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RS232-TTL level shifting — Parallax Forums

RS232-TTL level shifting

ArchiverArchiver Posts: 46,084
edited 2003-12-29 15:29 in General Discussion
Hello All,

Does anyone know if you can connect the DB-9 serial outputs directly
to the Basic Stamp, or am I going to need to go through a level
shifter first. Thanks.

-Dave

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-12-24 20:49
    you certinly can connect them via Sin and Sout. I do t all
    the time as i build my boards to talk to the PC. Look at the
    schematic for a carrier board and you will see.
    --
    Regards

    Dave Evartt
    American Hovercraft
  • ArchiverArchiver Posts: 46,084
    edited 2003-12-24 22:05
    If the connections between your RS-232 source and the Stamp are short,
    you can connect the serial data from the source (i.e., PC) to the Stamp
    through a 22K resistor. Output from the Stamp to the PC can be direct.
    Again, this will usually work if the connections are short. Under other
    conditions, and RS-232/TTL level shifter may be required.

    Happy Holidays.

    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office

    Original Message
    From: nuclearspin2000 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=dcrgZz0cCvbbk-EmlOLA9nn1vUnfxiKCnE4gBaZBOOdD6I2CatMYabeau6mJmK4z9WiPwkBI9ZJv7t5B3DmRzfL3qw]nuclearspin2000@y...[/url
    Sent: Wednesday, December 24, 2003 2:16 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] RS232-TTL level shifting


    Hello All,

    Does anyone know if you can connect the DB-9 serial outputs directly
    to the Basic Stamp, or am I going to need to go through a level
    shifter first. Thanks.

    -Dave


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  • ArchiverArchiver Posts: 46,084
    edited 2003-12-24 22:06
    The Sin and Sout pins on the Stamp module have level-shifting circuitry.


    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office

    Original Message
    From: Dave Evartt [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=EKrM6lEx3FfzWtCu7vtaMz7bzISTX5Rbs4qQGjrHZJ4HS1WtU5uvoZv3BxYmYcD0CHRKaRWqydPSdjFGNufMl3wW]davee@a...[/url
    Sent: Wednesday, December 24, 2003 2:49 PM
    To: basicstamps@yahoogroups.com
    Subject: Re: [noparse][[/noparse]basicstamps] RS232-TTL level shifting


    you certinly can connect them via Sin and Sout. I do t all
    the time as i build my boards to talk to the PC. Look at the
    schematic for a carrier board and you will see.
    --
    Regards

    Dave Evartt
    American Hovercraft

    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
    from the same email address that you subscribed. Text in the Subject
    and Body of the message will be ignored.


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  • ArchiverArchiver Posts: 46,084
    edited 2003-12-25 00:49
    Thanks everyone. I'm building my own programming board and am going
    straight into the Sin and Sout pins which thanks to the advice don't
    require separate level shifting. Best regards.

    -Dave

    --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    <nuclearspin2000@y...> wrote:
    > Hello All,
    >
    > Does anyone know if you can connect the DB-9 serial outputs
    directly
    > to the Basic Stamp, or am I going to need to go through a level
    > shifter first. Thanks.
    >
    > -Dave
  • ArchiverArchiver Posts: 46,084
    edited 2003-12-25 03:43
    Be sure you use the inline caps on the DTR-to-ATN connection as we do in
    our boards.

    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office

    Original Message
    From: nuclearspin2000 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=grhNzCM5UW-e5EZWSbrszlB37BTkMEikKcUx8HLC-qo-gYyGP1OdkUtvGmqjmie-3TfHx5mMmXI6Lfvp06bh76k]nuclearspin2000@y...[/url
    Sent: Wednesday, December 24, 2003 6:49 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Re: RS232-TTL level shifting


    Thanks everyone. I'm building my own programming board and am going
    straight into the Sin and Sout pins which thanks to the advice don't
    require separate level shifting. Best regards.

    -Dave

    --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    <nuclearspin2000@y...> wrote:
    > Hello All,
    >
    > Does anyone know if you can connect the DB-9 serial outputs
    directly
    > to the Basic Stamp, or am I going to need to go through a level
    > shifter first. Thanks.
    >
    > -Dave


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
    from the same email address that you subscribed. Text in the Subject
    and Body of the message will be ignored.


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    To visit your group on the web, go to:
    http://groups.yahoo.com/group/basicstamps/

    To unsubscribe from this group, send an email to:
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    Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/




    This message has been scanned by WebShield. Please report SPAM to
    abuse@p....
  • ArchiverArchiver Posts: 46,084
    edited 2003-12-26 05:41
    Dave,

    If you are doing a PCB, look at plenty of schematics and test on
    bread boards.

    I am going to do a PCB.

    If you are doing a PCB, I would like to exchange info with you. I
    think my schematic is complete, but want to finish testing a circuit.

    Take care,
    Frank


    --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    <nuclearspin2000@y...> wrote:
    > Thanks everyone. I'm building my own programming board and am going
    > straight into the Sin and Sout pins which thanks to the advice
    don't
    > require separate level shifting. Best regards.
    >
    > -Dave
    >
    > --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    > <nuclearspin2000@y...> wrote:
    > > Hello All,
    > >
    > > Does anyone know if you can connect the DB-9 serial outputs
    > directly
    > > to the Basic Stamp, or am I going to need to go through a level
    > > shifter first. Thanks.
    > >
    > > -Dave
  • ArchiverArchiver Posts: 46,084
    edited 2003-12-26 16:32
    Hi Frank,

    I'm not doing a PCB yet but will in the future. I'm just testing a
    design using a standard "solder type" perfboard and making the
    soldered connections on the back with thin wrapping wire. So far
    everything works but I'm waiting on a serial connector so I can hook
    up the programming pins. I'm basically just following the schematics
    from the BOE with a few additions and minor changes to suit my taste.
    Best regards,

    -Dave

    --- In basicstamps@yahoogroups.com, "franksmith512"
    <franksmith512@y...> wrote:
    > Dave,
    >
    > If you are doing a PCB, look at plenty of schematics and test on
    > bread boards.
    >
    > I am going to do a PCB.
    >
    > If you are doing a PCB, I would like to exchange info with you. I
    > think my schematic is complete, but want to finish testing a
    circuit.
    >
    > Take care,
    > Frank
    >
    >
    > --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    > <nuclearspin2000@y...> wrote:
    > > Thanks everyone. I'm building my own programming board and am
    going
    > > straight into the Sin and Sout pins which thanks to the advice
    > don't
    > > require separate level shifting. Best regards.
    > >
    > > -Dave
    > >
    > > --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    > > <nuclearspin2000@y...> wrote:
    > > > Hello All,
    > > >
    > > > Does anyone know if you can connect the DB-9 serial outputs
    > > directly
    > > > to the Basic Stamp, or am I going to need to go through a level
    > > > shifter first. Thanks.
    > > >
    > > > -Dave
  • ArchiverArchiver Posts: 46,084
    edited 2003-12-29 15:29
    This may have been said before, but:
    If you're building your own programming board,
    it needs to loop RTS to DTS, and needs to
    connect DTR to the ATN pin.

    The DTR to ATN connection should be done through
    two capacitors -- look at the schematic of the
    BOE for the circuit.

    The reason for these extra connections is that
    the BS2 IDE looks for the RTS to DTS loopback
    to detect you've got the cable connected.
    It then uses the DTR/ATN connection to reset
    the BS2 before programming.


    --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    <nuclearspin2000@y...> wrote:
    > Thanks everyone. I'm building my own programming board and am going
    > straight into the Sin and Sout pins which thanks to the advice
    don't
    > require separate level shifting. Best regards.
    >
    > -Dave
    >
    > --- In basicstamps@yahoogroups.com, "nuclearspin2000"
    > <nuclearspin2000@y...> wrote:
    > > Hello All,
    > >
    > > Does anyone know if you can connect the DB-9 serial outputs
    > directly
    > > to the Basic Stamp, or am I going to need to go through a level
    > > shifter first. Thanks.
    > >
    > > -Dave
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