Try the Continuous Servo

Warning: While the board is powered and the wires are connected in the Arduino board, do not to let the red and black wires touch as this could cause your board to break.

1. Disconnect the white, red, and black wires from the socket of the standard Servo.
2. Insert the same white, red, and black wires into the matching sockets of the continuous Servo.
3. Notice the Servo is rotating in one direction and then the other.

STEM Connections

The standard and continuous Servos move very differently, even when given the same instructions from the program you uploaded to the Arduino board. Remember, standard Servos move to specific angles and continuous Servos rotate in either direction at different speeds. Continuous Servos take in the same numbers (0 through 180) as standard Servos, but they interpret those numbers differently. They do not interpret the numbers to be angles, but instead they interpret these numbers as the direction and speed of their rotation. When translating those numbers into the direction of the rotation, continuous Servos interpret the number 90 as no movement, or stopped. A number that is greater than 90 is interpreted as rotation in one direction and a number less than 90 is interpreted as rotation in the opposite direction.

When translating those numbers into the speed of the rotation, the closer the number is to 90, the slower the Servo will spin, and the further away the number is from 90, the faster the Servo will spin. Therefore, when the Arduino board runs the line of code “myservo.write(0);”, it will spin fast in one direction and when it runs the line of code “myservo.write(180);”, it will spin fast in the opposite direction.The closer the number is to 180 the faster the servo will spin in one direction. The closer the number is to 0 the faster the servo will spin in the opposite direction.

1. Check to make sure that the wires are all connected to their corresponding color on the Servo connector.
    
2. Check to see that the program was successfully uploaded to the Arduino board by looking for the “Done Uploading” message on the Arduino software
    
3. Check to make sure that the wires are connected to the correct pins on the Arduino board.
   • Remember, Red – Vin, Black – GND, and White – Pin 9.
    
4. If all else fails, replace the Servo.
   • Note: It is not uncommon for Servos to break after repeated use.

1. Remember the same code works for both Servos but they behave differently. This also makes sure that both Servos are working before they start robo-crafting.
    
2. With the standard Servo, the number inside myservo.write( ); matches the angle it will point to, but the continuous Sservo is not as straightforward. It’s nice to visualize it by drawing a number line from 0 to 180. You can ask the students to help you draw it out. Label where 90 would be. If you type “myservo.write( 90 ); “ then the continuous Servo should stop. It might not be perfect so encourage trying to find the number that would make it stop for their particular Servo. It can be as high as 93 and as low as 87, but always close to 90. You can shade or draw an arrow to the right of 90 (90 –> 180) and write out which direction it spins. For us, it’s right, or clockwise, but we’ve seen continuous Servos where the opposite is true. Likewise, you can shade or draw an arrow to the left of 90 (0 <– 90) and write out which direction it spins. At the extreme end points, 0 and 180, the furthest points from 90, are the values that make the Servo spin the fastest. As you choose a number closer to 90, the Servo will spin slower.