Serial communication over RF (radio)

search · 2007-12-27 20:36

I am trying to figure out how to program one way serial communication using RF (radio) units from Quasar.

The transmitter module is connected to a Basis Stamp 1, and I am using SEROUT 7, T600, ("y") to send the character y when I push a button. Here is the TX module: http://www.quasaruk.co.uk/acatalog/FM_Transmitter_Module.html

The receiver module is connected to a Javelin Stamp. The data pin on the RX is connected directly to the rxUart pin on the Javelin. Here is the RX module: http://www.quasaruk.co.uk/acatalog/FM_Receiver_Module.html

I have a audio radio listening on the RX frequency and there is something transmitted over the air when I push the button, but the rxUart on the Javelin does not receive anything. BUT, if I turn the transmitter off completely, the rxUart starts receiving (random?) data.

I just dont know what to do. Do any of you have any tips for me?

Peter Verkaik · 2007-12-27 21:05

Can you post some code?

regards peter

search · 2007-12-27 21:18

Here is the source code I have written. bsTX=Basic Stamp+Transmitter jRX=Javelin Stamp+Receiver

bsTX source:

' {$STAMP BS1}
' {$PBASIC 1.0}

' BS1 TXC V2.1 Card


Setup:
  DEBUG "Setup start"
  INPUT   0 ' Button pin
  OUTPUT  6 ' LED pin


Main:
  IF PIN0 = 0 THEN SendData ' If button is pressed. Pin0 turns low when button is pressed
  PAUSE 100
GOTO Main


SendData:
  GOSUB FlashLED
  GOSUB SOut
GOTO Main


FlashLED:
  PIN6 = 1    ' LED on
  PAUSE 100
  PIN6 = 0    ' LED off
  PAUSE 100
RETURN

SOut:
  SEROUT 7, T600, ("y")
  PAUSE 1000
RETURN

jRX source:

import stamp.core.*;

public class JavRX2 {
  final static int SERIAL_RX_PIN = CPU.pin0;

  static Uart rxUart = new Uart ( Uart.dirReceive, SERIAL_RX_PIN, Uart.invert,
                                Uart.speed600, Uart.stop1 );

  static StringBuffer buffer = new StringBuffer(128);
  static char c;
  static boolean a=true;

  static void bufferMessage(){
    c = 0xff;
    while (c != '\r') {
      if (rxUart.byteAvailable()){
        c = (char)rxUart.receiveByte();
        buffer.append(c);
      } // END if
    } // END while
  } // END buffer message

  public static void main(){
  System.out.println("Ready");
    do{
      buffer.clear();
      bufferMessage();
      System.out.println("Test");
      c = (char) rxUart.receiveByte();
      System.out.println("Byte received");
    } while (a==true); //(c == 'y' || c != 'n'); // END do
    System.out.println("Goodbye!");
  } // END main
} // END public class

Peter Verkaik · 2007-12-27 21:31

You just send "y" so why do you expect to receive '\r' ???
BufferMessage can never exit if it does not receive '\r'

Try this:

··public·static·void·main(){
··System.out.println("Ready");
····do{
······//buffer.clear();
······//bufferMessage();
······//System.out.println("Test");
······c·=·(char)·rxUart.receiveByte();
······System.out.print(c); //this should display all "y"
····}·while·(a==true);·//(c·==·'y'·||·c·!=·'n');·//·END·do
····System.out.println("Goodbye!");
··}·//·END·main

Also, are you sure the javelin receives inverted data? Have you tried Uart.dontInvert?

regards peter

search · 2007-12-27 21:58

Thanks Peter.

Your code worked and I am actually receiving the text I am sending over the radio now!

The System.out.print(c); shows some weird characters instead of what I am sending, but I get the same weird characters every time, so it is actually kind of working. Now I know my hardware is ok.

I really dont know if the data is inverted or not, but I think it is inverted, because if i choose dontInvert I get different characters on each button push.

I will work more on my code now.

thanks again.

Serial communication over RF (radio)

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