Stepper motor driver


Hiya all,

I am a beginner and have a large RC Crane project on my desk. I have the idea of how I want to achieve the mechanisation of the telescopic boom.
it involves 3 sets of stepper motors
1_ 2 x micro steppers ; to control the retraction of a locking pin, the motors work simultaneously in parallel
2_ 2 x micro steppers ; to control locking pins to pick up the boom section, the motors work simultaneously in parallel
3_ 1 x nema 8 ; to control the carrier that hitches to the boom section and moves it.

I need to select hardware to control these motors. I have a big easy driver but for some reason I can’t get it to work. the motors work when connected directly to my mega board but not to the driver. (sparkfun).

I would like it to be a simple set up. there is only one endstop which is for the nema 8.

I intend to control the motors based on distance to travel.

The RC component I intend to build too. idea is to use a touch screen interface to select boom sections and the location I want them to travel to.

any hardware suggestions for the drivers?

many thanks



A quick look at the bigeasy says it should be easy to use. When you say “doesn’t work” that does that mean? Nothing at all happens with the motors? I’d check the state of the enable and sleep pins. If enable is high the fets are off and nothing will happen, if sleep is low same thing (fets are off, motor does nothing). If you post the Fritzing sketch of your hook up I expect one of us would point out any problems we see.

Edit: reading further down the data on the board there is also a current limiting pot, if that is set to less current than your motor needs to operate that would also cause no operation very likely.

edit2: I got this information from the Sparkfun hookup guide available here

which may help you out. Generally Sparkfun has excellent tutorials (and often Fritzing parts) for their stuff.



did put the meter on the enable pin and it did register voltage so I assume it’s high.
check: meter neg on gnd and pos on pin.

I used the example sketch which compiled and uploaded fine. I’ll have another look at it. am sure it should work but not sure why it isn’t.

still quite new to this so will try tonight.



As you likely don’t need the enable or sleep pins I’d put a wire from the enable pin to ground (to make sure its low) or connect it to a Arduino output pin and set that low (but not both as that may damage the Arduino) and connect sleep to +5V with a 1K ohm resistor to make sure it is high. If it still doesn’t work you could check the voltages on the motor connections. If it isn’t stepping they should be stable and should be either ground (or close to it) or the motor supply voltage (possibly 12V?), if it is less than the supply voltage you are probably looking at current limiting and need to first check the wiring to make sure you don’t have a short and then increase the current limiting pot as the tutorial indicates until the driver is supplying enough current to run the motor.




thank you will do that. just a quick question regarding the sketch on the example. how much of it do I need? all of the sketch pieces or first plus one of the others?




With a quick look at the code, I’d probably use the entire sketch so everything works as they expect it to as that should work under any conditions. If you don’t want the microstep functions you could omit that part of the sketch and modify the if statements to not execute the omitted parts, but if you are new to coding it may be easiest to start with the whole sketch and once that works (so you know everything is ok) then change the code and see what breaks (which can range from no longer compiling correctly to compiling but working oddly or part not working). The usual reason (other than being sensibly lazy and not wanting to type too much code in :slight_smile: ) to omit code would be because the sketch is too large to fit your processor but that isn’t likely to be the case here if this is the only thing running. I prefer to start from something I know works (so both the hardware and the software are known to be fine) and then make changes from there.