cs2508_pwm.c

void pwmFd(float on, long duration) {
    pwmAbstract(0, 0b00000011, on, duration);
}


void pwmBk(float on, long duration) {
    pwmAbstract(1, 0b00000011, on, duration);
}

void pwmAbstract(int directionNumber, int motors, float on, long duration) {
    long onTime = (long) (on * 100.0);
    long offTime = 100L - onTime;
    long totalTime = 0L;
    if (directionNumber) directionNumber = 255;
    while (totalTime < duration) {
        long timeLeft = duration - totalTime;
        long thisOnTime;
        long thisOffTime;
        if (timeLeft < onTime) thisOnTime = timeLeft;
        else thisOnTime = onTime;
        engageMotors(motors, directionNumber);
        msleep(thisOnTime);
        totalTime += thisOnTime;
        if (thisOnTime < onTime) break;
        timeLeft = duration - totalTime;
        if (timeLeft < offTime) thisOffTime = timeLeft;
        else thisOffTime = offTime;
        disengageMotors(motors);
        msleep(thisOffTime);
        totalTime += thisOffTime;
    }
}

void engageMotors(int motors, int directions) {
    int i;
    for (i = 0; i < 8; i++) {
        if (motors & (1 << i)) {
            if (directions & (1 << i)) {
                bk(i);
            }
            else {
                fd(i);
            }
        }
    }
}

void disengageMotors(int motors) {
    int i;
    for (i = 0; i < 8; i++) {
        if (motors & (1 << i)) {
            off(i);
        }
    }
}

void main() {
    pwmFd(0.3, 1000L);
}