power supply for 3 stepper motors

by brawo on Sat Nov 17, 2012 4:46 am

Hi,

i would like to power 3 stepper motors and at the same time have current sensors.

In my intended circuit, i have 2 stepper motors (ratings: 5V, 0.57A/phase) connected to an INA219 high side current sensor which is then connected to the motorshield

i also have another stepper motor (ratings: 5.6V 0.67A/phase) that is connected to an A4988 motor driver and then connected to the motor shield

1) does the A4988 motor driver have its own in built current sensor? if it doesn't then is it possible to connect an INA219 current sensor to it? or is there an easier way?
2) what is the best way to power such a circuit? i was intending of having 3 external power sources that would power each stepper motor but i read on the forums and i could use the arduino supply but i must remove the power jumper? (i'm not too sure about this)
brawo
 
Posts: 13
Joined: Tue Nov 13, 2012 3:59 am

Re: power supply for 3 stepper motors

by adafruit_support_bill on Sat Nov 17, 2012 5:44 am

In my intended circuit, i have 2 stepper motors (ratings: 5V, 0.57A/phase) connected to an INA219 high side current sensor which is then connected to the motorshield

The sensor would need to be connected to the controller (shield), not the motor. It would go between the positive terminal of the external power terminal and the high side of your power supply.
does the A4988 motor driver have its own in built current sensor?

I don't have any experience with that controller. As I understand it, it has adjustable current limiting, but I don't know if you can read back the actual current. Your supplier for the controller should be able to answer that question for you.
it possible to connect an INA219 current sensor to it?

You should be able to connect the INA219 between VMOT and the high side of your power supply.
what is the best way to power such a circuit? i was intending of having 3 external power sources that would power each stepper motor but i read on the forums and i could use the arduino supply but i must remove the power jumper?

You can use one source for all your motors, but it is generally better to use a different supply for the Arduino.
User avatar
adafruit_support_bill
 
Posts: 25526
Joined: Sat Feb 07, 2009 9:11 am

Re: power supply for 3 stepper motors

by brawo on Sat Nov 17, 2012 6:48 am

hi,

ok uhh i've attached a schematic of my circuit. i used fritzing to model it. could you tell me which part of it is wrong. assume the batteries are external power sources haha thanks thanks.

i'm not exactly sure whether what i've done is right. thank you for your advice
Attachments
circuit.png
circuit.png (443.79 KiB) Viewed 670 times
brawo
 
Posts: 13
Joined: Tue Nov 13, 2012 3:59 am

Re: power supply for 3 stepper motors

by brawo on Sat Nov 17, 2012 6:51 am

ohhh could you assume that the board in the middle is the adafruit motor shield. lol i couldn't find the fritzing file for it.

oh could you explain the EXT_PWR slot on the motor shield. what could i use it for?
brawo
 
Posts: 13
Joined: Tue Nov 13, 2012 3:59 am

Re: power supply for 3 stepper motors

by adafruit_support_bill on Sun Nov 18, 2012 11:28 am

A couple of problems there:
assume the batteries are external power sources

You don't connect the power source directly to the motor. It has to connect to the shield of you want the shield to be able to control the motor. See here for how to connect an external supply: viewtopic.php?f=31&t=26873

Also, you are using bipolar stepper motors (4-wire). The current on each coil reverses every-other step. If you short the two coils together as in your diagram, the motor cannot run.

And, as I stated in my previous post:
The sensor would need to be connected to the controller (shield), not the motor. It would go between the positive terminal of the external power terminal and the high side of your power supply.
User avatar
adafruit_support_bill
 
Posts: 25526
Joined: Sat Feb 07, 2009 9:11 am