RC car RX2 chip with arduino

Hello!!

i have found an old rc car without remote controller at home. I want to interface arduino with chip in the car, but i don´t know how to do it :(...

Datasheet of the RX2 chip in the car is here: http://www.jbprojects.net/projects/wifirobot/TX2RX2.doc

I have arduino and rc car, but i don´t have elektrical knowledge :(...
Please tell me which pins of RX2 connect with arduino pins and how :)...

If somebody knows how to interface RX2 with arduino please post it here! Thank you!

Without the transmitter your going to have a hard time getting anything to happen with this thing...

Pin 3 on the RX2 is the pin which receives the radio signal, the physical connection won't be very difficult, you'd connect pin 3 of the RX2 to a digital pin on the arduino.

Making the code work is going to be a challenge, you will need to send a pulsing signal from an arduino digital pin, the specification of the pulse can be seen on page 4 of the data sheet.

My coding skills aren't good enough to take that information and create functions, if I were doing this I would completely remove the original controller board, and use the arduino in it's place with appropriate circuits to directly drive the motor and (if it uses one) servo.

Here is what you'll have to do - and I am NOT going to hold your hand:

  1. Get the examples working with the Arduino. Do some googling on basic electronics. Learn to read schematics and datasheets. Take your time, don't be impatient. Respect electricity.

  2. Practice learning to solder and build circuits; that, or get a good education and career so that you can pay $$$ to people like me to build it for you.

  3. Provided you have steps 1 and 2 complete, continue to step 4.

  4. According to the spec sheet for the receiver chip (in the car), the pinout is as follows: RX2 Pin 6 = Right, RX2 Pin 7 = Left, RX2 Pin 10 = Backward, RX2 Pin 11 = Forward, RX2 Pin 12 = Turbo.

What this means is that on this chip, upon receiving the commands from the transmitter, interprets them and then outputs TTL logic HIGH (5V) on those pins; those pins (most likely) lead to some transistors in the form of an H-Bridge for the drive wheels, and likely some kind of transistor control for the steering and/or "turbo" function (which could really be anything - or it might not be connected; think of it as a "3rd channel", that can be used for a variety of functions - does this vehicle have any special functions?).

So - locate those pins coming out of the RX2 chip; look at the RX2 chip on the PCB in the car, and orient it in the same manner as on the spec sheet; pin 1 is on the upper-left corner, counting continues down the left side, and then up from the bottom on the right side. Note where all the pins are, and which holes they are on the PCB (or traces). You may want to use a multi-meter to trace from the pins to the respective connected component (likely a base bias resistor if transistors are being used). Also note the ground pin (pin 2). I can't tell what kind of chip this is (PDIP or SMT-type) from the spec, so keep this in mind.

Once you know where the leads go to, you are going to want to remove the chip (or clip the leads being used). This is so when you interface the Arduino to it, you are inadvertently powering it or something strange; it would be best to remove it completely if you can. Desolder it, or clip/cut the leads (being careful not to damage other nearby components or traces). After you have it disconnected, connect up new wires to the holes where the pins in question led; you may want to color-code them; if you plan on running the Arduino off the battery in the car, you can connect up to pin 13 (VDD) and pin 2 (GND) - you are going to want, at minimum, to connect the ground pin to the Arduino's ground.

If you can solder to the pads or holes (for whatever reason; maybe it is an SMT board), solder to the nearest component that the lead went to (like I noted before, likely a resistor). If it is an SMT PCB, you are going to need a steady hand, a small soldering iron tip, maybe a magnifying glass, and some patience - oh, and smallish diameter hook-up wire (24 AWG may be ok; you might need smaller).

Once you have the wires hooked up, you can test the car by taking a function lead (say the forward function on pin 11), and hooking it to the VDD pin (pin 13) - briefly - to see if the motors do what they should do for that function. If nothing happens, then you have a problem - you either have a short, an open (maybe a cut trace or something?), or maybe the car doesn't work! I can't go into what would be needed to troubleshoot this; it goes beyond the scope of all this.

Once you have all the functions working, you can then take those leads for the five functions (forward, reverse, left, right and turbo), and connect them to the Arduino via the digital output pins (you may or may not want to buffer them; I personally would do so), along with hooking up the ground.

After that, it is coding time - good luck!

:slight_smile: