The hottest step based on spmc75f2413a MCU

2022-09-23
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Stepping motor acceleration and deceleration control based on spmc75f2413a single chip microcomputer

stepping motor (pulse motor) is an actuator that converts electric pulses into angular displacement. It is an actuator of digital control. It can control the speed and acceleration of motor rotation by controlling the pulse frequency, so as to achieve the purpose of speed regulation. Stepper motor has the advantages of large torque, small inertia and high response frequency, so it has the advantages of instant start and rapid stop. The biggest advantage of stepping motor in various applications is that it can be controlled in an open-loop manner without feedback to control the position and speed. However, it is precisely because the load position has no feedback to the control circuit that the stepping motor must correctly respond to each excitation change. If the excitation frequency is improperly selected and the motor cannot move to a new position, the actual load position will have a permanent error relative to the expected position of the controller, that is, out of step or overshoot will occur. Therefore, in the open-loop control system of stepping motor, how to prevent out of step and overshoot is the key to the normal operation of the open-loop control system

this design uses spmc75f2413a as the controller of the system design. Spmc75f2413a yes μ’ A new member of nsptm series products is a 16 bit microcontroller newly launched by Sunplus technology. In this design, spmc75f2413 generates pulse signals. The driving circuit uses sla7042m, a special driver for two-phase stepping motor produced by allergo company, to form the driving circuit of the stepping motor. The actuator is a two-phase hybrid stepping motor

1. Stepping motor acceleration and deceleration control principle

s curve acceleration and deceleration changes the traditional three-stage acceleration and deceleration process into a seven stage acceleration and deceleration process, forming an S-shape, as shown in Figure 1. The acceleration section is composed of acceleration section (T1), uniform acceleration section (T2) and deceleration section (T3); The deceleration section is composed of acceleration and deceleration section (T5), uniform deceleration section (T6) and deceleration section (T7); The constant speed section is (T4)

in the control system of the stepping motor, if the device of a dynamometer is tilted to the right, the included angle between the vertical line of the toothed bar and the push rod will increase the electric pulse signal, and the stepping motor will rotate an angle or advance a step. For example, if the number of pulses n is input, within the specified time t, its frequency, that is, the hydrogel is f due to its high water content and characteristics similar to extracellular matrix. The frequency f of the driving pulse varies with time t:

where FM is the highest continuous frequency of the stepping motor, τ It is a time constant that determines the speed of speed rise. In practice, it can be determined by experiments. The speed when the system reaches a uniform speed and the time it takes for the system to reach the maximum speed are known

this system uses the single-chip microcomputer to control the speed of the stepping motor in the way of timing interruption. In fact, it constantly changes the loading value of the timer when controlling the speed up and down

discretize the acceleration process, and fix the acceleration time as t=t1+t2+t3 in the design. For the convenience of explanation, make t2=0. At this time, the number of acceleration sections is changed from 3 to 2, namely, the acceleration section and the deceleration section. The shutdown condition shown is that the parameter t is divided into 40 equal time periods, that is, the acceleration time T1 is divided into 20 equal parts, and the acceleration and deceleration time T3 is divided into 20 equal parts. Then the interval between two speed changes is △ t=t/40, then the frequency of each gear can be calculated by formula (1), and the number of steps performed by the stepping motor at each gear frequency can also be calculated

2. System hardware design

Figure 2 is the structural block diagram of system hardware design. "Recycled materials from clear sources and reasonable recycling are processed into plastic express bags

in Figure 2, spmc75f2413a is a 16 bit microcontroller of a series of products. The working speed within the working voltage range of 4..5 V is MHz, with 2K word SRAM and 32K word flash ROM; IOA ~ iod4 groups of 64 bit programmable I/O ports, five general-purpose 16 bit timers/counters. The system uses the iob0 ~ iob3 bits of the iob port of s17mc75f2413a as the The output port of the control signal, with bit iob4 as the input port of the photoelectric sensor

stepping motor is easy to interface with digital circuit, but the signal energy of general digital circuit is far from enough to drive the motor. Therefore, there must be a matching driver to drive the stepping motor. The driver tells the motor how many microsteps it needs to run by providing a specific exciting current to the motor winding. When the stepping motor operates in the full step mode, it just coincides with the mechanical design characteristics of the motor. At this time, the stator and rotor teeth are exactly aligned, and the current flowing through the winding is the largest, and the step angle is also the largest. With the increase of fineness fraction, the step moment angle decreases correspondingly

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