Servos are a special type of motor. They come in two different types: standard and continuous rotation. Standard servos rotate to a specific point (and stay there) based on the input signal. These types are widely used in radio controlled (RC) applications. For the Boe-Bot drive wheels, we’re using the continuous type.
Continuous rotation servos need be calibrated or “centered”. If a servo has not yet been centered, it may turn, vibrate, or make a humming noise when it receives the “stay-still” signal from the microcontroller.
You will use a small Phillips screwdriver to adjust the servos so that they actually stay still while receiving the “stay-still” signal from the BASIC Stamp microcontroller. We call this centering the servos.
You’ll need the Phillips screwdriver that came with your Boe-Bot kit (Phillips with a 1/8 inch (3.18 mm) or smaller shaft).
DO speedLeft = 0 speedRight = 0 time = 30000 GOSUB Wheel_Speeds LOOP
Your Boe-Bot may start spinning one or both wheels, in either direction.
This short program is sending the “center off” command to each of the servos, and by fine-tuning both of them, they will be completely stopped when this command is received by the servos.
Your Boe-Bot’s servos should now be calibrated and "centered".
Links
[1] https://learn.parallax.com/sites/default/files/content/sic_mini/BSA-Boe-Bot/Center%20Servos.zip