I have a quadcopter (Syma X5C) that I really want to control with an Arduino. Since I have the ability to write programs to my Arduino to make the quadcopter fly autonomously, I want to modify my "hack" my quadcopter remote to allow the Arduino to be interfaced with it.
After opening up my quadcopter remote, I figured that the fastest way for me to programatically fly my quadcopter is to desolder and remove the existing two joysticks and replace them with digital potentiometers which will be controlled by the Arduino.
I almost thought I could do this, however, most digital potentiometers only use the SPI protocol to talk to the Arduino. If I need to control the 4 axes of the two joysticks, I would need more than one SPI digital potentiometers. Also, I am not sure my Arduino would work with more than one SPI module. I was trying to look for an I2C potentiometer, but I was not able to find any cheap ones available.
Is there a way I can control my quadcopter remote without the need to use a digital potentiometer? Please give me detailed suggestions, preferably with a diagram.