Laser Cutter Build Night: Cables and Logic Voltage

In tonight's session, I built and connected up some cables for the motor-EasyDriver interface and for the EasyDriver-Raspberry Pi interface.  I found some really great 4-pin female connectors from the rear projection TV mentioned in the last build night's post and stripped these for the motor connections to the EasyDriver.  To identify which coil was which with the stepper motors, I spun it manually without any wires connected.  Then, I methodically shorted two of the motor's wires until I felt a great resistance while trying to turn the shaft.  These wires that make the motor harder to turn are one coil, and the other two are another coil.  I found some great info on the RepRap wiki, so check it out!  They say that polarity and order of coils don't matter on the 4-pin connector, as long as each coil's pair of wires are on their own end of the connector.  For example, on the connector, they might go like:

Coil_1A  Coil_1B  Coil_2A  Coil_2B

but the couldn't go like:

Coil_1A  Coil_2B Coil_2A  Coil_1B

because the leads for the coils aren't together.  If I wish to change the direction the stepper spins in, I can just flip the 4-pin connector 180°.  Below (right) is the finished motor connection layout:

On the left are the cables to go from the EasyDriver GND-STEP-DIRECTION header to the Raspberry Pi.  They are simple 3-pin connectors soldered to three solid-core breadboard-size wires for easy insertion into a breadboard.  They will ultimately be soldered to all the other necessary components. 

Lastly, I discovered that I need to set the EasyDrivers to accept 3.3V logic signals from the Raspberry Pi instead of their default, 5V.  To set this, I simply placed a dab of solder over the solder bridge SJ2 (bottom left on boards):

I would rate the build night "highly successful."  I am excited to finish the electronics tomorrow night as well as getting the Raspberry Pi up and running with code!