We ordered a 3M prototype socket for the Allegro stepper motor controller 24 pin SOIC package and constructed a test board with wires for each pin. This assembly is seen in the lower left of the image. Parameters are set as: slow-decay mode (PFD high); full-step (MS1 &MS2 low); Rt=56K & Ct=680pf; Vref=4v; Rs=1.25ohm.
Validating the design, I measured V sense resistor=.32V and I motor supply=300ma which matches the design figures closely. Also, the square wave on both sides of the motor indicates the pwm is working. I tied the STEP input high with a pull up resistor. I have a 555 timer running at a very low frequency sucessfully driving the STEP input resulting in discrete rotation. Our objective is to use a stepper motor to control a claw on the ROV for grasping objects underwater. We are gathering a fine collection of stepper motors from old printers cast off at the local recycling station.
Note the black power supply (0-17vdc) at top that David built recently for our lab projects.
