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IR Communication using PDA (rs232)? — Parallax Forums

IR Communication using PDA (rs232)?

NitrohawkNitrohawk Posts: 17
edited 2007-02-17 20:46 in BASIC Stamp
Bear with me as I attempt to explain my objective regarding IR and my PDA.
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My goal is to make use of my PDA for WiFi connectivity and via IR communicate commands to my BS2.
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The generic set up would be like this:
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SERVER <--(wifi)--> PDA <--(IrDA)--> BS2
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I have done a little research and it sounds like I would need to use something like the MCP2150 to do all of the initial discovery mode as well as the handshake. I would then need to create a three wire serial connection with the MCP2150 from the BS2.
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Here is the datasheet for the MCP2150
http://rocky.digikey.com/WebLib/Microchip/Web%20Data/MCP2150.pdf
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Is this the best method to make use of the BS2 or is there another method that I have over looked?

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Nitrohawk

Comments

  • TiboTibo Posts: 81
    edited 2006-02-07 20:24
    Nitrohawk said...
    Is this the best method to make use of the BS2 or is there another method that I have over looked?
    Well, how about a 'simple' serial link ? It depends on the PDA you have but I did exactly what you want to do with my ipaq h4155 and a serial cable...Therefor adding substancial computing power to my robot. You just need to code a tcp/udp<=>serial proxy software for your PDA. There are plenty of code examples avaible on the net.
    ++
  • allanlane5allanlane5 Posts: 3,815
    edited 2006-02-07 20:38
    IrDA is kind of limited, both in speed (9600 Baud) and distance (< 2 feet).

    The MAX-3100 will support IrDA, and provides an 8-byte buffer, so it will send and recieve data while the BS2 is doing something else -- if you REALLY want to go that route. Requires an external baud-rate crystal. www.PHAnderson.com used to sell both the chip and crystal in single quantities.

    Really, wired RS-232 would be better, if possible.
  • NitrohawkNitrohawk Posts: 17
    edited 2006-02-07 20:50
    I should have added the location of my PDA and its function...

    My PDA will be on the same platform as the BS2, so distance is not an issue.. as a matter of fact, they will be sitting right next to each other.

    The PDA is a Dell Axim X5. I have not really looked into cables for the device, mainly because I want to be able to slip my PDA into the robot and take control without having to fidget with cables.

    allanlane5, you said something about this MAX-3100, Do you have some links or diagrams of this hooked up with the BS2?

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    Nitrohawk
  • allanlane5allanlane5 Posts: 3,815
    edited 2006-02-07 20:57
    Google IS your friend.

    http://www.maxim-ic.com/appnotes.cfm/appnote_number/3025

    Straight from the vendors mouth. Note the BS2 does '3-wire' or "SPI" communication using the SHIFTIN/SHIFTOUT keywords.

    And here's a BS2 app directly:

    http://www.emesystems.com/BS2IrDA.htm

    Oh, and note IR is notorious for being sensitive to sunlight and flourescent lights -- so you might want to 'hide' the link inside a light shield.

    That cable is sounding better and better to me.

    Post Edited (allanlane5) : 2/7/2006 9:00:05 PM GMT
  • NitrohawkNitrohawk Posts: 17
    edited 2006-02-07 21:31
    Thanks guys.

    I will take your suggestions and attempt to implement over the next few days.

    My largest stumbling block was how to get the MAX3100 or the MCP2150 to talk to the BS2. That second link:

    http://www.emesystems.com/BS2IrDA.htm

    put it all together.

    Next is to find out what makes a good IR shield. Tinfoil?

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    0011010000110010

    Nitrohawk
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-02-07 22:05
    Nitrohawk -

    Just take a black Magic Marker to a paper drinking straw, making it opaque, and cut a length that suits your needs.

    Regards,

    Bruce Bates

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  • NitrohawkNitrohawk Posts: 17
    edited 2006-02-07 22:08
    Bruce,

    Thanks for the suggestion.

    I will see if I can make that work!

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    Nitrohawk
  • allanlane5allanlane5 Posts: 3,815
    edited 2006-02-08 14:41
    I guess it's not obvious, but IR is basically "Light". Thus, it can be interfered with by sunlight -- which is a bright light -- and by Flourescent lights -- another bright light, which flickers at 60 Hz.

    This is unlike RF, which is basically 'radio waves'. RF must be blocked with electrical shields, like grounded aluminum foil. IR can be blocked with anything that blocks light -- like a black piece of paper or cardboard.
  • NitrohawkNitrohawk Posts: 17
    edited 2006-02-08 18:03
    Okay.
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    I was under the impression (granted, I have done little actual research) that IR has the ability to penetrate some semi opaque·materials.

    But based on my platform, this really should not be such an issue. I can easly build a shield letting in little to no light (natural or man made).

    Thanks for all of the pointers.

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    0011010000110010

    Nitrohawk
  • Tom WalkerTom Walker Posts: 509
    edited 2006-02-08 18:14
    Nitrohawk,
    You may have been thinking of UV...another kind of light. There are materials that one would think would block any kind of "light" that are quite ineffective at blocking UV...even some that appear totally black.

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    Truly Understand the Fundamentals and the Path will be so much easier...
  • JonathanJonathan Posts: 1,023
    edited 2006-02-08 18:54
    Hi All,

    My personal experience is that IR can punch through many opaque plastics. For example, ball point pen bodies. I discovered this while trying to make a replacement for the "eye tube" used on Parallax's SumoBots.

    Just my $.02

    Jonathan

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    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • BipedalBipedal Posts: 5
    edited 2007-02-17 20:46
    Hey,


    If you would like to use the mcp2150 but have no exp with it, Buy a book!LOL
    The book is called PDA Robotics and it depicts the PDA controlling a Pic micro controller but it does have alot of info on connecting a PALM OS PDA OR WIN CE PDA to a robot. The pda connects to vishays tfds4500 IRTrans then the IRTrans connects to the mcp2150. I am currently working on the whole MCP2150 BS2 bot. And it is worth the little bit of study.
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