Stepper Motor Driver

This scheme is designed for use in a numerical control device, therefore, the clock signal, and the rotation direction signal switch system should come from external control devices.

Schematic diagram of the controller of the stepper motor shown in Figure 1.

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It consists of two interacting L297 and L298 chip from STMicroelectronics. chip L298 – This power stage, containing in their structure two H-bridge, a chip L297 – this controller, generating signals, control IC L298. It generates PWM signals in accordance with a predetermined motor windings current and rotational speed.

The controller provides a motor control with a maximum phase current 2A. It can manage bipolar 4-wire, unipolar 6-wire and 8-wire universal motors in steps 1/1 and 1/2 steps (micro step), set by a jumper H / F. By dividing the step into two main engine, doubling the resolution of the engine speed. However, it should be remembered, that the installation step for dividing 2 you must submit to 2 times the control pulses for rotating the rotor. The maximum rotor speed is also decreased, due to the frequency characteristics of the stepping motor.

Controller requires only three control signals, connected to the connector JP4. it:

  • CLK – clock signal, the frequency of which determines the speed and number of steps,
  • TO YOU – rotation direction signal,
  • ENABLE – Activation of the cascade of power controller.

High level activates a power level and a so-called brake, low, decelerates the motor. On JP4 connector also must be supplied voltage +5 In digital circuits. Power supply for circuit L298 power to be supplied from a separate power supply to the screw joint. This voltage should not exceed 40 AT, but the efficiency depends on the current, consumed by the motor. recommended, to stress, applied to the logic part, appeared before the advent of the, supply voltage, food. Two controllers can be connected in parallel, increasing the phase current. A method of synchronization is shown in Figure 2.

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On the picture 3 shown, how to connect the 4-wire bipolar motor, and Figure 4 shows 6-and 8-wire motors.

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motor rotation direction can be easily changed by replacing one pair of wires, for example AB BA.

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Driving device assembly shown in Figure 5.

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The controller is configured bilaterally using glass fiber through elements. To increase the cross section of the tracks, they need to tin or to add to them a copper conductor. Finally, secure power radiator (using self-tapping screws). Note: L298 chip housing is internally connected to the system ground! Finally, connect the motor in accordance with figure 4 or pattern 5 and adjust the winding current using potentiometer PR1. This current is best measured using an ammeter, connected to the motor coil circuit.

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