$50 robot question

[ert481]

here is the code in the header file

Code: [Select]

void servo_left(signed long int speed)
{
PORT_ON(PORTD, 0);
delay_cycles(speed);
PORT_OFF(PORTD, 0);//keep off
delay_cycles(200);
}how can i change it so the robot can go backwards?
you cant do this servo_left(-50)
because you cant delay the cycles for -50.
so how can i change it so i can?