Development of a Hybrid Stepper Motor Driver Based on L297/298 Chip Wang Pengfei, You Bo (College of Mechanical Power Engineering, Harbin University of Science and Technology, Harbin 150080, Heilongjiang, China) The sub-drive operation is stable and reliable, and the stepping and positioning accuracy is improved, and the control is better. Fever. Hybrid stepping motors are widely used in CNC machine tools, robotics, remote control, aerospace and other fields, especially the development of micro-computers and microelectronics technology, so that stepper motors have gained wider application. However, disadvantages such as large step angle, low resolution, and easy heating do not always meet industrial precision positioning and large torque control. When the phase current of the motor winding rises and the voltage of the sampling resistor rises to the reference voltage 1, the comparator flips. The flip-flop is reset, the power transistor is turned off, and the current drops, waiting for the arrival of the next oscillation pulse. In this way, the output of the trigger is a constant-frequency PWM signal, and the output signal of L297 is modulated, and the peak value of the winding phase current is set. Comparator sense resistor voltage L297 Internal chopper circuit schematic L297 Monolithic stepper motor controller IC For 3 hardware architecture Bipolar two-phase stepper motor or unipolar four-phase stepper motor control. Using the L297 output signal to control the L298 dual H-bridge drive set From the above, we can see that L297 has a chopper constant current circuit, around the DAC0832 enable signal set phase current peak by the tuning, therefore, the basic idea of ​​the driver hardware circuit design is The L297 is equipped with a suitable RC network to adjust the chopper oscillation pulse frequency. At the same time, the use of the 8751 produces a step-by-step variation in the subdivision voltage that is consistent with the L297 phase sequence, and is used as the input pin of the L297 to control a Ref input terminal of the winding phase current peak at the time of the chopper, and therefore, in the actual circuit. The design uses double L297 single L298 structure form. Drive part of the circuit. In the course of using the 8751 to generate subdivision voltages that are consistent with the L297 phase sequence, the subdivided voltage generation circuit, for example, externally transmits a certain frequency pulse signal to the 8571 external interrupter after optically isolating it from the idle optical port 6N137. 1 and counter 0, where counter 0 operates in mode 2, ie an 8-bit counter that automatically reloads the initial value. Since the counter 0 interrupt is one level higher than the external interrupt, there is no need to set the interrupt priority level. When the external pulse signal is input, the counter is incremented. When the counter register overflows, the counter 0 interrupt is triggered. In the interrupt response function, let P10 port of the one-chip computer outputs the corresponding pulse signal, after being reversed and send to CLOCK pin of L297. In the subsequent triggering of external interrupt 1, the count variable is incremented by one, and the array variable with the count variable as the subscript is output to port P0. Then the 8-bit digital-to-analog converter of DAC0832 is used to send the generated step voltage to L297. Pin. In this way, not only the subdivision dual L297 single L298 structure driving part hardware circuit diagram step motor subdivision voltage generating circuit 39 tastes the array value of pressing is realized but also the variable details with high subdivision number can be realized. In order to realize subdivided driving of the stepping motor, it is necessary to take out the corresponding subdivision code at an appropriate time, and at the same time, it is required to complete only one subdivision cycle output when the phase sequence of each motor changes. EPROM firmware program flow chart, for example. 4 Experiments and conclusions The hybrid stepping motor driver has been successfully applied to the motion control drive unit of the XY numerical control platform. Through the development of the control software under the Win-environment, a well-designed control interface interface using VC++ is used to facilitate the stepping. Motor drive. The drive unit improves step accuracy and positioning accuracy by subdividing features. In the long-term high-moment drive process, the heating phenomenon is better controlled due to its chopping constant current characteristics. Drive power EPROM firmware block diagram Bathroom Floor Drain,Bathroom Long Stainless Steel Floor Drain,Stainless Steel Black Floor Drain,Stainless Steel Bathroom Floor Drain Kaiping City Jinqiang Hardware Products Co.,Ltd , https://www.jqfloordrain.com
Development of a Hybrid Stepper Motor Driver Based on L297298 Chip