Data Sheet

current through the other coil is zero.

The Tic’s speed, velocity, acceleration, and deceleration numbers are all denominated in

microsteps, which are also called pulses. Therefore, if you change the step mode, you

might have to change those other settings to account for the change. For example, the

default maximum speed for the Tic is 200 pulses per second. If you change the step

mode from full step to half step, you would have to change the speed to 400 pulses per

second to maintain the same angular rate of change. Since the step mode affects those

other parameters, it is a good idea to set it first.

Setting the decay mode

The Tic has a decay mode setting that affects how fast current through the motor coils decays during

each step. The Tic T825 has three decay modes: slow, mixed (default), and fast. The Tic T834

has five decay modes: slow, mixed 25%, mixed 50% (default), mixed 75%, and fast. The decay

mode matters most when microstepping is used. Which decay mode is most appropriate depends

on many factors specific to a particular stepper motor system, including the motor’s resistance and

inductance, the supplied motor voltage, and the desired speed. Generally, using slow decay generates

less electrical and audible noise, but it can result in missed microsteps when the coil current is

decreasing. Fast decay is much noisier both electrically and audibly, but it creates more evenly

sized microsteps. Mixed decay is a combination of both fast and slow decay that tries to minimize

noise while keeping microsteps as even as possible. For more information about the decay modes

and current control methods of the Tic’s stepper motor driver, refer to the DRV8825 datasheet

[https://www.pololu.com/file/download/drv8825.pdf?file_id=0J590] (1MB pdf) for the Tic T825 or the DRV8834

datasheet [https://www.pololu.com/file/download/drv8834.pdf?file_id=0J617] (2MB pdf) for the Tic T834.

Setting the movement parameters

After you have set the motor’s step mode, current limit, and decay mode, you should set its maximum

speed and maximum acceleration.

The Tic represents speeds (non-negative values indicating the magnitude of a velocity), velocities

(signed values indicating speed and direction), and speed limits in units of pulses (microsteps) per

10,000 (ten thousand) seconds. The Tic can send up to 50,000 pulses (microsteps) per second, so

the maximum allowed speed setting is 500,000,000. However, your motor might not be capable of

moving that fast. If you want to get the maximum speed possible out of your motor, you might have to

do some tests to see how fast it can go. To do this, set the max speed to 500,000,000 in the “Input and

motor settings” and click “Apply settings”. Then go to the “Set target” box in the “Status” tab, select

“Set velocity”, and enter smaller numbers in the boxes at the ends of the scroll bar that determine its

range. For example, try entering -4,000,000 and 4,000,000, which would mean the scrollbar can set

target velocities between −400 pulses per second and +400 pulses per second, as shown below.

4. Setting up the controller Page 29 of 150