Introduction to the EMGRobotics Quad RC Servo Controller Android Application

The EMGRobotics Quad RC Servo Controller application is an Android based 4-axis motion controller designed to run on your smartphone or tablet. Simply plug an A2SCB_ML (available from into the headphone jack of the smartphone or tablet and connect two servos to the A2SCB_ML. To control four RC servos, connect an A2SCB_S to the A2SCB_ML and plug two servos into the A2SCB_S, for a total of four servos (two plugged into the A2SCB_ML and two plugged into the A2SCB_S).

The A2SCB_ML and A2SCB_S can be ordered together as a package for $25.99.

The EMGRobotics Quad RC Servo Controller Android application uses four on-screen sliders to control the four servos. Moving a slider with your finger immediately moves the servo (when in edit mode). Servos are moved independently or together. After the servos are moved to the desired position, the 'Enter' button is used to save the position of all four servos. This process is repeated, resulting in a motion sequence. The individual entries in the motion sequence can be edited using the next and last buttons. After the motion sequence is complete, it can be saved to a file, exported to a BASIC program or WAV file, or played back. The playback rate is adjusted with the 'rate' slider.


The 'Ratios' entry lets the user set a multiplier for each servo channel. The multiplier has the effect of making the slider more or less sensitive. Decreasing the multiplier decrease the sensitivity resulting in the servo moving less for an equal movement of the slider. This is useful for applications like RC trucks or cars. Neither the steering servo nor the Motor driver require the full 180 degree motion. By decreasing the ratios, the range of the servos can decreased to better fit the specific application.


The EMGRobotics Quad RC Servo Controller application is perfect for automating art, or for simple robots that do not have sensors. The 'repeat' function can be used to repeat the motion sequence until stopped by the user. More complex robots or interactive art requires interaction with sensors. To use your motion sequence in other applications, the motion sequence can be exported as a RFO BASIC program or a WAV file.  


The BASIC export function writes a RFO BASIC program, designed to recreate the motion sequence, to an output file. You must have RFO BASIC installed for this to work correctly. Each sequence is encapsulated in a BASIC function so multiple motion sequences can be combined into a bigger BASIC application. RFO BASIC supports many of the sensors available in common smartphones. In addition, RFO BASIC supports the ability to send and receive text messages and emails.

The WAV feature exports the motion sequence as a WAV audio file. The WAV file is stereo with a 44100Hz sample rate. Any device with a headphone jack that can playback a 44100 stereo WAV file can be used to control the servos. Any Android application that can playback a WAV file can also control the servos.

Catroid is a graphical programming language, based on Scratch from MIT, designed for kids. Catroid also supports various smartphone sensors and can playback WAV files to control the servos.

The EMGRobotics Quad RC Servo Controller Android application is an easy to use tool for creating 4-axis motion control sequences. It can control up to four RC servos through an EMGRobotics A2SCB_ML and an A2SCB_S audio interface board. Motion sequences can be saved for later playback or played back in a repeat mode. Motion sequences can be exported as WAV files or RFO BASIC files. You can download the Quad RC Servo Controller for free from Google Play here:

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