Full Servo support only available in ScratchGPIO6 https://cymplecy.wordpress.com/2013/11/26/scratchgpio-development-testing/
Servos are very useful little devices. They let turn them about through 180 degrees (half a circle) and hold their position.
So they are very useful to control the position of the Pi camera or robot arms or lift pens up and down.
YOUR PI MUST BE SWITCHED OFF BEFORE CONNECTING OR DISCONNECTING SERVOS
The most popular ones come with 3 pin socket – Brown is Gnd, Red is+ve and Yellow is the signal wire which gets connected to a Pi Pin.
Note: It is more reliable to connect the +ve wire to a separate battery but if you power your Pi from a good PSU then it will probably work.
To use, simply create a variable called servoX (where X is the pin you have connected the signal wire to). The servo values are from -100 to 100 with 0 moving the servo to its centre position.
All servos behave differently and not all will take the maximum or minimum values of 100 and -100. If you find your servo is making “funny noises” then try using values of 90 and -90 or even smaller if needed
Using Adafruit 16 Servo/PWM board
Adafruit produce a very nice board with ability to very accurately generate pulses for motors and servos
To use it with ScratchGPIO use variables AdaServo0 to AdaServo15 with values from -90 to 90 as above