Stepper Motor

There are many 9V chaser circuits that seem to waste about 7V when driving LEDs that are only about 2V. This project is unique, because it uses only two inexpensive alkaline battery cells totaling 3V for power. Since most of the waste is eliminated, the cells last a long time. Unlike the other circuits, this one flashes the LEDs for only about 30ms each, further extending the battery life. For user convenience, it has a stepper speed control and a brightness control. At slower speeds and with reduced brightness, the battery life is further extended considerably. Mounted in a circle, the LEDs appear to rotate as they step from one to the next.

M1 is a stepper taken from an old disk drive. There are five pins, i.e., common, coil 1, 2, 3 and 4. Resistance measured between common pin and each coil is about 75 Ohms. Driving current for each coil is then needed about 60mA at +5V supply. A darlington transistor array, ULN2003 is used to increase driving capacity of the 2051 chip. Each output provides 500mA max at 50V. P1.4 to P1.7, four output pins are connected to the input of the ULN2003 as shown in the circuit. Four 4.7k resistors help the 2051 to provide more sourcing current from the +5V supply. The serial port is optional for your exercises. Many have provided useful technical, and application of using stepper, see the links below.

This controller is designed to control (3) three unipolar stepper motors at up to 35V@1.25A continuous. The controller is optimized for use with shareware CAD/CAM software (i.e. DANCAD3D). Connections are provided for limit and home switches. Motor, switch, and power connections are via terminal blocks. Control inputs from the PC parallel port are via pads on the PCB. Logic power for the stepper control ICs and control input pull-ups is provided from the motor supply via a 7805 regulator. This should be safely usable at motor voltages up to 25V.

The 74AC240 stepper driver works by alternately enabling each half of the buffer. Only one half can be enabled at a time. Let's assume that the top half of the driver is enabled. U1A & U1B along with R8, C1, and the input protection resistor R7 form a square wave oscillator. The outputs of U1A & U1B directly drive one coil of a bipolar stepper motor.

When I build up this card, the 74*86 IC is "socketed," both to protect the IC during soldering, and to allow for experimentation with IC subfamily. Similarly, the timing resistors and timing capacitors are plugged into individual sockets to allow for tinkering with circuit timing (i.e., motor rotation speed).

You can, though, use this circuit to drive any bipolar or unipolar (via bipolar drive) stepper motor. In the Solarbotics diagram, the Yellow and Blue leads are the end contacts of one motor winding, and the Red and White leads are the end contacts of the other motor winding. In the case of the unipolar motor that Solarbotics sold, an additional two Green leads were the two windings' center taps, and left unconnected.

On these pages, I will introduce a control circuit for stepper motor. The software of this project is adapted to Embedded Systems(Lab13) for 2002 of Cleveland State University.

One of my student has made a disgraceful robot that used two stepper motors and with a simple IR sensor. Yes, above picture is what I'm talking. Without battery carrying, a little bit torque of the stepper and misalignment of driving shaft, makes it crawling not walking, but first demo, showed quite impressive to me. He said he wrote a couple of program lines using C, his robot can track the black tape. I feel delighted his intention and endeavor. I thought, " he borrowed me DS5000, expensive one, a soft uController with internal bootloader, why shouldn't try with our learning board C-52 Evaluation Board instead".

So he always stays on course, Jared designed a mechatronic device that simulates perfect steering in an automobile. The small-scale, single-wheel model determines the speed of wheel rotation from the magnitude of the curve it's traveling. It works by setting the initial speed of a PIC-controlled dc motor, then uses a manual-input turn radius to vary the speed of the motor and advance a PIC-controlled stepper motor one visible step (7.5 deg) in the specified direction.

As you can see this is a fairly complex formula, but with a little bit of work and some math it is possible to compute with the Stamp. Figure 1 shows the non-linear relationship of pressure vs. altitude. As you can see on the graph as pressure decreases, altitude increases, but the higher the altitude gets the less pressure changes. In other words the higher the altitude gets the stepper the slope of the curve gets. That is what gives the curve its non-linearity.

This is a voltage controller oscillator that was designed as a wide range oscillator to generate clock pulses for a stepper motor drive system. It does however have some interesting features. The original application used a stepper motor for its ability to operate over a very wide speed range, so this oscillator is also designed for a very wide frequency range.

This is an image Schematic. No Description available.

Typical stepper-motor control circuits use either logic gates and flip-flops or shift registers to generate the proper sequences of binary codes that produce bidirectional stepper-motor movement. A conventional stepper-motor-control circuit uses a square-wave generator, a sequence generator, or a shift register and current translators to control one stepper motor apart from the logic circuit necessary for producing a known and valid binary code at start-up.

You can, though, use this circuit to drive any bipolar or unipolar (via bipolar drive) stepper motor. In the Solarbotics diagram, the Yellow and Blue leads are the end contacts of one motor winding, and the Red and White leads are the end contacts of the other motor winding. In the case of the unipolar motor that Solarbotics sold, an additional two Green leads were the two windings' center taps, and left unconnected.

This application note will describe how to drive a bipolar stepping motor with the PIC16F684. The PIC16F684 has an ideal set of peripherals for driving a stepper motor. These peripherals include two on-chip comparators and an Enhanced Capture Compare PWM (ECCP) module. The ECCP module is used to microstep the motor while the on-chip comparators limit the current in the windings of the motor.

Stepping motors fill a unique niche in the motor control world. These motors are commonly used in measurement and control applications. Sample applications include ink jet printers, CNC machines and volumetric pumps. Several features common to all stepper motors make them ideally suited for these types of applications.

The 74AC240 stepper driver works by alternately enabling each half of the buffer. Only one half can be enabled at a time. Let's assume that the top half of the driver is enabled. U1A & U1B along with R8, C1, and the input protection resistor R7 form a square wave oscillator. The outputs of U1A & U1B directly drive one coil of a bipolar stepper motor.

The design in Figure 1 allows full direction and step control of a 12V, four-phase stepper motor from a 5V, TTL/CMOS-compatible logic controller. The circuit uses a Philips SAA 1027 control IC to generate the correct step sequences from the count input. The IC also has a reset function that allows you to temporarily stop the motor and reset the count and a mode control that specifies direction. The TIL199 optoisolator isolates the control signals.

The circuit in Figure 1 provides slewing control for stepper motors that you use in sophisticated applications, such as monochromator movements in optical experiments. The LM331 VFC plays a vital role in this circuit. The constant 10V dc from the IC9596 voltage reference routes to the VFC through the DG303 CMOS switch. The DG303's configuration is such that the VFC initially receives 0V through the grounded 33-kilohms resistor.

Stepper motors are useful in many consumer, industrial, and military applications. Some, such as personal-transportation systems, require precise speed control. Stepper-motor controllers can be simple (Figure 1), but they require a variable-frequency square wave for the clock input. The AD9833 low-power DDS (direct-digital-synthesis) IC with an on-chip, 10-bit DAC is ideal for this task, because you need no external components for setting the clock frequency (Figure 2). The device contains a 28-bit accumulator, which allows it to generate signals with 0.1-Hz resolution when you operate it with a 25-MHz MCLK (master clock). In addition, the circuit can easily stop the motor if you program a 0-Hz output frequency.