Easy Stepper

From RepRapWiki
Jump to: navigation, search

Crystal Clear action run.png
Easy Stepper

Release status: Working

Easy Stepper Rev1 Front Small.jpg
Description Easy Stepper Rev1
License CC-BY-NC-SA
Author Kenneth Weiss
Contributors
Based-on Delta
Categories Stepper motor drivers, Tool, Tester, Toy, Electronics, surface-mount electronics
CAD Models
External Link Easy Stepper


Contents

This is a driver for your stepper driver.

SD2 Overview lille.jpg



Please note that the Easy Stepper does not come with a stepper driver or stepper motor included.
It’s both a stepper motor tester and a stepper driver tester.
It’s also a tool for when you are making any kind of device that includes stepper motors or a toy to play with the stepper motor parts that you scavenged from some old equipment.

The Idea

The idea is to make a quick and simple tool to test stepper motors and mechanical assemblies such as stepper driven gearboxes and linear activators.
Just hook up whatever power supply (between 8 and 24V, AC or DC) you have lying around to the screw terminals or the barrel jack connector and whatever stepper driven device you have to the motor out pin header or screw terminal and you are ready to go.

The Motivation

The reason for this project was my frustration over how much it takes to just test a simple stepper motor.
To test a stepper motor you usually need some kind of MCU most likely a Arduino, your breadboard, cables, some kind of driver and other components.
When you got all that assembled you still need to write and upload some code to run the driver, but before you can do that you also need to find your USB cable and if the code doesn't work you have to debug it.
All this can easily take an hour but with the Easy Stepper you just plug in your stepper motor and whatever power supply you have and you are ready to go.

How to Connect

First of a disclaimer:
There are many how to guides and blogs out there that tell you exactly what wire color connects to what in the stepper motor and to your stepper driver.
But there is no international standard regarding wire coloring for stepper motors so the wire coloring it's up to what the individual stepper motor manufacture fell like.
This means that that the color combination on a stepper motor from one manufacture does not necessarily match the color combination on a stepper motor from another manufacture.
For that reason we have chosen not to use colors in this description.


ES Bi 4P.png

The Bi-polar stepper motor is the most commonly used stepper motor these days and the easiest type to connect to the Easy Stepper.
The Bi-polar stepper motor consists of two coils (Phase A and B)


ES Uni 5P.png

The middle of the two coils inside a 5 wire Uni-polar stepper motor is internally connected and brought out in a single wire as the 5th wire. (C1+2)
There is to our knowledge no 5 wire uni-polar stepper motor driver that's compatible with the Easy Stepper, so don't attempt to connect a 5 wire uni-polar stepper motor to the Easy Stepper as you might damage the stepper motor driver that you ar using.


ES Uni 6P.png

The 6 wire Uni-polar stepper motor differs from the 5 wire Uni-polar stepper motor in that the middle of the two coils are not internally connected but instead brought out as two individual wires (C1 and C2)
If you cut off or just isolate the ends of these two wires and leave them be you can connect the remaining 4 wires from the 6 wire stepper motor as if it was a 4 wire Bi-polar stepper motor.


ES Uni 8P S.png

With the 8 wire Uni-polar stepper motor things start to get complicated and there are different ways that they can be constructed but here are two examples.
We recommend that you connect the 4 coils two by two in series and thereby turning it into a 4 wire Bi-poler.


ES Uni 8P P.png

You can also connect the 4 coils two by two in parallel and thereby decrease the coil inductance, which can lead to increased performance if you have the ability to deliver more current.
However, most stepper motor drivers actively limit the output current per phase and you will only get half the phase current flowing through each of the two parallel coils.

The Controls

The controls are really simple.

When the potentiometer is centered the stepper motor will stand still.

When the potentiometer is turned clockwise the stepper motor will start turning in one direction.

The further you turn the potentiometer the faster the motor turns and when you turn the potentiometer back the stepper will slow down again.

When you turn the potentiometer counterclockwise past the center the stepper motor will start turning in the other direction.

The two buttons are for fast forward and fast backwards.

With the MS1-2-3 jumpers you can set the microstep resolution on the Polulu/Stepstick.

The Use-Enable solder jumper should not be used with the standard firmware.

Data

Input: 8 to 24V AC/DC

Output: Depending on the Pololu/Stepstick and power supply you are using.

Size: 40X60mm

MCU: Attiny10-TSHR - 8BIT - 12MHZ

Source code: File:EasyStepper v1.zip

Pololu/Stepstick compatibility

The Easy stepper is compatible with most pololu/Stepstick's

There are many different versions of stepper drivers and it's important to orient the stepper driver correctly in the Easy Stepper, so make sure to check how to orient the one you are using.
Here are some examples.


Easystepper orientation.jpg



Some newer stepper drivers like the RAPS 128, with 1/128 microstep, does not have an inverted input signal on the Enable pin. This means that the Enable pin needs to get pulled up to 5V instead of down to GND for the stepper driver to work.
This can be done by making a connection directly from 5V to the Enable pin on either the Easy Stepper or the stepper driver itself.
Doing it on the Easy Stepper will make it incompatible with regular stepper drivers (until changed back) so I recommend doing it on the stepper driver instead.


RAPS 128 fix.jpg

Reprogramming the firmware

You can reprogram the Easy Stepper through the programming port on the backside of the Easy stepper.
The Easy Stepper isn't based on the regular Atmel ISP setup, but it's based on the Atmel TPI Programming Interface, you can find more info here: [http://www.atmel.com/Images/doc8373.pdf Atmel Tiny Programming Interface (TPI)]

To program the Easy stepper I use the AVRISP mkII programmer: AVRISP mkII

There is also other ways to program the ATtiny.
Take a look at this Hackaday post to see how it can be done.

Where to get it

Easy Stepper at RepRap.me

Development history

PCB Outline

The PCB outline is based on the Sick of Beige PCB from Dangerous Prototypes but the size that I wanted wasen't in the library so I made my own version of the library with a 10mm increment all the way from 20X20mm to 150X150mm with both unplated and plated mounting holes.

PowerExpander All sizes small.png


Download the Eagle library here: <{ File:Dp pcb-All sizes.zip }>

Easy Stepper PCB.png

Rev1

Easy Stepper Rev1 Front Small.jpg Easy Stepper Rev1 Back Small.jpg

File:Easy Stepper Motor Control.sch.pdf

3rd prototype

So I found out the hard way that if you plug in the stepstick the wrong way you will Zapp the stepstick and the ATtiny10 on the Easy Stepper.

I don't think that there is any way to protect the stepstick/pololu but I am currently working on a way to protect the Easy Stepper.

2nd prototype

ES prototype2 small.jpg ES prototype2 back small.jpg

1st prototype

ES prototype1 small.jpg ES prototype1 back small.jpg


The PCB for the 1st prototype is made on the LPKF Protomat C60 PCB milling machine in Labitat.