3 Axis Stepper Control

[s.k.sahoo]

Hello,
I am sks want to build 3 Axis Stepper Drive, i don't have a detail Schematic.
It will be a great help, if some one can help regarding drawing or providing a Schematic.

Thanks
With best regards
sks

[Enamul]

Hi SKS,
First of all we need to know couple of information regarding the stepper motor you are going to use. I mean we need to know the specification of the stepper motor. Mainly we need to know you are looking for Bipolar drive or Unipolar drive? Half-step, Full-step or Micro-step?
For schematic we need to know the current rating of the motors you are going to use.

[Enamul]

Hi SKS,
You can have a look in the following links..to get some idea..
http://electronics-diy.com/stepper_motors.php
http://electronics-diy.com/stepper-motor-driver.php
http://websupport1.citytech.cuny.edu/Fa ... rcuits.htm
http://www.8051projects.net/stepper-mot ... ctions.php

[s.k.sahoo]

Dear Mr Enamul,

Thanks again for helping me in this project.
Actually i bought 2Nos old Stepper Motor from Bangalore this time.
These are manufactured by a Thailand based company "Minebea".
The type no is 23KM-K051-G2 having 6 connecting leads.
MINEBEA 23KM-K051-G2 axis length 22 mm dai 6.3 mm Torque 9.5 kgf-cm unipolar / bipolar 6 line.
Price: 450.00 Baht
Code: STP011.
Dimensions: W5.60 x L5.20 x H5.60 cm
Weight: 0.70 kg
These are the information i found in the internet. I don't know the Max or Min Current rating of this Motor.
I also bought a 24V 2A max Stepper controller from Bangalore, i am using 4leads of the motor to this controller
the speed is not smooth at low speed. I want to build my own.

Thanks
With best regards
sks

[Enamul]

Hi SKS,
I think the attached file is the spec of your motor...

[s.k.sahoo]

Thanks Mr Enamul,
Yes this is my Stepper Motor.

Thanks
With best regards
sks

[s.k.sahoo]

Dear Mr Enamul,

Good Morning.
I am not able to decide, whether i should go with ULN type drive or Transistor type drive.
I can pause the Solid State AVR Project for time being, but i have to take up this project in
urgent basis. Right now i need a sample PIC based schematics using Transistors to drive Stepper Motor
Your help is seriously needed.

Thanks
With best regards
sks

[Enamul]

Hi SKS,

Ok. You can start working with the attached schematic to see how your motor behaves in terms of accuracy in positioning.

[Enamul]

Hi

I have managed to find out push-pull drive..here it is..

[s.k.sahoo]

Dear Mr Enamul,

Good Evening, here is the basic schematic attached, please see and guide.
I don't want RS232 input ctrl right now, external switches for control the stepper will do,
by doing this i can understand better. after finishing this we car go for PC interface.

Thanks
With best regards
sks

[Enamul]

Hi SKS

I feel the same. Don't go for RS232 right now. We can start and see how we can control using external switch and then can move for PC based control. you can put two switches one for start/stop and other for direction control (CW/CCW). It's better to put switches as active low (i.e., PIC pins normally kept high by pull-up resistors and pulled down by switch).

[s.k.sahoo]

Dear Mr Enamul,

I have attached the revised schematics, please see and correct if any errors are there.

Thanks
With best wishes
sks

[Enamul]

That seems nice and ready to test

[s.k.sahoo]

Dear Mr Enamul,

Thanks for giving an OK signal.
I will purchase the components 2more, assembly in a breadboard then we can test.
So we have to wait for that time.
Are the values of the Resistors are OK?

Thanks
With best regards
sks

[Enamul]

Are the values of the Resistors are OK?

seems ok to me.

[s.k.sahoo]

Dear Mr Enamul,

Good Morning. I have revised the schematic a little. Please check and conform for assembly.
I have added 12v Zener diodes at Gates of MOSFETS, increase Drive supply to unregulated 12V
and shifted the control switches from PortC 0,1 to PortA 4,5 for easy connections.
Please see the attached Schematic and conform.

Thanks
With best regards
sks

[medelec35]

Hi sks,
Just thought I would mention that transistors will only pull-up each gate by 5.6/6.6x5-.7
=3.5V since npn is used as an emitter follower therefore emitter will be approx 0,7V lower than base voltage.

Not looked at the data sheet for your FET, but you need to make sure that fet gate turn on is above minimum turn on threshold voltage.

I'm not an expert in this field, so it's only my theory.
If you want a higher drive supply, then I can take a look when I get the chance.

Martin

[s.k.sahoo]

Hello Sir,
Goo Evening
Thanks for studying the schematics and guide me.
Please clarify a little on your calculation " 5.6/6.6x5-.7 =3.5V "
Do you mean to recalculate the values of my Resistor divider connected to
Transistor's Base?
The Push Pull Drive Supply is +12v.
Your reply will help me, so pl answer.

Thanks
With best regards
sks

[medelec35]

Hello Sir,
Please clarify a little on your calculation " 5.6/6.6x5-.7 =3.5V "

Sure. 5.6 = 5k6 resistor
6.6= 5k6+1k resistors
So its a ratio of a potential divider (or voltage divider) resistor network. in other words (5.6/6.6)x100 =84.8% of voltage is going to be across lower resistor (5k6),
5=5V supply
0.7= base emitter voltage drop since base is about 0.7 higher than emitter.
so splitting up formula
voltage across R6, R8 R10 and R12 when there is 5V at DRV of each divider=
5.6/6.6x5=4.24V
since there is 0.7V drop across base and emitter of NPN then voltage available going to Gate of each FET = 4.24-0.7 = 3.54

So it does not matter what supply you have going to FET there will onlt be 3.54V available.

Hope this helps, and hope I have got it right?


Martin

[Enamul]

Hi SKS
Martin has picked a very important issue but we can simply get rid of the problem of gate driving voltage by using opto-coulper after PIC to drive the push-pull circuit. I don't want to change push-pull circuit as that is recommended for high-frequency drive of MOSFET. Another issue is if you add opto-coupler like 4N35 for each coil drive it will protect PIC from any adversities that could happen due to motor coil drive.

Edit: Vgs(TH) for IRFZ44 is 2V (min) and 4V (max). It seems that Z44 should still drive OK. I have used that couple of years back..but recently used all with opto-coupler. In those case Vgs was close to 12V and works perfect..so as you are testing this in bread board first..you can test the circuit as it is.. if seems problem in driving you can add opto-coupler.

[s.k.sahoo]

Respected Sir,

Thanks for elaborating the calculation you made.
Your calculation is correct as per my knowledge. How could you be wrong?
I thinks 3.54v will be sufficient to drive the MOSFET, I will follow the data sheet
and decide the voltage divider value.
Is it K?

Thanks
With best regards
sks

[medelec35]

Is it K?

If you mean are resistances in K then yes.

I have only removed K since its less buttons to press on a calculator

Hower results will be the same in calculations if using ohms, K or Meg.

In practice on real hardware the only difference will be the current flow, and loading effects.

So best stick with Kohms.

Martin

[Enamul]

Hi Martin
I guess he meant "Is it OK" but missed O.
@SKS
You can use 1K for base drive and 10K for pull-down which will cause base voltage to be (5*10K/11K)=4.54V so gate voltage will be 4.54-0.7=3.85V

[s.k.sahoo]

Hello Mr Martin ,

Sorry for late reply, yes what Mr Enamul has guessed that is right. I meant " is it OK " but by mistake i missed "O".
Any way thanks for helping me.

Thanks
With best regards
sks

[s.k.sahoo]

Dear Mr Enamul,

Thanks for clarifying my typing mistake to Mr Martin.
Ok, i will change the 5K6 resistors to 10K, shall i reduce the value of Gate drive resistors from 1K to 100 ohms or less?
In schematic it is 1K. I will complete the assembly work tomorrow.

Thanks
With best regards
sks