Easy Stepper
Release status: Working
Description | Easy Stepper Rev1
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This is a driver for your stepper driver.
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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.
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)
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.
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.
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.
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.
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.
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
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.
Download the Eagle library here: <{ File:Dp pcb-All sizes.zip }>
Rev1
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
1st prototype
The PCB for the 1st prototype is made on the LPKF Protomat C60 PCB milling machine in Labitat.