Using the RCX as an RC-servo control

The RCX in a very unusual application, controlling a non-LEGO robot:

At the "Trophée de robotique 2005" we were challenged with following question : is it possible to control 3 RC-servos? The reason was that a complete RC-servo driver kit didn't work at all, and there was no time left to get any other one.

Of course the answer was : Yes, it is!

The RCX  is a most versatile object and with powerful software like Ultimate ROBOLAB, there are literally endless unexpected and useful applications.

The solution to the challenge is an independent RCX firmware that assures the following functions:

• configure3 independent RC-servo motors
• configure 3 rotation sensors
• display a text that identifies the firmware clearly
• maintain the sensor values in the range 0..100
• continuously adjust the servos positions in function of the rotation sensor position
• send and receive data over the serial channel (get RC servo calibration data; send acknowledgement flag)
• adjust RC servo intercepts or slopes to calibrate the RC servos. Concerns: center and sensitivity

The second part of the solution is a PC program that allows to calibrate the RC-servos:

Download :

• servo control firmware
• ROBOLAB firmware downloader
• set slopes and intercepts program
• Ultimate ROBOLAB source program

The 3 RCX output ports send out the controlling oulse for 3 independent RC-servo motors. A 1kOhm protection resistor should be added in any case. The servos must be powered through an additional external battery.

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