I'm going to show you how to use your Arduino to control up to 12 servos at once with minimal jitter. Using a simple serial interface you can control the position of up to 12 servo channels. Up to 10 snapshot positions can be saved and played back at any time. Start up values for each servo can be saved as well.
There are two major parts to the application. The first part I will discuss is the firmware and hardware. This includes the Arduino and another board we will use to supply power to the servos. It's important to isolate the servo power supply from the microprocessor power in case the servos need more current than the battery can supply (imagine all 12 servos stalling at once). If the power supplies are the same you could have a brownout condition on your microprocessor depending what type of power supply you are using. I will also show you the firmware required to run this application on the Arduino.
In the second part I will discuss some simple software that will allow you to control the firmware through serial commands. This software provides an interface to the Arduino firmware to control the servos, save servo start up positions, even record a series of positions, or frames, (of all channels saved at once) to playback in sequence when desired. The software is .Net based so make sure you have the latest .Net framework installed. I will be supplying an installer and source code.
Here is a video demo of the project:
Step 1: Parts List
The following is a list of material and items I used for this instructable:
1x Arduino Board (Any variant that has a 328p processor)
1x Battery 6.0-8.0Vdc (I used an 800maH LiPoly battery)
1x 1N4004 Diode
2x 220uF 35V Electrolytic Capacitors
4x 3 Pin Headers (Use as many as you have servos for, I used 4 for this example but the firmware supports up to 12, just repeat)
4x 100 ohm resistors (1 for each servo. These are used for current limiting. At 3.3v the resistor limits the amount of current through the microprocessor at 3.3ma if a low impedance load is seen)
1x Small LED
1x 470 ohm resistor
1x Switch (I used a DIP switch for simplicity)
4x Hobby Servos
Various Jumper Wires