Move robot set number of steps (Arduino) - c

Question

I want to move my robot a set number of steps and then have it stop. However the loop just seems to run on infinitely. Is there a mistake in the way that I am using void loop() or perhaps in the way that I have written my 'for' loop?
// walkerForward.pde - Two servo walker. Forward.
// (c) Kimmo Karvinen & Tero Karvinen http://BotBook.com
// updated - Joe Saavedra, 2010
#include <Servo.h>
Servo frontServo;
Servo rearServo;
int centerPos = 90;
int frontRightUp = 75;
int frontLeftUp = 120;
int backRightForward = 45;
int backLeftForward = 135;
void moveForward(int steps)
{
for (int x = steps; steps > 0; steps--) {
frontServo.write(centerPos);
rearServo.write(centerPos);
delay(100);
frontServo.write(frontRightUp);
rearServo.write(backLeftForward);
delay(100);
frontServo.write(centerPos);
rearServo.write(centerPos);
delay(100);
frontServo.write(frontLeftUp);
rearServo.write(backRightForward);
delay(100);
}
}
void setup()
{
frontServo.attach(2);
rearServo.attach(3);
}
void loop()
{
moveForward(5);
}

Answer 1

the loop() function is executed within an infinite loop (if you check the main cpp file that ships with the Arduino IDE, you'll see something like this:
int main()
{
setup();
for (;;) {
loop();
}
return 0;
}
So either put the call to your moveForward() function to setup() and make loop() an empty function, or call exit(0); from within loop() after moveForward(). The first approach looks like this:
void setup()
{
frontServo.attach(2);
rearServo.attach(3);
moveForward(5);
}
void loop()
{
}
And the second one looks like this:
void setup()
{
frontServo.attach(2);
rearServo.attach(3);
}
void loop()
{
moveForward(5);
exit(0);
}

Answer 2

Since you probably will want to eventually do more than move the robot just 5 steps, I'd suggest using a variable flag to hold the robot state. It only executes the movement routine when the flag has been set to true.
If you are using serial, when a move command is received (and the number of steps, direction perhaps?) you set the flag to true and then issue the move command. If you are using sensors or buttons, the same logic applies.
You will need some logic to handle an incoming movement command while a movement is occurring (though with your tight movement loop you actually won't be able to respond to incoming commands unless you use interrupts - but you want to consider this sort of thing if you are planning to build out a full movement bit of firmware).
boolean shouldMove;
void setup()
{
shouldMove = true;//set the flag
}
void loop()
{
if (shouldMove){
moveForward(5);
}
}
void moveForward(int steps)
{
shouldMove = false; //clear the flag
for (int x = steps; steps > 0; steps--) {
// tight loop controlling movement
}
}
}