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Thread: Remote Control Car application query

  1. #1

    Default Remote Control Car application query

    Hi Picaxe,

    I wish to use Picaxe to remote control a car. I wish to create a new controller, and there are several motors on board (please see diagram)

    MVIMG_20180613_141708899.jpg

    I need to use a module to transmit the signal to the car. As you can see from the diagram, Rotary switch 1 operates motors 1 - 4 simultaeneously: one click of the switch moves each motor a fraction, similar to a stepper motor, but without the accuracy. Reversing the rotary switch reverses the motors.

    Switches 2 and 3 operate a steering mechanism. Each sequential click of switch 2 rotates motor 5 (and possibly 6) one way. The other switch will rotate the other way.

    Switch 4 and 5 operate another motor, though this is similar to the above, though perhaps with limit switches, ie a single pulse will rotate x degrees until the limit switch.

    I hope to use pwm for all these motors.

    1. Can I use one of these? https://goo.gl/QomNQf

    2. How many will I need? (Is this related to 'channels'?)

    I think that's all for now. Any help or thoughts gratefully received!

  2. #2
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    Hi,

    Quote Originally Posted by tarantulataramasalata View Post
    2. How many will I need? (Is this related to 'channels'?)
    You can only use one (pair). They all use the same (434 MHz) radio frequency, so any more will interfere with (or block) each other.

    It is up ti you (the designer/programmer) to devise a method to multiplex (combine) the various motor channels into one radio channel. That might be by repeatedly transmitting a sequence of (servo-style) PWM pulses (which is the way some multi-channel RC model transmitters work) or a sequence of "numbers" such as by serial RS232 data.

    Those are very poor quality transmitter/receivers and will probably give a range of only a few metres. There are far better receivers available, even at low cost, perhaps the RXB6 for OOK / PWM signals, or the HC-12 for serial data.

    Cheers, Alan.

  3. #3

    Default

    Thanks Al, that's very helpful. It is also clear that this is a relatively complex business - I am vaguely surprised that something we take for granted (ie any remote control vehicle thing) is not easier. Hey ho.

    Presumably this bad boy is the preferred gizmo? http://www.picaxe.com/Hardware/Add-o...Receiver-Pair/

    And from what I read, these guys will auto encrypt data for more reliable reception: http://www.picaxe.com/Hardware/Add-o...-Radio-Boards/

    I'm going to read a bit more I think!

  4. #4
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    Hi,

    Encoder/transmitter modules are available, but not normally with as many as 5 channels, and/or with PWM capability (although I'm not clear how you plan to use that).

    Quote Originally Posted by tarantulataramasalata View Post
    And from what I read, these guys will auto encrypt data for more reliable reception:
    Not really encryption just "encoding". However, you don't need a separate encoder for the transmitter because it can be done by the RFOUT command of the PICaxe 14M2 (and above) chips. Similarly the RFIN command could be used in the receiver, but the NKM2401 chip (also available separately) is probably worthwhile here, to avoid the "blocking" whilst the program "listens" for any transmissions.

    Cheers, Alan.

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