Question on RF transmitter and RF recevier
Botakhead
Posts: 12
Hi,
I had bought a Basic Stamp, RF transmitter·, RF receiver, LCD and GPS module·from Parallax. I am using them for·my school project. When I downloaded and open the RF transmitter source code by Parallax, I saw that I would need to mount the RF transmitter and RF receiver onto 2 separate Basic Stamp. May I know if I have to buy another Basic Stamp ? As I am a secondary school student, the Basic Stamp is not cheap to me.
I had bought a Basic Stamp, RF transmitter·, RF receiver, LCD and GPS module·from Parallax. I am using them for·my school project. When I downloaded and open the RF transmitter source code by Parallax, I saw that I would need to mount the RF transmitter and RF receiver onto 2 separate Basic Stamp. May I know if I have to buy another Basic Stamp ? As I am a secondary school student, the Basic Stamp is not cheap to me.
Comments
Can you give us a few details of your project?
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Tom Sisk
http://www.siskconsult.com
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I am trying to send the information from the GPS module to show on the LCD. The GPS module will be mounted with the RF transmitter on a Basic Stamp.The LCD will be with the RF receiver. The Baisc Stamp with the GPS module will be on mobile and information will be sent to the LCD. And 1 more question. Does the RF transmittor and RF receiver reqiure programming ? When sending the information to the LCD, can i mount everything on 1 Basic Stamp.
1 Baisc stamp cost about SGD $2xx in my state(Singapore).
You will need a Stamp on the receiving end (as well as one on the transmitting end). Something has to take the data received by the RF receiver, recognize valid data, break it into pieces representing the information you want to display, format it, and send it to the display. What you're describing can be done: I set up two BS2s to do this last fall. But it will require two Stamps.
An engineer might be able to build a non-microprocessor-based way to receive and display the information, but it'd be quite a feat, and I'll bet it wouldn't cost much less than a Stamp.
As for you question about whether the RF units "require programming", the Stamps that you connect to them will need to be programmed to send and receive the information. The units themselves are not programmable - they just do what the Stamp tells them to do.
Post Edited (sylvie369) : 10/22/2008 1:12:54 PM GMT
I haven't ever done it this way however, and it assumes that the LCD is a serial type, not parallel.
Jonathan
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www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
Oh i see. Is the programming on the RF transmitter and RF recevier difficult ? I found it hard to understand. I tried to read from the Basic Stamp manual and read from other posts from the forum. But I could not understand them as this is the first time I seen Basic Stamp programming. Could someone show me some example on programming the RF transmitter and RF receiver to send information to LCD please ? I could not understand source code from Parallax download
And my teacher also ask me to find out what is uses of MAX232.
The RF Transmitter and RF Receiver themselves are not programmed. They are simply handling the RF communication, which is done serially. However, as with most RF systems you have noise issues to worry about which can garble or lose data. Without a BASIC Stamp on both ends handling the data, it is likely your display would quickly get too much garbage for you to read. Example RF Transmitter/Receiver code for the BASIC Stamp are available from our website on the product pages. These examples include error checking to ensue data integrity.
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Chris Savage
Parallax Engineering
Basically, your project will be divided into Three distinct parts:
1. Get the wireless receiver to to successfully receive data from the wireless transmitter. Start with the sample programs with the wireless units or in "Whats a Microcontroller" or "Stampworks". One Stamp will use SEROUT to send to the transmitter and the second will use SERIN to receive the data from the receiver.
2. The mobile part with a Stamp, GPS receiver and the wireless transmitter. Get the stamp to successfully read the GPS and display the data using the DEBUG screen. The GPS will be read using the SERIN command. Once the data is being received, use the SEROUT command to send the data to the transmitter.
3. The third part will be the stationary Stamp with the wireless receiver and the LCD. Read the data using SERIN and display the data (after formatting) by using SEROUT to the LCD. (hopefully you've got a serial LCD because they are much easier to use).
The MAX232 (and MAX233) are special chips to shift the Stamp's serial voltages from 0 and 5 volts to +/- 10 volts or so. You shouldn't need them on this project.
Your teacher may let two or more of you do one part of the project each to reduce costs. And, the Stamps can be re-used for many other projects in the future.
Cheers,
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Tom Sisk
http://www.siskconsult.com
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Hope I can complete the project. Thanks guys for helping me
I really need some help cause my teacher is going to review my project in 2 days...
could someone enlighten mi please ? Thanks
You're using a BS2, right (not a BS2px, or anything like that)?
You're using a Serial LCD, right? Like this one?
www.parallax.com/Store/Accessories/Displays/tabid/159/CategoryID/34/List/0/Level/a/ProductID/50/Default.aspx?SortField=ProductName,ProductName
Try this code (from the product page):
' {$STAMP BS2}
TxPin CON 0 ' adjust this to whichever output pin you're using
Baud19200 CON 32
HIGH TxPin ' Set pin high to be a serial port
PAUSE 100 ' Pause for Serial LCD to initialize
SEROUT TxPin, Baud19200, [noparse][[/noparse]"Hello, this text will wrap."]
If it doesn't work, look on the back of your LCD module, and make sure that the two DIP switches are both in the "on" position, to enable communication at 19,200 baud.
I could show the information I want on the LCD from the GPS module if they mounted on 1 Basic Stamp.
Now I'm trying to send the information to another Basic Stamp by using RF transmitter and RF receiver.
Thanks you sylvie369 for trying to help.
I'm using 2 BS2(serial version), a 4x20 LCD backlit, a RF transmitter and a RF receiver for my project. All of them were bought from Parallax
I had attached the code I'm using for review. Hope someone could help me.
Did you run the demo programs for the RF units? If you haven't gotten those to work, you need to figure that out before you try to do it with GPS data and an LCD.
I am not sure how to "put" the demo code into the my Project code so the information from my GPS module could be shown on the LCD.
Should I start writing the RF code in the "Program code" section or at the "Subroutines" section ?
Is the error checking code from the RF units demo code important to my project ? Its is because I dun understand most of it
And I looked at other posts too. May I know what is NMEA sentences ? And how do I put them in my code if It is needed.
I saw this sentence on 1 of the Completed Project section on Parallax forum.
SERIN 1, 188, 4000, NO_DATA, [noparse][[/noparse]WAIT("GPGGA,")
I only pasted part of it cause its too long
I know that GPGGA is NMEA sentence. But I dun know what is the function. And what function is the WAIT command.
I am sorry for asking so many questions. But I'm new to this. Hope someone can help me.
Many thanks
http://home.mira.net/~gnb/gps/nmea.html
You need code to read the GPS. It transmits these NMEA codes: you want to take data from the $GPGGA string that the GPS sends, and read those data into your own variables. Then you want to transmit those variables to your other BS2. Then the other BS2 needs to format them and print them to the LCD.
The "Wait" command tells the BS2 not to start reading data until the correct string ("GPGGA") is sent by the GPS. At that point you can start counting bytes received to figure out which of the incoming data represents which part of the GPS information (Latitude, Longitude, etc.).
The RF code for the transmitter goes in your program after you've read the GPS data.
The RF code for the receiver goes at the beginning, before you're trying to send things out to the LCD.
If I were you, I'd sketch out what needs to be done in what order before I worried about code specifics.
I know it got to do with the error checking code. May I know is it all error checking code the same ? Can I use the error checking code from the RF transmitter or RF receiver provided by Parallax web page for my project ?
Thanks
Attach the code you are using for both sides to your next post so we can see where you are now.
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- Stephen
thanks, david
I think this the link for the RF transmitter and recevier sample code. Email Chris for the page if I'm wrong
The sample programs to which Chris made reference are attached to this message.
Regards,
Bruce Bates
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When all else fails, try inserting a new battery.
Sorry for the late posting of my Transmitter and Receiver code. I tried to follow what Stamptrol had replied previously. However, I could not get the correct value from the GPS module(example Number of Satellite : 1023). I had attached my codes for review. Greatly appreciate if someone could help. Thanks you.
Best regards
BotakHead
In particular, the Number of Sats is a byte value in the code and you report it being 1023!
Is the GPS unit properly powered and does it have a clear view of the sky?
You may have to attach some schematics to refresh us as to where you are in the project.
Cheers,
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Tom Sisk
http://www.siskconsult.com
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The problem is I cant get the GPS value wireless when I send them through 433mhz transmitter and 433 mhz receiver. I had mounted the transmitter and GPS module on 1 Basic Stamp, while receiver with the LCD on another Basic Stamp.