and I want to control them with one arduino (and, if needed, an external board for 12V-power; but which one?). I cannot change the motor types, since they're builtin in a very complex piece of hardware I acquired and they're "hardwired" everywhere.
Through trial-and-error I already found out that switching ground and power (from the 5V-port of my arduino uno), I can control the direction (this works, but doesn't have enough power, since they're 12V-motors). This is also needed, so I'd need a way of "changing" the direction of the current.
I'm a software engineer and I feel comfortable with coding the software needed for this, but I have no clue about hardware. So, my questions are:
What kinds of extra-boards do I need?
Is there a module implementing the direction switch without me manually assembling that? (I already found this: editor_embed circuit StackExchange 2014-04-19 20:09:52.967713 - CircuitLab , but the space in my device is very restricted, so this circuit might be too much if build with the standard arduino devices; a single chip would be nice for this).
How to connect the extra-boards I need together so that I can use 12V (from an external source)?
It's important that this is all on one board, since all of the parts need to work together very exactly, there's little room for faults.
Interestingly, this thread is the second Google result for BOTH of those part numbers. To save us a little Googling, what do you already know about the parts? Have you found a "datasheet" yet? If you do, link it in your post. (Use the full editor to get the link button.)
The important specification on the motors is the stall current. Sometimes called starting current. That's the peak current that the motor driver chip has to handle. If the peak is under 3A (even better, under 1.2A) then something like the TB6612 is a good chip to drive the motor in both directions. You can get a TB6612 breakout from Adafruit to experiment with the chip on a breadboard.*
Single-chip solutions go up to about 30A, so it is likely that you can fit one of those into your design.
*Please ignore the stepper motor shown in Adafruit's photos. This chip really isn't suitable for most steppers.