Shop OBEX P1 Docs P2 Docs Learn Events
Controlling a radio controlled car??? — Parallax Forums

Controlling a radio controlled car???

neotericneoteric Posts: 144
edited 2006-03-24 14:10 in General Discussion
Is there an add on available that will let a basic stamp control a standard radio controlled car such as would be sold at Radio Shack.· It seems like I have seen some applications, but cannot seem to find any examples of hardware to do such a thing.

Thanks.

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-03-22 18:35
    Interfacing to such devices varies with the particular device.· Some have logic level control signals while others do not.· You would really need to assess the individual product to see how it works, what voltages it uses, etc.· Then you can decide how to interface it to a BASIC Stamp.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Jeff DegeJeff Dege Posts: 85
    edited 2006-03-22 19:18
    There's a book out, "123 PIC Microcontroller Experiments for the Evil Genius", by Myke Predko, that explains how to hack Radio Shack's ZipZap RC cars.

    Yes, he's using PICs, instead of Basic Stamps.

    And it's not a well-put-together book. It's not well organized and it desperately needed the services of a decent copyeditor.

    But it might give you a start on how to interface with the things.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-03-22 21:28
    The Zip-Zaps are probably pretty easy.· What I have found in dissecting R/C Cars from Wal-Mart, K-Mart, Radio Shack, etc. is that sometimes they have discrete transistor or FET control circuits connected to some blob on the board (The controller) which makes it difficult to determine what signals control the higher power circuitry.··If everything used a standard R/C receiver we'd have it made.· In rare cases I have seen Relays controlling the motors (On two R/C tanks).

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • bushibushi Posts: 12
    edited 2006-03-23 06:21
    Here's a schematic I put together this evening detailing a controller I built several years ago. The schematic is a little rough since I'm still getting a handle on the software.

    The car was from Radio Shack and was very basic. The hand-held part had only four buttons, left, right, forward and reverse. I used a SBC called a SIM-1 which had a 6502 microprocessor and 4K of ram (I think that 4K is right). I wired lines from the car controller's switches to a prototype board. The lines where connected to four opto-couplers that interfaced to a parallel port on the SBC. There was software in the SBC that could record and play back the button settings. When the software was running, it would look at the input lines every 1/10th of a second and save the current button settings. That let me record the buttons as I ran the car around the room. To re-play the recorded pattern, I had four small relays connected the the SBC's parallel port and wired across the switches of the hand-held controller. The software in the SBC would look at the saved button settings and set the relays every 1/10th of a second.

    It actually worked pretty well. The where a couple of problems though. The apartment I lived in at the time had hardwood floors. When the car would take-off there was so much torque that the tires would sometimes slip and throw the car off the intended track. The car had occasional collisions with table legs and the like as a result. The second problem was with the car itself. For some reason the receiver in the car could pick-up transmissions from taxi cabs. If one was close enough while the car was powered-up the front wheels would jiggle rapidly back and forth. It looked like the poor thing was having a seizure!

    Hope this gives you some ideas about building your own controller. BTW be careful of the schematic. I can't guarantee 100% accuracy since I did it just from memory and the project was built 10-12 years ago.

    Good Luck!
    RCCarController.jpg
    714 x 910 - 127K
  • Paul Sr.Paul Sr. Posts: 435
    edited 2006-03-23 12:49
    bushi said...
    Here's a schematic I put together this evening detailing a controller I built several years ago. The schematic is a little rough since I'm still getting a handle on the software.

    The car was from Radio Shack and was very basic. The hand-held part had only four buttons, left, right, forward and reverse. I used a SBC called a SIM-1 which had a 6502 microprocessor and 4K of ram (I think that 4K is right). I wired lines from the car controller's switches to a prototype board. The lines where connected to four opto-couplers that interfaced to a parallel port on the SBC. There was software in the SBC that could record and play back the button settings. When the software was running, it would look at the input lines every 1/10th of a second and save the current button settings. That let me record the buttons as I ran the car around the room. To re-play the recorded pattern, I had four small relays connected the the SBC's parallel port and wired across the switches of the hand-held controller. The software in the SBC would look at the saved button settings and set the relays every 1/10th of a second.

    It actually worked pretty well. The where a couple of problems though. The apartment I lived in at the time had hardwood floors. When the car would take-off there was so much torque that the tires would sometimes slip and throw the car off the intended track. The car had occasional collisions with table legs and the like as a result. The second problem was with the car itself. For some reason the receiver in the car could pick-up transmissions from taxi cabs. If one was close enough while the car was powered-up the front wheels would jiggle rapidly back and forth. It looked like the poor thing was having a seizure!

    Hope this gives you some ideas about building your own controller. BTW be careful of the schematic. I can't guarantee 100% accuracy since I did it just from memory and the project was built 10-12 years ago.

    Good Luck!

    Crazy as it may sound, do you by chance have the code you wrote for this laying around (yes, I do have a Sim-1).

    TIA,
    Paul
  • neotericneoteric Posts: 144
    edited 2006-03-23 15:18
    Bushi,

    Thank you very much.· This was the type of information I was looking for.·· So in theory, what I might do, is modify the RC controller.· It is the standard forward & reverse trigger, with steering wheel on it.·· I have purchased a few RC items in the last few years, and all the controllers were the same.·· Interesting approach you took.·· Although I am a beginner, I may be able to figure it out.

    Seems like there would be programmable RC controllers out there somewhere, or RC controllers that have serial ports on them, or something like that.· I can't believe I am the first person to try to do this with a Stamp.



    Thanks all for the help....
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-03-23 16:02
    Chris is not kidding 'about some blob on the board'.· These R/C cars are massed produced in Asia and they get pretty sloppy.·· The boards can be quite ugly and messy.·As long as it functions, it goes into use.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • bushibushi Posts: 12
    edited 2006-03-23 23:18
    @neoteric - I split out one of the switch circuits so it would be easier to follow. I also noticed later on that I had omitted the driver transistor and relay coil diode so I included them in this schematic. Anytime you use relays in circuits like this one you want to have a protection diode in place or you run the risk of frying the circuit when the coil is de-energized.

    @pwssr - Sorry but I don't have the code for this anymore. It was all in hand-assembled machine code too. At one point I had two SYM-1s (misspelled it earlier) but somewhere along the line I misplaced them. Hang on to the SYM-1 you've got since the only ones I've been able to locate are in private collections and museums. They've really become a collector's item.
    RCCarControllerV2.jpg
    513 x 359 - 51K
  • Paul Sr.Paul Sr. Posts: 435
    edited 2006-03-24 13:38
    bushi said...
    @pwssr - Sorry but I don't have the code for this anymore. It was all in hand-assembled machine code too. At one point I had two SYM-1s (misspelled it earlier) but somewhere along the line I misplaced them. Hang on to the SYM-1 you've got since the only ones I've been able to locate are in private collections and museums. They've really become a collector's item.

    It was worth a shot! Yes, I noticed somewhere that the SYM-1 was potentially becoming collectable - who knew! Mine is still in the original box - and I have all of the programs on casettes - which I will probably never be able to read again!

    Thanks!
  • Russ FergusonRuss Ferguson Posts: 206
    edited 2006-03-24 14:10
    The guys at Seattle Robotics have an article about putting a BS2OEM on a cheap radio control platform:
    http://www.seattlerobotics.org/encoder/200008/stakebot.html

    The article is several years old and the radio control toy is not available any more, but you might find it to be interesting reading.

    I·think that·I even·have a couple of the skateboard bases somewhere around here.

    Post Edited (Russ) : 3/24/2006 2:46:23 PM GMT
Sign In or Register to comment.