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Basic Stamp Application? — Parallax Forums

Basic Stamp Application?

bkirkbkirk Posts: 37
edited 2011-10-03 10:58 in BASIC Stamp
This might sound crazy, but does anyone know if there is an application that you can run on a PC which will process PBASIC code like a Basic Stamp would? Essentially, I want to run a basic program on my PC, and have my PC act like a Basic Stamp in lieu of an actual Basic Stamp.

Comments

  • Jimmy LiebJimmy Lieb Posts: 46
    edited 2011-09-30 19:41
    not that i am aware of, I have looked for something like that, like a virtual machine. possibly for controlled testing? I don't believe there is one out there yet.
  • Mike GreenMike Green Posts: 23,101
    edited 2011-09-30 20:58
    There is a commercial Stamp simulator, but it's not free. See this page.
  • bkirkbkirk Posts: 37
    edited 2011-09-30 21:32
    Yikes. Thanks for pointing that out, however, I suppose I would be better off just buying a second stamp.

    The reason I ask is that I'm trying to make my Basic Stamp Mobo wireless. I have to use a transceiver in the MHz range and with the ability to utilize a really good error checking protocol to ensure clean transmission of the information. Because of this, the Xbee's won't work (mostly because of the GHz range, and also because the X-CTU does not appear to error check), so I've chosen to use the Parallax 433 MHz transceivers. The Parallax transceivers come with a really good example error checking protocol I can use as a base, but I have to have 2 basic stamp microcontrollers to use it (or the VSM program). Hyperterminal is practically worthless, at least with my very limited understanding of how this stuff works. Since I just want the data from my Mobo to go into my PC, it appears I may have to just purchase another Mobo, which will be my PC-Mobo, and debug the communications from my PC-Mobo into my computer via the mini-USB.

    Does that make sense? Or do you have any insight you can offer? Thanks!

    Ben
  • Mike GreenMike Green Posts: 23,101
    edited 2011-10-01 08:00
    Yes, you'd probably be better off buying another Stamp. Unless you're really constrained to use 433MHz instead of 2.4GHz, you'd be better off using the xBees with an Xstick on the PC end. Remember that the xBees do their own internal error checking / retry protocol and "guarantee" correct end-to-end data delivery (that's why there's no explicit error checking in X-CTU).
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2011-10-01 09:18
    Could you use the 900 Mhz XBee versions? Those part numbers start with "XBP09". The range can be quite a bit longer than the 2.4 GHz XBees.

    The error checking on the XBee module is going to be much better and much much much less work than trying to build it from scratch on a Stamp.
  • bkirkbkirk Posts: 37
    edited 2011-10-01 11:06
    Yes, the 900 MHz might work. The reason the GHz won't work is that I need the signal to go through water, and I've been told that only a signal in the MHz or, even better, the KHz range can do this. I'm not sure if there will be a significant difference between the 433 and 900 though, so maybe that is something I can look into. Either way it is about the same amount of extra money.

    Regarding the Xbees Mike, I was using the 2.4GHz Xbees previously, I still have 2 of them now actually, but I received considerable interference when I attempted to use them with the X-CTU. Maybe I didn't have my code on the Mobo side written the best to prevent errors, though. I didn't work with them much after I realized they wouldn't penetrate water.

    Thanks for your help!
  • Mike GreenMike Green Posts: 23,101
    edited 2011-10-01 11:46
    You're going to have problems with any of the higher frequencies trying to get a signal through water. 2.4GHz is particularly difficult because there's a particular water absorption frequency in that range. That's why microwave ovens are designed for that frequency range.

    Have a look at this article on underwater communications.
  • bkirkbkirk Posts: 37
    edited 2011-10-01 11:57
    Thanks for the article, Mike. By the way, I just noticed you're from Minneapolis. I live right across the river in St. Paul.

    Do you think 433 MHz is low enough for say, 20ft depth in freshwater? I seem to gather it does from the article. I've also been in touch with an amateur RC submarine builder and he seemed to think 433 MHz was low enough for those conditions.
  • Mike GreenMike Green Posts: 23,101
    edited 2011-10-01 12:32
    I don't know. I'd probably go through the charts in the article I mentioned, then look at the detailed specs of the 433MHz transceivers, then try it out in maybe 5ft of water to see how much signal gets out and compare to the figures from the article.
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2011-10-01 14:02
    Not a chance at 900MHz. Look carefully at that article Mike pointed out. It is talking kilo-Hz, and it depends on the salt content of the water. It will also depend on how the wave is "launched". The change in dielectric constant from air to water is going to refract the wave. That is the 27dB loss at the water air interface he talks about. On the 1.8MHz ham band, with assumptions made about transmitter power, bandwidth, signal to noise etc, he comes out with something on the order of 20 meter range in fresh water. With attenuation proportional to the square root of frequency, at 900MHz that reduces to a little less than one meter for a wave launched underwater, although the assumptions about bandwidth and noise would need to be adjusted too. That is the ballpark. I was involved a number of years ago with an antenna that the Navy was installing in northern Michigan for long range, low bit rate communications with submarines. If I remember correctly, it was to operate at near 70 Hz carrier frequency, and there was something about the iron deposits in the rocks that made it suitable for launching the wave.

    Special effects guru Rick Galinson showed off videos of his remote controlled submarine at the Parallax UPEW. I don't recall what frequency he was using, but then again, I don't think he was shooting for depths.
  • bkirkbkirk Posts: 37
    edited 2011-10-01 21:52
    Thanks for the insight guys. I will have to dive (pardon the pun) into the article a little more and see what I can come up with. Hopefully the 433 MHz will cut it because I think it'll be difficult to locate a suitable transceiver in much less than that. Again, I'm looking at 20ft max depth in fresh water only, so hopefully I can sneak it by. Thanks again!
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2011-10-02 22:14
    Your thread is still marked, "Unsolved". Is this still accurate?
  • bkirkbkirk Posts: 37
    edited 2011-10-03 10:58
    For the most part I think it is solved, and will mark it as so if no one has any final comments on the following issue.

    In reading the article noted by Mike, I am unable to use the attenuation formula Mr. Bulter describes because he does not provide details on computing the conductivity in mhos/meter. He notes that you use TDS, and his sample water has a TDS of 300 mg/liter, however he jumps to a conductivity of 0.0546 mhos/meter without describing how he made the computation. I was able to locate TDS information for the body of water I'm working in, but without knowing how to compute conductivity (or at least how he computed it) I cannot determine attenuation.

    The closest resource I could find was this website: http://www.lenntech.com/calculators/conductivity/tds_engels.htm which has a conductivity calculator. Using this calculator, however, I get a conductivity value much lower than what Mr. Bulter's 300 mg/liter to 0.0546 mhos/meter would suggest is accurate. I thought the discrepancy was from the fact that the conductivity calculator was inputting TDS values at ppm rather than mg/liter, however, from further research into conversion charts (see, http://www.unitconversion.org/unit_converter/concentration-solution.html) I found the difference should only be a small fraction. For example, 300 mg/liter is equal to 300.3426909 in ppm. If this is true, then I can properly use the attenuation formula in Mr. Butler's article, however, his calculations are incorrect. The conductivity of his water sample is not 0.0546 mhos/meter, but is instead 0.00000469 mhos/meter. This would greatly reduce the attenuation value he described, and support the inference that a 1.8 MHz signal would have far less attenuation in his sample of fresh water than 5.4 dB.

    If anyone knows more about TDS mg/liter vs. TDS ppm and computing conductivity in mhos/meter, it would be very helpful to either confirm or correct my conclusions.

    Thank you!

    Ben
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