Driving a bipolar stepper motor using an ATTiny85

main.cpp

#include <Arduino.h>

constexpr int DRV_IN1 = PIN_B0;
constexpr int DRV_IN2 = PIN_B1;
constexpr int DRV_IN3 = PIN_B2;
constexpr int DRV_IN4 = PIN_B5;

class Winding {
public:
    const int pin1, pin2;

    constexpr Winding(int pin1, int pin2) : pin1(pin1), pin2(pin2) {}

    void setup() {
        pinMode(pin1, OUTPUT);
        pinMode(pin2, OUTPUT);
        coast();
    }

    void coast() {
        digitalWrite(pin1, false);
        digitalWrite(pin2, false);
    }

    void forward() {
        digitalWrite(pin1, false);
        digitalWrite(pin2, true);
    }

    void backward() {
        digitalWrite(pin1, true);
        digitalWrite(pin2, false);
    }

    void brake() {
        digitalWrite(pin1, true);
        digitalWrite(pin2, false);
    }
};

class Stepper {
public:
    Winding a,b;

    constexpr Stepper(Winding a, Winding b) : a(a), b(b) {}

    const void setup() {
        a.setup();
        b.setup();
    }

    void nthstepfwd(int n) {
        switch(n%8) {
        case 0:
            a.backward(); b.coast();
            break;
        case 1:
            a.backward(); b.forward();
            break;
        case 2:
            a.coast(); b.forward();
            break;
        case 3:
            a.forward(); b.forward();
            break;
        case 4:
            a.forward(); b.coast();
            break;
        case 5:
            a.forward(); b.backward();
            break;
        case 6:
            a.coast(); b.backward();
            break;
        case 7:
            a.backward(); b.backward();
            break;
        }
        delayMicroseconds(1000);
    }

    void stepfwd(int n) {
        for(int i = 0; i != n; ++n) {
            nthstepfwd(n);
        }
    }
};

Stepper stepper(Winding(DRV_IN1, DRV_IN2), Winding(DRV_IN3, DRV_IN4));



void setup() {
    stepper.setup();
}

void loop() {
    for(int n=0; n != 8; ++n) {
        stepper.nthstepfwd(n);
    }
}