Page 67 - 15 Dangerously Mad Projects for the Evil Genius

46 15 Dangerously Mad Projects for the Evil Genius

Figure 4-20 Controlling more than one turret from a joystick

Unlike standard motors, a servo module does A pulse of 1.5 milliseconds sets the servo to
not rotate around and around. It can only travel its center position, a shorter pulse of 1.25
through about 180 degrees. The modules are milliseconds to its leftmost position, and 1.75 to
controlled by pulses of voltage on the control its rightmost position.
connection to the servo. The length of the pulse
The servo motor expects there to be a pulse at
controls the angle to which the servo is set.
least every 20 milliseconds for the servo to hold
Figure 4-21 shows an example waveform. You its position.
can see how the width of the pulses varies the
servo angle.