Hi,
I'm attempting to connect my arduino Duemilanove to a toy rc car. I'm trying to bypass the radio controller and control the toy car's motor directly using the arduino but opening the car up (looks like this ImageShack - Best place for all of your image hosting and image sharing needs ) there is one main circuit board and from there, several cables go to the motor for the rear wheels and front wheels. What I'm trying to figure out now is what these cables do. I've gotten a multimeter and have isolated how to make the back wheels turn using the arduino since its only 2 cables but the front one has 8. Some of the these cable pairs seem to turn "on" when the front wheels turn left or right. Is there any way to figure out what all these cables do? I've tried to look for the schematic (looks like this ImageShack - Best place for all of your image hosting and image sharing needs ) but I can't seem to find any. Does this look familiar to anyone?
I'm not sure of your specific setup in the car- but those lines control either a servo motor or a stepper motor (most likely servo) and possibly provide a signal from an encoder. Are you sure all of those lines attach to a motor? I'm thinking there may be a few lights or whatever on the car... servos usually only need 3 wires, and an encoder would only add two more- and it's also unlikely there's more than one servo for steering.. so that's a lot of pins unaccounted for...
Hi,
Although I can't open the gearbox and motor compartment without breaking it (I'm still trying to figure out how to open it without breaking it), but using a multimeter, when the car is off, the 8 wires from the motor, only 1 pair is connected to each other. I'm sure there aren't any lights or anything but i'm not sure if all the wires are being used. I think its a DC motor with some extra circuits at the gearbox because the shape of the front and rear gearboxes are similar..and the back one is a dc motor. Does the circuit look familiar in any way? If it helps, the IC on the receiver says RX-2-G.
Also, I forgot to mention that near the front gearbox (the one that has 8 wires going into it), there is an adjuster to adjust the front wheels steering and alignment of the wheels left and right..i think it is a potentiometer because it looks like a knob of sorts, but using the multimeter, I can't find where this pot. is located.
Hi,
Maybe I was too ambitious trying to decipher what these cables mean, so I'm going to try something different if anyone can help me:
I have the radio receiver of the car (and its circuit in the first post's picture) and I was thinking of somehow removing the IC of the receiver and replacing it with the arduino...or maybe something simpler like bypass the antenae parts of the circuit and replace it with signals from the arduino...I've been looking around and I think the receiver schematic is something like this:
http://www.silan.com.cn/english/product/pdf/TX-2C(RX-2C)AY.pdf
That uses a RX-2-C but mine is RX-2-G...not sure if that is a significant difference. Thanks again if anyone can help me with this
You need to get into the real hacking mindset. Never give up, never surrender - until the thing is a smoking heap of molten plastic. Then you'll know that the control line didn't use 5000 V to drive the servo.
First test: Make the lines individually interruptible and check what stops working if you unhook them one by one. That will give you some ideas about functions and should allow you identify the ground and power lines.
After that, check what happen on the individual lines - first measure the current and voltage on each, then if they seem to be control lines between 0 and 5 V check what you see on them. That's easiest with an oscilloscope, but you can write yourself a few special purpose programs on your Arduino to validate various theories.
If you have more data, please keep us posted. Perhaps some of us can give you useful pointers - and it's entertaining to read anyway.
Korman
Are you sure you don't want to use arduino to control the remote control? That seems easier and has more possibilities, well unless you want to mount sensors on the car.
Yes, the car has other things controlled by the arduino (webcams motors, robotic arms, sensors, etc), so the point is to get the arduino on the car and maybe i can salvage the radio transmitter and receiver for something else.
But i've tried measuring things. The motor (yes, they are DC motors coupled with a couple of capacitors..I think this is some sort of fault protection or somethin) run on 9V of AA batteries. The receiver also uses this battery pack to receive stuff.
Also, it seems that i've made a mistake...there is only 7 wires going to the front motor...two actually physically go into the motor and the 5 go into this wierd gearbox that has all sorts of contacts....I was unable to open this gearbox to see whats actually going on in it and what the contacts do in it. I also found out that what looks like potentiometer from the outside is actually some simple adjuster and nothing electrical going on in it at all. I can tell that using a multimeter that when the front wheel tries to turn left too far until it can't turn (or right), certain wires goes "on"..but this leaves 1 wire unaccounted for...I'm tempted to just ignore this and hopefully nothing will break when the car tries to run.
Also, is it simpler to hack the transmitter instead of the receiver? I could just place the transmitter on the car itself (yes, its abit wasteful but i'll do this if nothing else works).
Okay, I just had a look at the transmitter, the car's left-right and front-back are just a 3-way contact each..there is no potentiometer to determine how much to turn or anything, just a switch to indicate which way to move.
Traltixx> the wires on the front wheels motor, and position sensing wires(kinda like a servo) use the servo control project and sketch from the code library to control steering, I suggest modifying a motor control shield with a servo control edition. As far as the sketch to make it work, I'm...uh...er...um still working on that one. anyone in the forum got any ideas for the sketch?