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Basic Stamp - Javelin compalility — Parallax Forums

Basic Stamp - Javelin compalility

MagnusMagnus Posts: 18
edited 2007-04-12 16:43 in General Discussion
Hello,
I have a strange problem. I have built a small board with a 28pin connector and a radio modem (TRS400 from Low Power Radio Solutions). I have done some programming with the BS2e in the socket and it all works fine, but when I replace the BS2e with my Javelin nothing works.

I can't send or receive using the radio modem. The Javelin outputs the correct signals but its never transmitted or received. If i replace the radio module with a ttl to RS232 converter i can see the data.

So my question is:


Do I need to do anythin with the signal between the Javelin and the modem that i don't hav eto do on the BS2e?

I tried with a pull down resistor (10KOhm) but that didn't change anything.

I want to use my Javelin but i'm getting a bit frustrated now...

/Magnus

Comments

  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2007-04-12 12:30
    Can you post both your basic and your javelin program?
    That way we can see where the javelin code differs from the basic code.

    regards peter
  • MagnusMagnus Posts: 18
    edited 2007-04-12 12:41
    Here's the javelin code:

    import stamp.core.*;

    public class ModemTest {


    final static int radio_TX_PIN = CPU.pin1;
    final static int radio_RX_PIN = CPU.pin2;
    final static int SERIAL_TX_PIN = CPU.pin6;
    final static int SERIAL_RX_PIN = CPU.pin7;
    final static int GPS_RX_PIN = CPU.pin10;

    static Uart GPSUart = new Uart( Uart.dirReceive, GPS_RX_PIN, Uart.dontInvert,
    Uart.speed4800,Uart.stop1 );


    /* static Uart txUart = new Uart( Uart.dirTransmit, SERIAL_TX_PIN,Uart.dontInvert,
    Uart.speed4800,Uart.stop1 );


    static Uart rxUart = new Uart( Uart.dirReceive, SERIAL_RX_PIN, Uart.dontInvert,
    Uart.speed4800,Uart.stop1 );
    */

    static Uart radioTXUart = new Uart( Uart.dirTransmit, radio_TX_PIN,Uart.invert,
    Uart.speed4800,Uart.stop1 );

    static Uart radioRXUart = new Uart( Uart.dirReceive, radio_RX_PIN,Uart.invert,
    Uart.speed4800,Uart.stop1 );

    static char tecken;

    public static void main() {
    radioTXUart.sendString("Hello");
    while (true) {
    if (radioRXUart.byteAvailable()) {
    tecken=(char)radioRXUart.receiveByte();
    System.out.println(tecken);
    }
    else
    {
    System.out.println("No data");
    }
    }
    }



    And some sample working BS2e code


    ' {$STAMP BS2e}
    ' {$PBASIC 2.5}


    n48 CON 188


    main:
    SEROUT 1,n48, [noparse][[/noparse]"$LAD#",CR]
    PAUSE 50
    GOTO main
  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2007-04-12 13:48
    The code looks ok.
    You say, when you replace the radiomodem with a TTL/RS232 converter (max232?)
    then you see (at a PC using a com port?) the data. I have many boards that
    have a max232 and then I always must use Uart.dontInvert to see the data
    at a PC. You specified Uart.invert, which complies with the basic program, but not
    with the fact that you see the data when using a TTL/232 converter.
    Have you tried using Uart.dontInvert?
    Another issue may be the power. The javelin draws considerably more current
    than a BS2E. Can your powersupply deliver 80mA for the javelin plus the current
    required for the radiomodem?

    regards peter
  • MagnusMagnus Posts: 18
    edited 2007-04-12 14:17
    * Radio modem requires Inverted. When i tried with the level converter i changed the code to NotInverted.
    * I use an external 5V source to drive both the modem and the Basic Stamp/Javelin. I actually tried to change 5V supply.

    One clue that leads me to believe that is a level problem is that I sometimes get a lot of rubbish on the receive port. I have tried a 10KOhm pull down resistor, but that makes no difference.

    Is the Javelin more sensitive on the pins?

    /Magnus
  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2007-04-12 14:46
    Javelin pins are cmos compatible (0/5V logic with 2.5V treshold).
    I got the radiomodem manual from here:
    http://www.lprs.co.uk/pdf_directory/11314mylprs1155820109erx00-02-series-data-sheet-(rev-2.4).pdf

    It states that some baudrates may require 2 stopbits.
    Have you tried using Uart.stop2?
    Since the BS2e excecutes code from eeprom, 1 stopbit may be sufficient for BS2e.
    The javelin executes code from parallel sram so maybe 2 stopbits are necessary.
    Increasing the stopbits decreases the pace at which characters are sent.
    For the receive uart I would still use 1 stopbit.


    regards peter
  • MagnusMagnus Posts: 18
    edited 2007-04-12 15:49
    Thank you for your efforts.
    No luck with 2 stop bits. The problem is that as soon as i start transmitting bytes, I start to receive Smile on the receiving pin.

    The thing is that i have used the Javelin with this radio module about a year ago, but i can't find the source code i used back then.

    I think this is a questin for the support att LPRS.

    /Magnus
  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2007-04-12 16:07
    Have you tried another javelin pin for receive?
    Maybe the pin currently used is damaged.

    regards peter
  • MagnusMagnus Posts: 18
    edited 2007-04-12 16:43
    No, but sending bytes from the transmit pin to the receive pin works. I got the advice from LPRS to buffer the signals with a 1K resistor in series. I will test that tomorrow...

    I am looking for a longer range radio module. Something with 250mW output power. Any suggestions?

    Regards

    Magnus
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