Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: vbsaltydog on August 21, 2011, 05:45:58 AM

Title: Microcontroller and stepper motor help needed
Post by: vbsaltydog on August 21, 2011, 05:45:58 AM
I am a computer programmer with nearly zero knowledge of electrical circuits but I have a small robotic device that I want to build so I am looking for some help.

I want to take a picaxe microcontroller and program it to change the position of a stepper motor three times per day.

I understand the picaxe programming part but I do not have the knowledge to wire the picaxe and stepper motor to the breadboard.

The stepper motor needs to turn a small knob with < 5 Lbs of torque.

Any help is appreciated.
Title: Re: Microcontroller and stepper motor help needed
Post by: waltr on August 21, 2011, 08:38:59 AM
Quote
< 5 Lbs of torque.
Do you mean 5 Ft-Lbs or 5 in-Lbs of torque? (read about Torque in Wikipedia)

Does the stepper motor have a gear reducer on it? Gear reduction decreases the output speed of the shaft but increases the output torque.

Is the stepper a Bi-polar or uni-polar coil arrangement? This determines which drive circuit you can use.

Can you post a link to the stepper motor data sheet?
Else, what is the stepper's Voltage and current requirements?

Typically, there would be a driver circuit between the processor and the stepper. A processor's output pins can only deliver a small current (typ. <20mA) and motors draw much larger currents (can be many Amps). Google "stepper motor driver" to find more info.

A place to find some info is in Microchip's App Notes and docs. They has several about using stepper motors and these are free downloads from their web site. These can help you learn how to interface a stepper to a PIC.
Title: Re: Microcontroller and stepper motor help needed
Post by: vbsaltydog on August 21, 2011, 08:49:20 AM
Thank you but I read several docs about microcontrollers interfacing with stepper motors after posting here and I am out of my depth in electronics so this project is on hold until I can consult with a electronics person that will build the board. Then I will handle the programming logic.

Thanks again for the info.