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UART VP Help — Parallax Forums

UART VP Help

rcarmelrcarmel Posts: 13
edited 2005-07-30 22:36 in General Discussion
I'm having trouble with the uart vps from this site: http://www.sxlist.com/techref/scenix/lib/io/osi2/serial/rs232_sx.htm

I cannot get my sx28 to recieve any data from my pc.· I have no problem however sending information from my sx28 to my pc.

I've tried 5 different vp uarts, and none of them will recieve from my pc, all can send.
I've tried 2 different max232 chips, I've tried 4 different com ports (2 on 2 different computers).· No luck.
I've verified my comports are working with a loopback cable.
I've tried 3 different terminal programs... I'm out of ideas.

If anyone can shed some light on what I might be doing wrong, I'd be ever so thankful.

rcarmel

Comments

  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2005-07-30 10:52
    check your connections!

    sx28 GND to PC comport pin 5.

    sx28 tx to MAX232 TTL input. Corresponding MAX232 RS232 output to PC comport pin 2.

    sx28 rx to MAX232 TTL output. Corresponding MAX232 RS232 input to PC comport pin 3.

    Set PC terminal program to 8 databits, no parity, 1 start, 1 stop, no handshake
    (no handshake is eminent for the PC to transmit data)

    Since you cannot receive data in the SX from the PC, the handshake may not be set to none!

    regards peter
    ·
  • rcarmelrcarmel Posts: 13
    edited 2005-07-30 16:35
    Thanks for the reply.

    I do have the terminal program set to 8N1 and the correct baud, with no handshake (as per the notes in the uart_vp).

    I do have ground connected (as the pc would not have recieved anything if not) and all pin connections are exactly as described in the uart_vp:

    SX | | MAX232 | 9-pin plug
    ; RA.3 -|
    |- T1IN T1OUT -|
    TD
    |-2-|
    SERIAL
    ;·RA.2 -|
    |- T2IN T2OUT -|
    CTS----|-8 |
    PORT
    ; RA.1 -|
    |- R1OUT R1IN -|
    RD
    |-3 |
    ON
    ; RA.0 -|
    |- R2OUT R2IN -|
    RTS----|-7 |
    PC

    rcarmel
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-07-30 16:46
    If you're using the latest version of the SX-Key software you could write a simple test in SX/B (using SEROUT and SERIN) just to see if your connections are working. Once that's sorted you can investigate your VP code.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Jon Williams
    Applications Engineer, Parallax
  • rcarmelrcarmel Posts: 13
    edited 2005-07-30 22:36
    Thanks guys.· I got it working.

    I was misinterpreting my max232 datasheet.· Shame on me.

    Thanks again for your time.

    rcarmel
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