步进电机加速和中断

Question

I have to make a project where I have to control a stepper motor from buttons. I use an ATXMEGA256a3u microcontroller. When I start the motor it has to accelerate in a few seconds to a constant speed then at the end of the sequence it has to slow down and stop. I made a code to initialize and start the motor but I'm not so familiar working with stepper motors. My code to start the motor is: void startMotor(void) { PORT_STEP.OUT |= (EN1 + STEP1 + DIR1); PORT_STEP.OUT &= ~(EN1); PORT_STEP.DIR |= (EN1 + STEP1 + DIR1);

    while (1)
    {
        PORT_STEP.OUT |= STEP1;
        delay_us(100);
        PORT_STEP.OUT &= ~STEP1;
        delay_us(100);
    }
}

This way it runs constantly. Thanks for any help.

Answer 1

Well, it seems you are driving a "step/direction" stepper driver. These kind of driver make a step for every pulse.

To achieve different speeds you have to produce more or less pulses in the same time or, in other words, to change the delay (your delay_us(100)) in the cycle. With two "delay_us(200)" the speed will be halved, and with two "delay_us(50)" the speed will be doubled.

To make a ramp up, you start with long delays and reduce them up to the final value; to make a ramp down you make bigger and bigger delays until they are long enough to stop completely to generate pulses. The speed of change in delays will regulate the ramp slope (acceleration).

Last note: you use two delays - there is no need for them to be equal, probably you can take one fixed and operate on the other. But even changing both is not a problem (it depends on the application). If you driver can select different microstepping values (1/8192, 1/4096 or whatever) play also with those values, that could simplify your program.