch which is SW3 and SW4 is not activated but only receive the signal from SW2 [which is will be interface to light-dark activated switch, so no ADC will be required]. If SW2 high, motor is rotate clockwise and the blind is open, but if SW2 low, motor is rotate anticlockwise and the blind is close.It need 10 stepper motor revolution [according to my blind] to open and close the blind slat, which is i dunno how to program it. ... so even the switch is still in high, the stepper only rotate 10 times and stop and wait till the other state. The stepper motor that I use is common 1.8 degree per step.

The operation repeated until someone invoke the manual switch.

Other switch which is SW5-SW6 is to use to control blind vertical position by using simple DC motor interface to L293D which is will be added later on. The LCD 16x2 is only to display operations, since PIC16F877A still have the unused port.

p/s: If someone interested in this project or feel free to help, just pm me to get the proteus VSM files. Since the dateline is only a week, I hope someone can help me urgently..Thanks in advance!

[mackrackit]

I am most likely missing something, but what about this

ForwardM:
LCDOUT $FE,1
LCDOUT $FE,$80,"OPENING BLIND"
LCDOUT $FE,$C0,"DAYLIGHT"
FOR i = 1 TO 500 ' ?? will equal 10 revolutions ??
portb = %1100
pause speed
portb = %0110
pause speed
portb = %0011
pause speed
portb = %1001
pause speed
NEXT i
GOTO Main

[Melanie]

Unless you are counting steps (and have limits preset), I see no way of detecting end of travel of your blind, which means you can drive it beyond it's stop position in either open or close mode.

[slapdash]

I am most likely missing something, but what about this

ForwardM:
LCDOUT $FE,1
LCDOUT $FE,$80,"OPENING BLIND"
LCDOUT $FE,$C0,"DAYLIGHT"
FOR i = 1 TO 500 ' ?? will equal 10 revolutions ??
portb = %1100
pause speed
portb = %0110
pause speed
portb = %0011
pause speed
portb = %1001
pause speed
NEXT i
GOTO Main

I tried this code but the motor also seems to rotate without stop.

Unless you are counting steps (and have limits preset), I see no way of detecting end of travel of your blind, which means you can drive it beyond it's stop position in either open or close mode.

I thought it's possible to count the motor step (limit the step). Is there anyway to achieve this?

I've thinking again, how about use the inside sensor, double the sensor to set the stop position. When the blind is open and the 2nd sensor which is located in the room detect the light, it will stop the motor. This is meant the 1st sensor use to start the motor and 2nd sensor use to stop the motor.

Same thing goes to close operation. if the outside = 0 and the inside = 0 the blind will close.

to summary this,

open operation:

1st sensor = 1 (motor start) then 2nd sensor = 1 (motor stop)

close operation:

1st sensor = 0 (motor start) then 2nd sensor = 0 (motor stop)

My question is, how can i use any label that prevent the motor spinning like the stop/pause function?

[mackrackit]

I tried this code but the motor also seems to rotate without stop.

I forgot to say i needs to be a word size variable, as a byte it can never reach 500

I thought it's possible to count the motor step (limit the step). Is there anyway to achieve this?

If you do not have a preset limit like Melanie mentioned you can make the stepper stop, but it may not always stop in the exact same place. If there is some drag on the mechanism for example.

You could use a light sensor, but what if there is enough light to start but not stop. Or attach a couple of micro limit switched that a hit on full open or full close. There are many ways to make some sort of encoder. If the blind are only rotating 90 degrees a pot fixed to a blade may work.

[mister_e]

I forgot to say i needs to be a word size variable

Really ??? Everyone have it's own project

[mackrackit]

Really ??? Everyone have it's own project

Every one is a smart _ _ _

The variable "i" needs to be WORD sized.

[Archangel]

<b>Open Loop Solution</b>
How powerful is that stepper motor? You know what happens to a stepper motor when it stalls? At worst it demagnetizes, at best, nothing.
Stepper motors have no commutator, no brushes, no sparks, no increase in current (to speak of), very unlike a brushed motor which gets very Ticked Off when it stalls. So here is a thought, rig up a counter and count the steps between the ends of travel, and drive your motor that many steps + a few extra.

[Charles Linquis]

A common trick is to logically AND the limit switches with one of the phases.
That way the stepper will always stop in the same place, and the position sensitivity of the limit switch (or opto) is decreased by at least 4.

This is easy to do in software.

[aratti]

Slapdash, I don't know what kind of blind you are trying to move with a unipolar stepper motor. They should be very light!

Remember that to use an open loop system (relying only on the steps count) with a minimum of confidence, you should use at maximum half the torque the motor can produce.

Even so every open loop system has at least one switch for the zero position. This means that at power up the system search for the zero and set the internal counter offsetting possible drift.
You are using a unipolar stepper which I doubt has the necessary torque for your application, so very likely you will need a gearbox to increase the mechanical torque at the expense of the speed.
Naturally the number of steps per turn of the gearbox shaft should take into account the gearbox ratio.

Further more I suggest you to take into seriuos consideration the needs of two limit switches.

If you could let us know what kind of blind you are moving and the type of stepper you are using it will make life easier in helping you.

Al.

[slapdash]

Slapdash, I don't know what kind of blind you are trying to move with a unipolar stepper motor. They should be very light!

Remember that to use an open loop system (relying only on the steps count) with a minimum of confidence, you should use at maximum half the torque the motor can produce.

Even so every open loop system has at least one switch for the zero position. This means that at power up the system search for the zero and set the internal counter offsetting possible drift.
You are using a unipolar stepper which I doubt has the necessary torque for your application, so very likely you will need a gearbox to increase the mechanical torque at the expense of the speed.
Naturally the number of steps per turn of the gearbox shaft should take into account the gearbox ratio.

Further more I suggest you to take into seriuos consideration the needs of two limit switches.

If you could let us know what kind of blind you are moving and the type of stepper you are using it will make life easier in helping you.

Al.

I'm using vertical blind.

[aratti]

Good to know.

Did you try to pull your blind up with the stepper and with 500 mA max current you can supply to your stepper ?
(I suggest you to replace the ULN2003a with ULN2803a. This has 8 transitors, you can parallel them obtaining 4 couples and doubling the output current in this way)

Is it working ?

Does the stepper run smoothly ?

Can you install the two limit switches?

Al.