NuSTEPPER

Description: The NuStepper is a circuit designed by Wilf Rigter, utilizing a 74AC86 quad XOR chip to create four neural neurons configured in a ring. This circuit operates similarly to a microcore and can drive a bipolar stepper motor. The NuCore, previously described, has been renamed the NuRING. Like the Nv Microcore, the NuRING consists of multiple process nodes connected in a ring configuration. Each node features a single capacitor and resistor with a gain stage, functioning as an integrator rather than a differentiator, which is akin to a "relaxed" neuron. Linear devices such as AC240 or AC245 serve effectively as gain elements for multi-node NuRING circuits. As long as the sign of all inversions in the NuRING remains negative, it can be constructed from various combinations of inverting and non-inverting elements. The process pattern in linear NuRINGs is robust, similar to that of Schmitt trigger NuRINGs, with a voltage swing at the Nu bias point of NuRING S exceeding 2 Nu, approaching rail-to-rail levels. The Nv Microcore circuit was previously utilized to generate a "wave" step sequence for both unipolar and bipolar stepper motors. It was observed that the NuRING Grey Code "phase" and "phase to phase" output patterns correspond to 1/2 step sequences for both motor types. Testing was conducted with a small bipolar stepper motor typically used for head positioning in a 3.5-inch floppy disk drive. To drive steppers using Nv Core circuits, output buffering is necessary for feedback isolation, as the nervous neuron is susceptible to motor transients, which can induce process modulation, instability, and saturation if motor windings are directly connected to a Nv Core. In contrast, the NuRING offers excellent noise immunity, allowing its outputs to be directly connected to stepper motors, as any motor transients are integrated at the bias point. When either the REV or FWD input is low, the stepper motor rotates in that direction. With a resistor value of 510K and a capacitor value of 0.01, the speed reaches 4 revolutions per second, with a power consumption of 40 mA. When both inputs are high or low, the stepper motor halts, and the current drops to zero. Although the torque is relatively low, it is suitable for lead screw applications of the floppy disk drive stepper motor. The four boxes in the lower right corner (Yl / Bk / Or / Bn) represent the pins on a typical stepper motor plug, corresponding to the colors of the stepper motor's wires.

The NuStepper circuit is an innovative solution for driving bipolar stepper motors, leveraging the capabilities of a quad XOR chip to create a network of neural neurons. The design's ring configuration allows for efficient signal processing, enabling the generation of precise control signals necessary for stepper motor operation. The integration of capacitors and resistors at each node facilitates the creation of a smooth and stable output, crucial for maintaining motor performance.

In practical applications, the circuit's ability to manage motor transients through integrated feedback isolation is a significant advantage. This feature ensures that the sensitive neuron components are protected from potential disturbances caused by the motor's inductive loads, which can lead to erratic behavior if not properly managed. The integration at the bias point allows for a stable operation, ensuring that the stepper motor's performance remains consistent even under varying load conditions.

The output characteristics of the NuRING circuit are particularly noteworthy. The ability to produce Grey Code output patterns simplifies the control of stepper motors, allowing for half-stepping modes that enhance resolution and control. This capability is especially beneficial in applications requiring precise positioning, such as in robotics or CNC machinery.

Moreover, the NuStepper's power consumption and operational speed make it an efficient choice for applications where energy efficiency is paramount. The design's capability to operate at 4 revolutions per second while consuming only 40 mA exemplifies its suitability for battery-powered or low-power applications.

The connection of the stepper motor to the NuRING outputs is straightforward, with clear pin assignments indicated by the color-coded boxes. This user-friendly design aspect reduces the complexity of integration, allowing for quicker assembly and deployment in various projects.

Overall, the NuStepper circuit represents a sophisticated approach to stepper motor control, combining innovative design principles with practical application considerations, making it a valuable tool for engineers and hobbyists alike.The following is a copy of an article posted by Wilf Rigter to the original BEAM email list and as such represent an important historical and technical reference The NuStepper is a circuit designed by Wilf Rigter, using a 74AC86 quad X-OR chip to make four Neural Neurons configured in a ring. The circuit behaves much like a microcore and can be used to drive a bipolar stepper motor The NuCore was described in my earlier post and has now been renamed as the NuRING. Like the Nv Microcore, the NuRING is made from a number (ie 4) of process nodes connected in a ring. It uses a single capacitor and resistor with a gain stage for each node but as an integrator instead of a differentiator.

Think of it as a "relaxed" neuron ! First of all, any linear devices like AC240 or AC245 work well as gain elements for (>1 Nu ) NuRING circuits. As long as the sign of all inversions in the NuRING is negative, it can made from any combination of inverting or non inverting elements.

The process pattern in linear NuRINGs is just as robust as the Schmitt trigger NuRING S and the voltage swing at the Nu bias point of NuRING S >2 Nu approaches rail to rail. I had previously used the Nv Microcore circuit to generate a "wave" step sequence for unipolar and bipolar type stepper motors and I realized that the NuRING Grey Code " phase " and " phase to phase " output patterns were identical to 1/2 step sequences for both types of stepper motors.

I tested this idea with a small bipolar stepper motor of the type used for head positioning in a 3. 5 inch FD. In order to use Nv Core circuits to drive steppers, you must use output buffering for feedback isolation because the Nervous neuron is sensitive to motor transients which in large quantities could cause process modulation, instability and saturation if motor windings were connected directly to a Nv Core. However the Nu offers exquisite noise immunity and NuRING outputs can be directly connected to stepper motors since any motor transients are integrated at the bias point.

When either REV or FWD is low the stepper rotates in that direction. With the component R=510K and C=0. 01 the speed is 4 revolutions per second and power consumption 40 mA. When both inputs are high or low the stepper is stopped and the current is zero. While torque is quite low it`s useful for the lead screw application of the FD stepper motor. The four boxes in the lower right corner (Yl / Bk / Or / Bn) represent the pins on a typical stepper motor plug, and the corresponding colors of the stepper motor `s wires.