This application is for controlling hobby servo motors with simple wire connected to your iOS devices headphone jack. Basically, this app will generate appropriate "PWM" signal as audio, then controls two servo motors.
In terms of using this application with hobby Servo Motors, you need to make your own "GlueMotor Cable" by yourself. Please refer to our web site http://www.GlueMotor.com/ or an article "SMARTPHONE Servo" in Make: magazine Volume 34, page 84 for more details.
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This application does not work with old devices such as iPhone 3G or iPod touch 2nd gen, however "GlueMotor" version 1.1 is still available for such old devices at here: https://itun.es/i6xd3VW