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I have a WL v262 quadcopter and I want to control it using Arduino instead of the joysticks on the transmitter. I opened up the transmitter and saw that each joystick has 2 potentiometers on the PCB and that the voltage for each pot goes from 0-3.3V. I used arduino's PWM and a low pass filter and connected the output of the filtered output to the potentiometer's analog pin which is connected to the PCB (I cannot desolder and take out the pots from the PCB) but even with this $V_{out}$ going onto the analog pin, my transmitter's display gave ????

Now I am really confused and frustrated because I don't know how else to control this transmitter other than attaching stepper motors to the joysticks and manually controlling the transmitter but this is really my last resort. Can someone help me with this? I have spent hours and hours trial and error but I am getting nowhere.

Here is the PCB of the transmitter:

enter image description here

enter image description here

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up vote 1 down vote accepted

Did it actually output only "????" Does removing the PWM restore normal operation? It is likely that the load from the PWM is not initially within correct voltage range at RC's bootup and it is detecting this and faulting. With the Pot's still inplace the range will be limited, but you could try to match it. Initially (and even while ????'ing) try to set the PWM's output to be the same voltage as when it is not connected. This may solve your ???? problem.

I also note from your picture the Transmitter module at top between joy sticks. I would suspect that you can better decipher the stream of information sent into this module by the controller and send your own information. This would be similar to what I did for IR Helicopter controllers

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yes. You are right: When the transmitter is turned on, I have to move the joystick all the way at low position and move it to highest position and then back to low position. After I have done this, any movement of the joystick will start flying the quad. So maybe I can try inputting 0 V then 3.3 V then 0 V at the pot with my PWM and see if this starts it up and prevents the ????. One issue I found is that when I measure just the vout from low pass filter, I get all the values I programmed the arduino to PWM from 0-2.7 but when I PWM 3.3 V or higher, it wont go higher on pot.. – Raynos Dec 3 '13 at 21:05
I have read online where someone uses that black chip you see on the PCB (It is apparently an encoder) to control the output that goes to the transmitter. I don't know how to do this so I am either going to keep trying this PWM method, a digital pot attempt, and as a last resort, mount servos on the transmitter to mechanically control the joysticks..I – Raynos Dec 3 '13 at 21:07
I feel much more safe and secure with my attempts knowing that I have someone I can consult to ask and discuss about this project to get this working so thank you for the help. – Raynos Dec 3 '13 at 21:10

Search for a Digital Potentiometer. It's exactly what you're looking for. Just replace the manual pot's with them and you can use serial connections to control the voltage.

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I have the answer because I´ve the same problem, you can use a PWM but need use a RC low pass filter in the output

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Welcome to robotics ivan, thanks for our answer but we prefer answers to be self contained where possible. Links tend to rot so answers which rely on a link can be rendered useless if the linked to content does rot. If you add more context from the link, it is more likely that people will find your answer useful. – Mark Booth Mar 27 '15 at 17:06

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