Controlling RC Car with RX-2B Receiver using Arduino Uno

Using Arduino Project Guidance
#1
  1. Unscrewed RC Car
  2. No VCC found on IC RX-2B, VDD found on RX-2B receiver IC. Hence assumed VDD as VCC.
  3. Connected Arduino 5V to VDD of Battery (Battery was connected to VDD of IC), Arduino GND to Battery other pin( Battery other pin connected to GND of IC indirectly)
  4. Identified the F,B,L,R pins of the RX-2B receiver and noted the wires running from F,B,L,R pins of RX-2B to the motors of the car.
  5. Directly soldered the 4 pins (8=F,7=B,2=L,4=R) of Arduino to Car motors through wires by taking into consideration step 4 (The car motor wires that were already soldered to RX-2B receiver was not touched or altered)
  6. Uploaded the Arduino Code
  7. The Arduino was plugged to the computer through USB

Issue 1. After uploading code to Arduino with Arduino powered through USB attached to computer, nothing happened. The wheels did not turn.
Issue 2. After disconnecting the Arduino and undoing all that was done to the car, the Car did not Function through its remote control
Issue 3. One of the wires on the car which is not part of F,B,L,R or VDD or GND or LEDs connected to RX-2B got disconnected. Unable to identify where to re-solder that wire on the RX-2B IC.

Final Note: RC Car not working

Need help and sugestions

#2

Issue 1: It's hard to help with this without seeing the code. And without Issue 2 and Issue 3 being resolved.
Issue 2: Probably due to Issue 3.
Issue 3: How can we help without even a clear picture? And what is at the other end of the unidentified wire that came off?

In other words, if anyone is to help you, you'll need to provide as much information as possible.

Directly soldered the 4 pins (8=F,7=B,2=L,4=R) of Arduino to Car motors through wires

Arduino pins can only sink/source an absolute maximum of 40mA, about 30mA or less is safe. If I'm to understand the above correctly, you're trying to drive the motors directly from the Arduino pins, without any sort of driver?

#3

What's a RX-2B?

R2-D2's cousin?

#4

DuaneDegn:
What's a RX-2B?

R2-D2's cousin?

You got it. :smiley:

Here's the datasheet:- RX-2B Datasheet

#5

Thank you. Issue 2 and Issue 3 mentioned above are resolved.

Issue 3 - The dangling wire is that of Antenna

The Arduino code is //taken from Instructables

/* Car Test Makes the modified RC car go in a figure 8. Plug the striped white wires into the Arduino pins as */ 
int forward = 8; // forward pin
int reverse = 7; // reverse pin 
int left = 2; // left pin 
int right =4; // right pin 

// The setup() method runs once, when the sketch starts 

void setup() 
{ 
// initialize the digital pins as an outputs: 
pinMode(forward, OUTPUT); 
pinMode(reverse, OUTPUT); 
pinMode(left, OUTPUT); 
pinMode(right, OUTPUT);
} 

void go_forward()
{ 
digitalWrite(reverse,LOW); // turn revers motor off 
digitalWrite(forward,HIGH); // turn forward motor on 
digitalWrite(left,LOW); 
digitalWrite(right,LOW); 
} 
void go_reverse() 
{ 
digitalWrite(forward,LOW); // turn forward notor off
digitalWrite(reverse,HIGH); // turn reverse motor on
digitalWrite(left,LOW); 
digitalWrite(right,LOW); 

} 
void stop_car() 
{ 
digitalWrite(reverse,LOW); // turn revers motor off 
digitalWrite(forward,LOW); // turn forward motor off 
digitalWrite(left,LOW); 
digitalWrite(right,LOW); 
}
void go_left() 
{ 
digitalWrite(right,LOW); // turn right motor off 
digitalWrite(left,HIGH); // turn left motor on 
} 
void go_right() 
{ 
digitalWrite(left,LOW); // tune left motor off 
digitalWrite(right,HIGH); // turn right motor on 
} 
// the loop() method runs over and over again, // as long as the Arduino has power 
void loop()
{ 
go_forward(); 
delay(1000); 
go_right(); 
delay(3000); 
go_forward(); 
delay(1000); 
go_left(); 
delay(3000); 
go_forward(); 
delay(1000);
go_right(); 
delay(3000); 
}

Now I have done the following steps without altering the wire connectivity already done on the toy car

Step 1: Connected GND of Arduino to GND of RX-2B.
Step 2: Connected the VDD of RX-2B to 5V of Arduino (Yellow and While Light appeared as soon as I did this)
Step 3: Connected the F Pin of RX-2B to 8 of Arduino (male-male wire) and so on for other directions as given in the code

Nothing happened. But the car works when I use its remote control.

Can any one tell me where I have gone wrong or what else I need to do.

#6

You really should have read the How to use this forum - please read post at the top of the index page and How to use this forum before posting.

ie Your code and any error messages should always be placed between code tags. Posting it inline as you have done makes it much harder to read or copy and paste for diagnosis.

It's still not too late to edit your post and do this. You'll make potential helpers much happier. :slight_smile:

Edit: And could you please provide us with a link to the relevant "Instructable"?

Isn't the "F" pin of the RX-2B an output? So you're connecting an RX-2B output to an Arduino output. Yes?
This is an RX-2B:-

#7

Link is http://letsmakerobots.com/content/rc-arduino-hack

Yes I am connecting the RX-2B output to the Arduino Output.

#8

jasma2002:
Yes I am connecting the RX-2B output to the Arduino Output.

You can't do that. You could potentially damage the receiver chip's output pins, the Arduino's output pins, or both.

I just quickly read that page you linked. It's only for reading the receiver pins, to determine their purpose. It says nothing about connecting and writing to them.

If you read the page carefully, it connects to each pin and lights a LED if the pin responds when each command is sent from the transmitter. That's all it does.

Note that in the following, he makes the Arduino pins that connect to the receiver chip inputs, not outputs:-

pinMode(frontpin, INPUT);    //declaring RC pins as inputs
pinMode(backpin, INPUT);
pinMode(rightpin, INPUT);
pinMode(leftpin, INPUT);

What sort of controller do those pins on the receiver chip connect to?
What you really need to do is work out which pin is which, (which you seem to already know), disconnect the wires from the RX chip/board, or use another method to isolate the Arduino from the RX chip and vice versa, then connect the Arduino so that it sends the controls to the controller, not to the RX chip AND the controller.

You need to show us a diagram of the whole setup. Receiver chip, motor controller, motors and the power connections to everyting. Then we can help.
Meantime, if I were you I would not power up the Arduino while connected in the way that it is, to avoid damaging anything.

I hope I've explained this well enough. There is a little more to it than you thought. That hack only shows the very first step of the process. It looks like he never went back and completed the job.

#9

What is the goal of this project?

Is it to control the car independ from the transmitter? Do you want the Arduino to control the car instead of the radio?

If so, I think the best thing to do would be to remove the RX-2B chip. It would be nice if you first learned which pin did what to control the car.

#10

DuaneDegn:
If so, I think the best thing to do would be to remove the RX-2B chip. It would be nice if you first learned which pin did what to control the car.

This part she has right. Unfortunately it’s the only part, so far.

#11