4.2. Connecting the stepper motor and power supply

The information in this section can help you connect your stepper motor and power supply to the Tic.

To avoid damage or injury, please read these safety warnings carefully:

Warning: This product is not designed to or certified for any particular high-voltage safety standard. Working with voltages above 30 V can be extremely dangerous and should only be attempted by qualified individuals with appropriate equipment and protective gear.

Warning: Connecting or disconnecting a stepper motor while the Tic’s motor power supply (VIN) is powered can destroy the motor driver. (More generally, rewiring anything while it is powered is asking for trouble.)

Warning: This product can get hot enough to burn you long before the chips overheat. Take care when handling this product and other components connected to it.

Before connecting anything to the Tic, we recommend running the Tic Control Center software to make sure it can connect to the Tic over USB. This way you can ensure that the Tic is functioning before you spend time soldering connectors or connecting other electronics, and if something goes wrong, you will have a better idea of what caused the problem.

Connecting a bipolar stepper motor with four or six leads

Bipolar stepper motors commonly have four or six leads. These two-phase stepper motors have one coil per phase, with one lead connected to each end of each coil. Versions with six leads also provide access to the centers of the two coils so that the motor can optionally be controlled by a unipolar driver. When controlling a six-lead stepper motor with a bipolar driver like the Tic, only the ends of the coils are used, and the two center tap leads should be left disconnected.

Connecting a two-phase bipolar stepper motor with four (4) leads to the Tic.

Connecting a two-phase unipolar/bipolar stepper motor with six (6) leads to the Tic. The two center taps are left disconnected.

Swapping A1 with A2 or B1 with B2 in the above diagrams just reverses the direction of the motor. Swapping both will leave the direction unchanged.

Connecting a bipolar stepper motor with eight leads

Unlike four- and six-lead stepper motors, which have a single coil per phase, eight-lead unipolar/bipolar stepper motor have two coils per phase and give you access to all of the coil leads. You have the option of using the two coils for each phase in parallel or in series.

When using them in parallel, you decrease coil inductance, which can lead to increased performance if you have the ability to deliver more current. However, since the Tic actively limits the output current per phase, you will only get half the phase current flowing through each of the two parallel coils. When using the phase coils in series, it’s like having a single coil per phase (like the motor types discussed above). We generally recommend using a series connection. The following diagram shows how to connect such a stepper motor to the Tic with each pair of phase coils in parallel (left) or series (right):

Connecting a two-phase unipolar/bipolar stepper motor with eight (8) leads to the Tic with the phase coils in parallel.

Connecting a two-phase unipolar/bipolar stepper motor with eight (8) leads to the Tic with the phase coils in series.

Power supply

To connect your power supply to the Tic, connect the negative or ground terminal of your power supply to the Tic’s GND pin on the high current side of the board (next to motor output A1). Then, connect your power supply’s positive terminal to the VIN pin next to that.