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

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- 4th November 2008, 09:46
slapdash

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

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

http://i284.photobucket.com/albums/l...77Acurtain.png

PicBasic Pro code

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!
- 4th November 2008, 13:21
mackrackit

I am most likely missing something, but what about this

Code:

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
- 4th November 2008, 17:03
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.
- 4th November 2008, 19:05
slapdash

Quote:

Originally Posted by mackrackit

I am most likely missing something, but what about this

Code:

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.

Quote:

Originally Posted by 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.

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?
- 4th November 2008, 21:10
mackrackit

Quote:

Originally Posted by slapdash

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

Quote:

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.
- 4th November 2008, 21:16
mister_e

Quote:

Originally Posted by mackrackit

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

Really ??? Everyone have it's own project :D
- 4th November 2008, 21:29
mackrackit

Quote:

Originally Posted by mister_e

Really ??? Everyone have it's own project :D

Every one is a smart _ _ _ :D

The variable "i" needs to be WORD sized. :D
- 5th November 2008, 04:18
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.
- 5th November 2008, 04:49
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.
- 5th November 2008, 22:31
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.
- 6th November 2008, 07:30
slapdash

Quote:

Originally Posted by 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.

I'm using vertical blind.
- 6th November 2008, 10:27
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.