Hi.
Yes, the Tic T825 can be used to drive a stepper motor at a constant speed. The best way to do it might depend on your setup, but a simple way would be to put the Tic in analog speed control mode, set the maximum speed to whatever value corresponds to 15RPM with your motor and microstepping mode, and then connect a high (5V) signal to the analog input pin (SDA/AN). The speed on the Tic is in units of microsteps (or pulses) per 10,000 seconds. More details about configuring a Tic T825 can be found in its user’s guide.
-Claire