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Reverse Engineering Project — Parallax Forums

Reverse Engineering Project

Aaron WallAaron Wall Posts: 31
edited 2007-11-22 23:35 in BASIC Stamp
So I would really like to be able to use the head mounted display used in various systems by the company SportVue. http://www.sportvue.com/store/product.php?pid=14


product14_1.jpg

This system has 2 parts. One is a unit on the motorcycle that measures gear position, speed and rpm. That module then transmits that information to a small display on the helmet.

From the description of the item, it uses 2.4ghz wireless serial communication.
For my project, I have no need for wireless. But if it would be easier to simulate the wireless signal than to tap into the unit between the antenna and controller, that would be fine.

-Would it be possible to read the rf signals being sent by the transmitter and then recreate them with a Basic Stamp?
-Or scope the serial data after it has been received by the display?
-Or directly control each segment of the display with it's own pin?

Comments

  • steve_bsteve_b Posts: 1,563
    edited 2007-11-20 17:36
    I'd recommend wireless, although you may want to prototype with wired (something about falling off a bike with a wire attached to my brain bucket...).

    Parallax sells some bluetooth modules that should work for your application.
    IF you have a unit to "tap" off of, why not just use that unit? Or are there other things you want to put in there?

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    <FONT>Steve



    What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
    Lee Travino after the second time being hit by lightning!
  • Aaron WallAaron Wall Posts: 31
    edited 2007-11-20 18:08
    The system already exists. I just wanted to use it for a new application. My original plan was to replace the sending unit with a Basic stamp. The problem with this is that it requires me to decode the serial communication between the modules.

    I think what I will do instead is leave the transmitter and receiver system in tact, then simulate the input signals to the transmitter with a Basic Stamp. The cool thing about that method is that I will be able to swap the system between the motorcycle and the snowboard easily.

    The hard part will be simulating multiple signals at the same time. I fear I may need a separate stamp for each signal.

    Does anyone know a good way to simulate more than one constant PWM signal with a single stamp?
    Would be nice if the signal was constant, and I just had to update the value being created whenever the stamp had new sensor input.
  • steve_bsteve_b Posts: 1,563
    edited 2007-11-20 18:23
    Check the parallax site for PWMpal...it'll be under the motor control section.
    Basically you send a command to this unit to have a stepper hold a position...this unit constantly outputs this PWM signal until you send it another one.

    How will you measure speed on your snowboard? Anemometer or paddle-wheel?

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    <FONT>Steve



    What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
    Lee Travino after the second time being hit by lightning!
  • Aaron WallAaron Wall Posts: 31
    edited 2007-11-20 18:36
    No, I was thinking GPS. I can calculate speed, elevation and direction with it.
  • steve_bsteve_b Posts: 1,563
    edited 2007-11-20 19:55
    Sorry about that....I read it as you wanted to simulate voltage signals from sensors.

    For multiple serial streams, the stamp is a single minded creature (although a workhorse) so can only do one thing at a time.
    Same with the SX, although at a much higher speed, a savvy programmer might make it look otherwise.
    Then comes Parallax's new silver fish...the Propellor. It has the equivalent of 8 separate microprocessors onboard with a shared memory area (someone will correct me if I'm wrong). That means you could have each cog running a serial UART that's capable of sharing data.

    I wouldn't say it's for the beginner programmer (I'm still working up the courage) but of course there's lots of support on the forum...also, there's some literature on the horizon that might make learning a bit easier....

    cheers

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    <FONT>Steve



    What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
    Lee Travino after the second time being hit by lightning!
  • Aaron WallAaron Wall Posts: 31
    edited 2007-11-20 20:31
    I will need to do some experimenting with the way the transmitter reads its signals. The wheel speed sensor is a hall effect sensor and the rpm is either a ignition system tachometer signal or a inductive spark indicator. Both will be pure on/off signals. If the MSU (motorcycle sending unit) looks at the on time of it's sensors, I should be able to simulate that with a PWM motor controller.

    If the MSU looks at the frequency of it's sensor signals, simulating them will be a bit harder.
    Do you know of a device like the motor controllers that will output a frequency signal instead of a PWM signal?
  • steve_bsteve_b Posts: 1,563
    edited 2007-11-21 20:20
    The BS2 has a FREQOUT (Not FREAKOUT) command.

    If you are moving to an SX or Prop there must be similar ways of doing the same. (isn't it really just about turning a pin on and off at a certain rate).

    I suggest you install the various programming softwares (as they are free to download) and check the help files.

    cheers

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    <FONT>Steve



    What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
    Lee Travino after the second time being hit by lightning!
  • Aaron WallAaron Wall Posts: 31
    edited 2007-11-22 00:04
    Yeah, I've used that one before. But I still run into the problem of only being able to produce one signal at a time. And I can't continue on with my code without ending the frequency generation.

    I will defiantly be using that command for analyzing the transmitter module to see how it reads. Between that and the PWM command, I should be able to recreate the signals. Then it's just a matter of finding out how to simulate more than once and keep them going while my Stamp takes care of other tasks.

    I think the product called SoundPAL may be what i need. It is a device similar to the PWMPAL, but is used to continuously output a specified frequency. It's made for sound generation, but I think it may work. If my system needs to simulate frequency, I think I will give one a try.
  • steve_bsteve_b Posts: 1,563
    edited 2007-11-22 23:35
    Sounds good!

    you could also move to an SX (at less $ per unit) you could use multiple ones.

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    <FONT>Steve



    What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
    Lee Travino after the second time being hit by lightning!
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