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Topic: Hacking rc controller (Read 1 time) previous topic - next topic

johnricco

hi,

I am trying to hack a RC controller i have. The way the controller works is that it has two potentiometers. One for the throttle and one for the steering left to right.

Instead of building my own ir transmitter I hope to just replace the two pots with an arduino board. The controller uses a 6V supply which is made up of 4 AAA batteries but I am replacing that with my own power supply. I thought i would be able to replace the two pots with a MOSFET circuit ( https://www.sparkfun.com/products/10256). So I attached the pots to my arduino board and using the example here http://arduino.cc/en/Tutorial/AnalogInOutSerial I read the values, and determined what i should send to back to the controller. However regardless of the PWM values i send the remote never changes its state.

Does anyone have any ideas as to what I might be missing?


johnwasser

You can't generally replace a pot with a MOSFET switch.  The first task would be determining how the transmitter chip is sensing the pot positions.  Often that will be a voltage measurement, either by putting a voltage across the pot and sampling it with the wiper OR by using the pot as a variable resistor and using it and a fixed resistor as a voltage divider.

Once you figure out the range of voltages the chip expects you can use a PWM output (analogWrite()) and a filtering system (resistor/capacitor) to generate a suitable range of voltages.
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DuaneB

why not put the controller back together and put the arduino in the tank ? That way it can manage some sensors and operate in manual or autonomous modes ?

Just a suggestion

Duane B

rcarduino.blogspot.com

johnricco

The reading from the pots using the arduino sketch are as followed

POT 1
POS | Sensor | Values
right|   20    |    4
center|  599 |    148
left |  1024  |    255

POT 2
POS | Sensor | Values
right|   886    |    220
center|  589 |    146
left |  332  |    82

I also took the readings for the output voltage
POS | V
right|2.942
center|2.857
left|2.784

So the resistor and capacitor is a low pass filter circuit is that correct?
The values in the table above in the output column are what I should be using as the analogWrite() values?
Is there away for me to determine what value capacitor and resistor i should use in the circuit?

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