RC car + Arduino UNO

I am doing a small side project and I ran into a bit of a roadblock. I have an RC car which I removed the Realtek RX2/TX2 chip which used to control the car. I Connected the pins for each control ( forward, back, left, right) to the Arduino Uno (pins 13,12,11,10) and the ground from the RC car to the GND of the Arduino. I had written a simple sketch which when 'a' was entered in the Serial Console pin 13 was set to high and the car would go forward.

The sketch worked but every time I pressed 'a' the Serial Console would crap out and crash and I would have to close everything, unplug the Arduino in order to get the serial connection back up. Now the Arduino still lights up and responds to the reset button but the computer will not recognize it as a device. I have tried it in 2 different PCs with different USB cables and still nothing, so I'm guessing I fried the USB host on the Arduino.

My question is was I supposed to introduce resistors between the RC controls and Arduino? (BTW the RC car has a 9.6 V battery but the "logic" circuit is 5V)

I would like to figure out what I did wrong so I don't end up with two fried Arduinos.

Thank you.

Without looking at the schematics it is difficult to pinpoint exactly what was the cause. But most likely, it is due to the large voltage discrepancies. The easiest way to isolate these two voltages is to use opto-isolator.

I have used Arduino to control an off-the-shelf RC car using the method I mentioned above. Good luck!

Thank you, the opto-isolator seams like the perfct solution to my problem. I would like to figure out why the Arduino shorter out in the first place. I'll post the schematics for the Rc car circuit later when I get home.

Once again thank you.

Here is the suggested circuit for the RC control chip.


Also would this optocoupler meet my needs?


The optocoupler you mentioned looks more than adequate. I used the commonly available 4N25/4N35.