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transmit a value via RF transmitter to a PC — Parallax Forums

transmit a value via RF transmitter to a PC

dspeerdspeer Posts: 7
edited 2006-04-12 15:17 in BASIC Stamp
I have just started learning about the Stamp. For a project I need to be able to transmit a value via RF transmitter to a PC, do a database lookup and send another value back.

I am a complete beginner and have trouble finding anything about this. I imagine there will be a second stamp with a receiver connected via serial cable, but then how do I go from Serial input to database or even text file? There must be literature out there, but I can't find any.

Thanks in advance!

d.

Post Edited By Moderator (Chris Savage (Parallax)) : 4/11/2006 7:37:56 PM GMT

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-04-11 19:47
    On the PC Side you can connect the receiver to a serial port through a driver if it's one of out TTL level devices.· If you're using the EB500 there is a PC adapter (EB600).· In any event data is transmitted serially and you would need an application on the PC side expecting this data on the Serial Port.· Two such programs are linked below.

    http://www.parallax.com/html_pages/downloads/software/software_stampDAQ.asp

    http://www.parallax.com/html_pages/downloads/software/stamp_plot_pro_info.asp

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Ken PierceKen Pierce Posts: 5
    edited 2006-04-12 05:48
    I'm in the same boat. Completely new to this but need to develop a similar device that can transmit a few data values to a pc, query a database, receive a few values and repeat. Basically a datalogging task. Any further info on this topic would be much appreciated.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-04-12 14:26
    Ken,

    ·· What other information did you need?· The basics for doing this are listed above.· The BASIC Stamp can transmit through the EB500 or our RF Transmitter using standard Serial protocol (SEROUT).· The only consideration is getting the signal into the PC, in which in that case the EB500 has the EB600 adapter and our receiver would require a driver, such as the MAX232 to convert the TTL level serial to RS-232 level serial.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • JonathanJonathan Posts: 1,023
    edited 2006-04-12 15:17
    Hi All,

    Choosing an RF link has some considerations depending on the application, like range, complexity of data, and what happens if you get bad data.

    Simple RF links like the 433mHz transmitter can work quite well. However, you have to take care to check and verify the data. This can be as simple as a checksum, or considerably more complex. I have a temp/humidity sensor located near the range limit of the transmitter in my garden. Depending on weather conditions, it can occasionally get spoofed, and I get false data on the other end, which displays on an LCD in my house. To combat this problem, I use a simple checksum. It's easy, because the data is simple, just a couple of bytes. If the data is bad, it is discarded until it makes sense, and the LCD just displays the last reading.

    On the hydrogen powered robot, we use an EB500. This unit takes care of all data checking. Put the data in one side, and the correct data comes out the other side, to the limit of it's range. I have never seen bad data from the EB500, it just quits when you get out of range. For the robot, this is great as I don't ever want it out of control and I send a lot of complex data back and forth.

    With the EB500 it isn't required to use another EB500 mounted on a EB600 to talk to the PC. A bluetooth dongle like the Linksys USBBT100 works well and is much cheaper.

    Jonathan

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    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
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