Saturday, February 18, 2012

Control RC Car Transmitter with Arduino

EDIT: RC Car Update

Now that I can trigger buttons with Arduino (a post or two back), I bought a cheapo RC car from Walmart and almost immediately tore it apart :)

The Victim: New Bright RC Corvette


Transmitter:
It contains a NEW BRIGHT T288-2 0726 chip, which some say is just a re-branded TX2c(very common IC for cheap RC), and i would have to agree as the pin out is almost identical and functions the same. The IC encodes the button status(on/off) to a radio signal that the receiver can decode and act accordingly. The buttons function the same as the older remote i was tinkering with in my previous post, so that makes it easier to interface with a Arduino(just a diode to a digital pin). They are +3v when open, 0v when closed. I found it annoying trying to solder a wire directly on to the button pin, but for some reason their were little solder pads on each trace for each button, so i just connected the wires there. This IC, i believe, also has a turbo function, which is normally used for extra features on the car(lights, sound etc) that are non existent on this cheap model. I think ill still solder a button to the IC pin and make a little hole in the remote case to mount it and to utilize this extra pin. Maybe add some headlights to the car?


In this second picture you can see the wires to a header accessible to the outside for the Arduino and the new TURBO button for the car headlights. I put the diodes for triggering the button inside the case for easier interface with the Arduino. I brought out VCC to the header too so that i can power the remote from the Arduino, if necessary. Also, i cut a little hole in the case for mounting the TURBO button.
EDIT: I have found that the turbo button isnt just an extra "channel" it messes with the movement of the car too. With turbo on, the car goes forward and left when i press the left button, same for right too. Forward/Back don't work anymore.




Receiver(car):
It contains a NEW BRIGHT R288-2 0802 chip(again, probably a RX2c clone). not much to explain here... The IC receives the signals, decodes them, then turns on/off the mosfets(L,R,B,F) depending on what data it has received. The wheels use a normal DC motor for turning, not a servo. 5AA batteries at 1.5v, so about 7.5v total, but the IC runs at 3v. Now that i found the TURBO pin on the remote and added a button for it, i can put in another NPN transistor on the car and put some headlights in :)




TX2c_RX2c.pdf is a datasheet for the TX2c and RX2c; the only difference i can find between the NEW BRIGHT IC and the TX/RX2c is that the Left/Right pins are switched, and the Forward/Back pins are switched.

22 comments:

  1. awesome to find this. this is what im working on today. got the pins on the remote currently soldered on. going to use a rj45 jack to plug the arduino in. as for what i'm going to do with it, I figure at least an IR sensor or two for self-navigation, but I might mount a stripped down furby on top with all the sensors it has, should be plenty to work with for my first autonomous robot =] Thanks for this page.

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  2. Thanks for your post! I am doing a similar project but I am using an Arduino with a wifi shield to control the car. Your link to the datasheet is broken and I have had a terrible time trying to find the datasheet. Do you have a different link? Thanks again!

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  3. could you try it now? i changed it.

    thanks

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  4. Works. Actually it is better than the one I found.

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  5. Dear Jordan!

    How did you make the the F/B/R/L pins you made accessible on the remote go to ground with the Arduino? Have you been using some external MOSFET (with a driver IC?)?

    I'm making a project with also a NewBright RC car using the Cypress PSoC 4 pioneer board.
    I solderd the wires to the testponts as You did. I configured a digital output (3,3V) as an open drain output going tow on my uC. It did not switched the "button".

    As you can see i am rather new to electronics+uC and I would very much appreciate your help!
    Yours
    Gergo

    ReplyDelete
    Replies
    1. you use connect the pin to a digital pin with an inline diode. i have a post about triggering buttons here: http://dduino.blogspot.com/2012/02/trigger-buttons-with-arduino.html

      as for code that is in the update post here: http://dduino.blogspot.com/2012/03/rc-car-update.html but specifically the code you need is:
      //activate button
      digitalWrite(PinNum, LOW); // PinNum is the number of the digital pin
      pinMode(PinNum, OUTPUT); // Pull the signal low to activate button

      //releasing
      pinMode(PinNum, INPUT); // Release the button.

      Delete
  6. Jordan,
    Me and a couple of friends are first time Arduino users, as well as first time programmers. Our goal, using the same RC Car, an Arduino Uno R3, and a ,GlobalSat EB-5365RE. Our goal is for this car to drive to way points using Google maps. We are having trouble finding code help. Also, how do we integrate the T288-2 with our Arduino Uno?

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    Replies
    1. what do you need help with in the code? you could trigger the pins like i did on mine or you could wire the arduino into the driver board on the car (latter is probably better since this is gonna be a GPS rover).

      have you looked here? http://dduino.blogspot.com/2012/03/rc-car-update.html or here http://dduino.blogspot.com/2012/02/trigger-buttons-with-arduino.html

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  7. We're having trouble finding code for the GPS Shield. In addition, how can we integrate this with google maps so I can set up way points so the car will know where to go? I'm starting to feel we bit off more than we can chew.

    ReplyDelete
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    ReplyDelete
  9. Hi how can I directly connect the arduino uno into the pins of the receiver board instead of the transmitter/controller board?

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    Replies
    1. you could use the arduino to activate the transistors on the receiver/motor driver board. You'd just have to find the trigger pins on the transistor and connect it to an arduino pin. You'd probably want to disconnect the trigger from where it was going to before as to not create issues.

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  10. hello there, I'm a newbie to Arduino. I work with similar project!
    I need some help, please?

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    Replies
    1. first, Can I power the transmitter via 2 1.5v battery instead of arduino?
      I'm about to connect only the joystick pins(1, 14) to arduino.

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    2. should be able to use two AAs as long you keep the arduino positive separate from the transmitter power, and connect the arduino and transmitter ground together.

      should be good on those pins, but you need the ground as well as mentioned above.

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  11. I have purchased one of these new bright RC cars (blah) for my son, I have set my sights on making this little dud a bit faster. The first idea I had was to change motors, after a little thinking I changed my mind. If I can just increase the power to the rear motor without introducing extra voltage to the main circuit I can get that thing smoking tires (kidding). So without smoking the circuit, what is the best way to do this? Would transistors allow me to add power from a couple extra AA's in series with the current voltage supplied? I assume it switches +/- when it needs to change from forward to reverse it just flips the polarity to the motor causing it to run the opposite direction, is that going to mess up the transistor idea?

    ReplyDelete
    Replies
    1. The radio IC has 6.0v max voltage rating according to the data sheet so im guessing the AAs are fed directly to the circuit with out a voltage regulator. So the way i'd do it would be to use a six AA holder and you can tap off the first four AAs to feed the majority of the circuit through the regular battery terminals and then cut the traces feeding the battery voltage to the mosfets and connect the full voltage from six AAs to the mosfets. let me know how long the motor lasts! :D

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    2. or just add a little two pack AA holder and connect the ground to the positive on the integrated four AA pack and connect the positive to the splice in point to the mosfets.


      That'd be less modifying.

      Delete
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