Stepper driver steps not accurate

Other Hardware Motors, Mechanics, Power and CNC
11

Try this version

#include <AccelStepper.h>

AccelStepper tableSlider(AccelStepper::DRIVER, 5, 6);

const int button = 2;            // pin button is on
int val = 0;                     // current button state
int old_val = 0;
int state = 0;
unsigned long previousMillis = 0;


void setup() {

    pinMode(button, INPUT_PULLUP);
    tableSlider.setMaxSpeed(1000);
    tableSlider.setAcceleration(400);
}

void loop() {

    unsigned long currentMillis = millis();
    if (currentMillis - previousMillis >= 100) {
        val = digitalRead(button);
        if ((val == LOW) && (old_val == HIGH)) {
            state = 1;
        }
        previousMillis = currentMillis;
        old_val = val;
    }
    if (state == 1) {
        tableSlider.move(-400);
        state = 0;
    }
    
    tableSlider.run();
}

...R