Stepper motor - Electronic Circuits Projects Diagrams Free

uaefame · 11th July 2008, 09:46 PM

This is my schematic that i am using to drive a bipolar stepper motor. The thing is i want to know what wrong with it?

Here is the connection:Electronic Circuits Projects Diagrams Free - uaefame's Album: Circuits - Picture

Q1> Do i need to connect a 10k resistor between the 16F84a and sn754410 pins 2,7,9 and 15 or leave it as it is?

Q2> I am using same power source for Vcc1 and Vcc2 does it matter because the pic need 5V and the stepper need 5V same volt why get a new power source?

Q3> The motor behavior is strange going back and forth, its strange if you spot any mistake in the schematic let me know?

Thanks in advance

Mikebits · 11th July 2008, 10:08 PM

Try adding more DC filtering around VCC2.

uaefame · 11th July 2008, 10:22 PM

What does that suppose to do dc filtering?

Do you mean i add capacitor or something?

Mikebits · 11th July 2008, 10:34 PM

Yeah, caps. I would add a 10uf cap right at the reg output. I would also put a .01 cap near the PIC power pin. And caps around the VCC1 and 2 pins. DC supply noise causes erratic behavior. It is just good practice to use good DC filtering.

Mikebits · 11th July 2008, 10:37 PM

This link looks useful.
Interface to a motor controller

uaefame · 12th July 2008, 05:54 PM

Do you mean i connect between VCC2 and ground a capacitor of 10 or 0.01uF. Same goes to the VCC1 and ground another 0.01 or `10 uF.

Q1> Is this the proper way to connect them?

At the output of the voltage regulator and pic power supply there are alreay capacitor there.

I already did this but nothing work still same problem? Did i understand dc filtering wrong?

Thanks in advance

Mikebits · 12th July 2008, 08:05 PM

I just noticed something, why are you not connecting the enable pins. They should not be floating.

yngndrw · 12th July 2008, 08:33 PM

Yes, enable pins need to be tied to VCC1 via a 10k resistor.

You also don't seem to be implementing any current limiting - If you use a higher voltage than the motor's rated voltage (About 10x higher max !) and limit the current to the rated current for the motor you will get much more torque.

The only reason my stepper motors oscillate around the same point are because I've reached the torque limit. Remember that as speed goes up, torque goes down for a stepper motor.

You might also want to think about adding some protection diodes to the outputs, depending on the size of your motor. (The driver already has some.)

uaefame · 12th July 2008, 09:21 PM

Here is my additions to the previous circuit after taking into consideration yngdrw and mikebits suggestions. Still the motor osicilates in the same place. The only thing i didn't add until now is diodes as mentioined yngdrw and in sn754410 there are internal diodes but adding more diodes will not hurt for the time being i will stick without diode.

Here is my Electronic Circuits Projects Diagrams Free - uaefame's Album: Circuits - Picture

Sorry for my poor knowledge in electrical but with ur helps, I can one day help as may as i can maybe to you guys as well because i have strong (solid) knowlege in other fields.

Any suggestion is welcomed and will be looked into it.

Thanks in advance

yngndrw · 12th July 2008, 09:32 PM

You only need one resisotr for the enable pins. Tie both enable pins together then use a single 10k resistor to VCC1.

Double check that the motor coils are connected as you expect them to be.

Post the code that you're using on your PIC, maybe that is wrong ?

Do you have any load on the motor ?

Mikebits · 12th July 2008, 10:03 PM

Perhaps your stepper needs more current than your regulator can supply. Have you measured your supply voltages? Maybe as a test, you can run VCC2 from seperate supply.

uaefame · 12th July 2008, 10:04 PM

Thanks yngndrw,

1) I removed the extra resistor 10K and i connected it as you told me hereElectronic Circuits Projects Diagrams Free - uaefame's Album: Circuits - Picture

2)The motor coil is fine i double check it again and again

3)The codes are here

Code:

LIST	P=PIC16F84A
	#INCLUDE "P16F84A.INC"
	__CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _XT_OSC
	errorlevel -302

	cblock	0x0c
	d1,d2,d3
	endc

	org	0
init
	banksel	TRISA		;bank 1
	clrf	TRISA
	clrf	TRISB
	banksel	PORTB		;bank 0
	clrf	PORTB
main	movlw	b'00000001'
	movwf	PORTB
	call	Delay8ofsec
	movlw	b'00000100'
	movwf	PORTB
	call	Delay8ofsec
	movlw	b'00000010'
	movwf	PORTB
	call	Delay8ofsec
	movlw	b'00001000'
	movwf	PORTB
	goto	main

Delay8ofsec
			;124993 cycles
	movlw	0xA6
	movwf	d1
	movlw	0x62
	movwf	d2
Delay8ofsec_0
	decfsz	d1, f
	goto	$+2
	decfsz	d2, f
	goto	Delay8ofsec_0

			;3 cycles
	goto	$+1
	nop

			;4 cycles (including call)
	return



	end

4) Nothing is connected to the stepper motor in term of loads

I wish these information can help you figure what wrong

Thanks in advance

yngndrw · 12th July 2008, 10:33 PM

Ah, you only have one coil energised at a time. Because of the driver IC and that fact that the enable pins are not used, this means that the second coil acts as a break.

Try:
00000101
00000110
00001010
00001001

I think that's the reason anyway.

uaefame · 12th July 2008, 10:44 PM

Hello yngndrw,

I did as you said but the problem still the same moving back and forth

Here are the updated codes

Code:

LIST	P=PIC16F84A
	#INCLUDE "P16F84A.INC"
	__CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _XT_OSC
	errorlevel -302

	cblock	0x0c
	d1,d2,d3
	endc

	org	0
init
	banksel	TRISA		;bank 1
	clrf	TRISA
	clrf	TRISB
	banksel	PORTB		;bank 0
	clrf	PORTB
main	movlw	b'00000101'
	movwf	PORTB
	call	Delay8ofsec
	movlw	b'00000110'
	movwf	PORTB
	call	Delay8ofsec
	movlw	b'00001010'
	movwf	PORTB
	call	Delay8ofsec
	movlw	b'00001001'
	movwf	PORTB
	goto	main

Delay8ofsec
			;124993 cycles
	movlw	0xA6
	movwf	d1
	movlw	0x62
	movwf	d2
Delay8ofsec_0
	decfsz	d1, f
	goto	$+2
	decfsz	d2, f
	goto	Delay8ofsec_0

			;3 cycles
	goto	$+1
	nop

			;4 cycles (including call)
	return



	end

Thanks in advance for any suggestion

yngndrw · 12th July 2008, 11:00 PM

Maybe I got the order wrong, try:
00000101
00000110
00001001
00001010
(Swapped the last two lines.)

How long is the delay ? (I'm not an asm person...) Try using a very slow delay if you're using a fast one - It may be too fast. (0.5 seconds, etc.) You could also make it only step on when a button is pressed - Then you can check all of the outputs with a multimeter.

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11th July 2008, 09:46 PM	(permalink)
uaefame	Stepper motor This is my schematic that i am using to drive a bipolar stepper motor. The thing is i want to know what wrong with it? Here is the connection:Electronic Circuits Projects Diagrams Free - uaefame's Album: Circuits - Picture Q1> Do i need to connect a 10k resistor between the 16F84a and sn754410 pins 2,7,9 and 15 or leave it as it is? Q2> I am using same power source for Vcc1 and Vcc2 does it matter because the pic need 5V and the stepper need 5V same volt why get a new power source? Q3> The motor behavior is strange going back and forth, its strange if you spot any mistake in the schematic let me know? Thanks in advance __________________ Hesham Ismail Mohammed Sharif Thank me if you want

11th July 2008, 10:08 PM	(permalink)
Mikebits	Try adding more DC filtering around VCC2.

11th July 2008, 10:22 PM	(permalink)
uaefame	What does that suppose to do dc filtering? Do you mean i add capacitor or something? __________________ Hesham Ismail Mohammed Sharif Thank me if you want

11th July 2008, 10:34 PM	(permalink)
Mikebits	Yeah, caps. I would add a 10uf cap right at the reg output. I would also put a .01 cap near the PIC power pin. And caps around the VCC1 and 2 pins. DC supply noise causes erratic behavior. It is just good practice to use good DC filtering.

11th July 2008, 10:37 PM	(permalink)
Mikebits	This link looks useful. Interface to a motor controller

12th July 2008, 05:54 PM	(permalink)
uaefame	Do you mean i connect between VCC2 and ground a capacitor of 10 or 0.01uF. Same goes to the VCC1 and ground another 0.01 or `10 uF. Q1> Is this the proper way to connect them? At the output of the voltage regulator and pic power supply there are alreay capacitor there. I already did this but nothing work still same problem? Did i understand dc filtering wrong? Thanks in advance __________________ Hesham Ismail Mohammed Sharif Thank me if you want Last edited by uaefame; 12th July 2008 at 05:59 PM.

12th July 2008, 08:05 PM	(permalink)
Mikebits	I just noticed something, why are you not connecting the enable pins. They should not be floating.

12th July 2008, 08:33 PM	(permalink)
yngndrw	Yes, enable pins need to be tied to VCC1 via a 10k resistor. You also don't seem to be implementing any current limiting - If you use a higher voltage than the motor's rated voltage (About 10x higher max !) and limit the current to the rated current for the motor you will get much more torque. The only reason my stepper motors oscillate around the same point are because I've reached the torque limit. Remember that as speed goes up, torque goes down for a stepper motor. You might also want to think about adding some protection diodes to the outputs, depending on the size of your motor. (The driver already has some.) Last edited by yngndrw; 12th July 2008 at 08:34 PM.

12th July 2008, 09:21 PM	(permalink)
uaefame	Here is my additions to the previous circuit after taking into consideration yngdrw and mikebits suggestions. Still the motor osicilates in the same place. The only thing i didn't add until now is diodes as mentioined yngdrw and in sn754410 there are internal diodes but adding more diodes will not hurt for the time being i will stick without diode. Here is my Electronic Circuits Projects Diagrams Free - uaefame's Album: Circuits - Picture Sorry for my poor knowledge in electrical but with ur helps, I can one day help as may as i can maybe to you guys as well because i have strong (solid) knowlege in other fields. Any suggestion is welcomed and will be looked into it. Thanks in advance __________________ Hesham Ismail Mohammed Sharif Thank me if you want Last edited by uaefame; 12th July 2008 at 09:22 PM. Reason: Grammer

12th July 2008, 09:32 PM	(permalink)
yngndrw	You only need one resisotr for the enable pins. Tie both enable pins together then use a single 10k resistor to VCC1. Double check that the motor coils are connected as you expect them to be. Post the code that you're using on your PIC, maybe that is wrong ? Do you have any load on the motor ?

12th July 2008, 10:03 PM	(permalink)
Mikebits	Perhaps your stepper needs more current than your regulator can supply. Have you measured your supply voltages? Maybe as a test, you can run VCC2 from seperate supply.

12th July 2008, 10:33 PM	(permalink)
yngndrw	Ah, you only have one coil energised at a time. Because of the driver IC and that fact that the enable pins are not used, this means that the second coil acts as a break. Try: 00000101 00000110 00001010 00001001 I think that's the reason anyway. Last edited by yngndrw; 12th July 2008 at 10:33 PM.

12th July 2008, 11:00 PM	(permalink)
yngndrw	Maybe I got the order wrong, try: 00000101 00000110 00001001 00001010 (Swapped the last two lines.) How long is the delay ? (I'm not an asm person...) Try using a very slow delay if you're using a fast one - It may be too fast. (0.5 seconds, etc.) You could also make it only step on when a button is pressed - Then you can check all of the outputs with a multimeter. Last edited by yngndrw; 12th July 2008 at 11:01 PM.