Help! Automated Car Project

After reading several threads on this forum (http://arduino.cc/forum/index.php?PHPSESSID=70e2c210050fdb685fcb9560d6978ba5&topic=86883.45) and some instructable site links I thought it would be interesting to try and build my own automated car!

First all I want the car to be able to do is travel along a path that I program in, (i.e. forward for 5 seconds then turn for 2 then forward). Just nice and easy to start with and if its not too difficult maybe try add some more interesting things into the code. So i bought a cheap rc car from ebay and took it apart and also bought an arduino uno to play with!

Now comes the problem, the chip inside of the car looks nothing like the rx2/tx2 ive seen in any sites (and i must have looked at like 30…). Does this mean ill have to buy a motor shield or something before i can get my car to work?! Here are a bunch of photos of everything, hopefully someone can help.

Can you read the IC’s name on the other side?

It seems the chips have their type numbers sanded off. You should have made a picture with the wires still connected to the pcb (or did you) and put it up on there too. So here's some guessing. The smaller 8 pin chip might be a receiver, but i can't see how the antenna is connected to it (i do see where the antenna is supposed to be). The larger 14 pin chip might be a controller like your Arduino. The 4 transistors on the other side have the motors connected to them would be the "power stage". This power stage is controlled by the 14 pin chip through the transistors that have "LF" printed on them.

MAS3: The smaller 8 pin chip might be a receiver, but i can't see how the antenna is connected to it (i do see where the antenna is supposed to be). The larger 14 pin chip might be a controller like your Arduino. The 4 transistors on the other side have the motors connected to them would be the "power stage". This power stage is controlled by the 14 pin chip through the transistors that have "LF" printed on them.

I'd agree with that. Pins 1 and 14 on the 14 pin SOIC look like left and right (or vice versa) and 12 and 13 are forward/reverse. Stick some wires on those four pins and hook them into four PWM-capable pins on the arduino and go nuts.

Chagrin: I'd agree with that. Pins 1 and 14 on the 14 pin SOIC look like left and right (or vice versa) and 12 and 13 are forward/reverse. Stick some wires on those four pins and hook them into four PWM-capable pins on the arduino and go nuts.

I think you're right on the forward/reverse pins - but I'm not sure about the left/right part - it seems like pins 2 and 3 could also be something; maybe if OP could tell us which holes the wires to the motors were connected to, it would be easier to figure out.

That 14 pin chip is definitely the controller, though - analogous to the RX2 half of the TX2/RX2 chipset; I'd be very curious as to what it was originally marked, so I could get a datasheet on it.

Regardless - you still will want to try to identify what the voltage level outputs are of the chip, if possible, once the proper output pins are found. Because if it is outputing 3 volts or less, and you put the Arduino on at 5 volts, you could blow those SMT transistors.

cio74: Can you read the IC's name on the other side?

The 14pin SOIC? Literally has no writing on it just a small dot in the right hand corner. The Numbers 8133-RX REV-01 are near where the antenna was.

MAS3: You should have made a picture with the wires still connected to the pcb (or did you) and put it up on there too.

Unfortunately i didnt think of this i just got excited and cut all the wires..

The left and right was controlled by a similar motor as the forward and reverse it was just mounted sideways with a gear. So i assume it would be connected in much the same way as the forward/reverse motor.

Chagrin: I'd agree with that. Pins 1 and 14 on the 14 pin SOIC look like left and right (or vice versa) and 12 and 13 are forward/reverse. Stick some wires on those four pins and hook them into four PWM-capable pins on the arduino and go nuts.

Ill give this a go later tonight and see how I do and also will try and remember where the wires were originally.

Peter_Ross: The left and right was controlled by a similar motor as the forward and reverse it was just mounted sideways with a gear. So i assume it would be connected in much the same way as the forward/reverse motor.

Consider it a lesson learned: When doing any kind of reverse engineering, you always need to make copious notes, take tons of pictures (before and after any changes), keep them all in order (very important), and label wires, etc. In fact, it would've been best had you cut the wires to the motors and battery, instead of desoldering them, because then you could easily match colors (and likely polarity, too).

Keep this in mind for the future, and good luck figuring it out!