Stepper Motor Design Idea
Function module design
The module can be divided into the following three parts:
single-chip system:control stepper motor;
peripheral circuit:PIC microcontroller and stepper motor interface circuit;
PIC program:program the single-chip control stepper motor interface program to achieve the triangular wave signal output function.
(1) stepper motor and microcontroller interface.
The microcontroller is an excellent control processor,and the interface components must have the following functions when control the stepper motor.
① voltage isolation function.
The microcontroller operates at 5V, while the stepper motor is operating at dozens of V, or even higher.Once the stepper motor voltage string to the microcontroller,it will damage the microcontroller;stepper motor signal will interfere with the microcontroller,may also lead to system failure,so the interface device must have isolation function.
② information transfer function.
The interface component is able to transmit the control information of the microcontroller to the stepping motor circuit to produce the control information required for the operation.Corresponding to the different working modes,the interface part should be able to generate the corresponding working control waveform.
③ produce the required different frequencies.
In order to make the stepper motor work at different speeds to suit different purposes,the interface components should be able to produce different operating frequencies.
(2)Voltage isolation interface.
The voltage isolation interface is designed to isolate the low-voltage part of the microcontroller and the high-voltage part of the stepper motor drive circuit to ensure their normal operation.Voltage isolation interface can use pulse transformer or optical isolator,now basically use optical isolator.
The microcontroller output signal pass through the TTL gate circuit or directly send to the base of transistor,and then transistor drive the optocoupler device light-emitting diode.
Light-emitting diode light shine to the inside photosensitive tube of photoelectric coupling device,convert into electrical signals,then drive the stepper motor power amplifier circuit,the current amplifier interface is the stepper motor amplifier circuit preamplifier circuit.Its role is to enlarge photoelectric isolator output signal current,in order to provide a sufficient driving current to amplifier circuit.
(3)Working mode interface and frequency generator.
Use single-chip to control stepper motor,need to connect three I / 0 line on input and output interface to control stepper motor ,at this time,single-chip use I / O port RA0, RAI, RA2 to control stepper motor three-phase.