Matsimitsu

# How to control an RC car with an arduino

- 3 minutes

A while ago me, @thijsc and @jkreeftmeijer each bought an arduino starters kit and after the first blinking light it ended up somewhere on my desk. Today i thought it would be fun to actually do something with it, so i went to the local Intertoys and bought a cheap RC car.

### Requirements

If you want to do the same i suggest you first try it with the cheapest RC car you can find that has:

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I ended up with the “Wild Hopper”, an offroad buggy.

wild_hopper.jpg

### Insides

Next step was to take the damn thing apart!

wild_hopper_hops_no_more.jpg

Inside i unscrewed the PCB to see if i could recognize anything. (Click for larger image with pin layout)

print_thumb.jpg

### Wiring

I Googled for the numbers on the PCB (SW188 top right on the PCB) and it turns out there is a Chinese (i’m assuming this by the look of the signs) document with the pin layout of the chip! Download the pdf here.

Now i had the pin layout it was just a matter of putting current on the pins and the wheels started moving! I also found out the front weels return to the center position after i disconnected the current. This is really great and saves me a lot of code. Next i soldered wires to the right pins and a wire to the ground. I added LEDs to all the channels so i could see if the right action was triggered.

wiring_complete.jpg

As you can see from the photo, I used digital pin 3 to 6 for the four channels (forwards, backwards, left, right)

With everything connected it was time to write the code. I wanted to achieve a simple 3 point turn, this would require all actions (forward, left, right backwards and stop) so i could see that everything was working ok.

### The code

The code is really simple, I initialize the pins for output and use that and delays to move the car around.

/*
  3 point turn, attempt 1
*/

void setup() {
  // initialize the digital pins as outputs.
  pinMode(3, OUTPUT);   // Forward
  pinMode(4, OUTPUT);   // Backwards
  pinMode(5, OUTPUT);   // Left
  pinMode(6, OUTPUT);   // Right

}
// Three point turn

void loop() {
  digitalWrite(3, HIGH);   // Forward for 1 second
  delay(500);
  digitalWrite(3, LOW);
  delay(2000);              // wait for a second

  digitalWrite(4, HIGH);   // Back left for half a second
  digitalWrite(5, HIGH);
  delay(500);

  digitalWrite(4, LOW);
  digitalWrite(5, LOW);
  delay(2000);            // wait for 2 seconds

  digitalWrite(3, HIGH);   // Back left for half a second
  digitalWrite(6, HIGH);
  delay(500);

  digitalWrite(3, LOW);
  digitalWrite(6, LOW);
  delay(2000);            // wait for 2 seconds
}

### Result

The end result of the day

### What’s next?

The next step will be adding sensors so it doesn’t crash into every object in the room. More about that in another post!