one pad have 1 axis pot. the other one have 2x1axis combined, i have to interface my arduino to this joystick to drive an rc car by serial data. i know that i may reproduce radio signals without connecting to the joypad, but this way seems quite faster.
now my question is, how do i emulate potentiometer with arduino ? using analogWrite with max value as max value is the pot output ? ( if the use potentiometer connected to the vcc and not to something else...)
some of ya already experienced something similar ?
You can get digital potentiometers that can be controlled by Arduino, and replace the 2 (3) pots in the joy pad controller thingie.
You will have to start measuring the resistance of the 3 pots in the controller to figure out which digi. pots to get.
But remember that when pots are used in joysticks usually only a part of the pots track is used so the total resistance is never used, AND more important the resistance never drops to 0 because the pots wiper never reach the "far left side" of the resistive element in the pot.
You should measure the min, and max. resistance with the joystick handle maxed out to both sides.
You might want to look into digital potentiometer ICs; linear taper, likely - not audio taper. Audio taper ones are used in digitally controlled radios and amps for volume control. Essentially they take a digital value (of varying bit lengths depending on the application) and use that to create a varying resistance internally. You would just need to find one with the number of bits needed (ie, 8 bits for 256 values) and the size of potentiometer resistance (ie, 100K) to use in your application. I would imagine that many nowadays use I2C for control, so they would be easy to interface to the Arduino (older ones used separate lines on the chip for each bit of input).
Alternatively (and probably easier to understand, though less accurate) you could devise a scheme to attach the potentiometers from the radio to R/C servos, then drive the servos with the Arduino.
A digi_pot is the way to go as long as the range of voltage seen at the existing pot don't exceed 5v..... I couldn't find any chips that could handle voltages above vcc and vcc is 5v or less (at least the datasheets I looked at). If this is the case you can use one of the PWM outputs of the arduino along with a transistor and a low pass filter to produce you varying voltage.
