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Serial connection

ArchiverArchiver Posts: 46,084
edited 2004-03-01 23:02 in General Discussion
I have several questions about serial connection of a device and a
basic stamp through a the 9 pin.

I have a police scanner that can communicate through a serial port at
9600 baud (ajustable) and at 8 data bits.

The one thing I don't know is this whole ttl thing. What is it and
what does it have to do with the stamp/radio.

I do have all of the command protocals for the radio.

Any help would be appreaciated

Duncan Fairley
Djdunkman@h...

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-04-09 00:34
    It turns out the Stamp's programming port (DB9) has a pseudo 232
    driver and reciever built in, so it can be directly connected to
    another 232 device, and communicate with it using SEROUT/SERIN.

    All of its other data pins CAN be used for SEROUT/SERIN, BUT they
    don't have 232 drivers on them, so they will talk/listen at TTL
    levels.

    That 'TTL Levels' phrase means a logic '0' is 0 volts, and a
    logic '1' is 5 volts. These are used instead of the +/- 12 volt (or
    +/- 5 volt) signals used for 232.

    --- In basicstamps@yahoogroups.com, "Duncan Fairley" <Djdunkman@h...>
    wrote:
    > I have several questions about serial connection of a device and a
    > basic stamp through a the 9 pin.
    >
    > I have a police scanner that can communicate through a serial port
    at
    > 9600 baud (ajustable) and at 8 data bits.
    >
    > The one thing I don't know is this whole ttl thing. What is it and
    > what does it have to do with the stamp/radio.
    >
    > I do have all of the command protocals for the radio.
    >
    > Any help would be appreaciated
    >
    > Duncan Fairley
    > Djdunkman@h...
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-01 07:59
    Please help,

    I have done some small work with a BS1, and now trying to send or
    recieve data through a serial connection to a pc. I have made a
    cable as described in the stamp manual, but to no avil, I cannot send
    or receive data from the stamp. I don't know if it has something to
    do with my port on my computer or something else. The book makes it
    sound simple but maybe I'm still missing something. So if anyone can
    give me some idea's on what to try or tell me what it is that I'm
    missing that would be great as its driving me crazy to what is the
    problem.

    Thanks,
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-01 23:02
    --- In basicstamps@yahoogroups.com, "ard781976" <bluezx3@l...> wrote:
    > Please help,
    >
    > I have done some small work with a BS1, and now trying to send or
    > recieve data through a serial connection to a pc. I have made a
    > cable as described in the stamp manual, but to no avil, I cannot
    send
    > or receive data from the stamp. I don't know if it has something
    to
    > do with my port on my computer or something else. The book makes
    it
    > sound simple but maybe I'm still missing something. So if anyone
    can
    > give me some idea's on what to try or tell me what it is that I'm
    > missing that would be great as its driving me crazy to what is the
    > problem.
    >
    > Thanks,


    Hi,

    Most of my work has been with BS2 and BS2sx, but I think I
    can give you a few things to try.

    First, make sure the PC serial port is working. Jumper pin 2 to
    pin 3 on the computer serial port. Open up a communication software
    program like hyperterm or procomm. When you type on the keyboard, you
    should see characters on the screen. Remove the jumper, and the
    display should behave differently when you type( ie, either no
    characters or only a single character per key). The important thing
    right here is that the screen behaves differently with and without
    the jumper between pin 2 - 3. If connecting-disconnecting the jumper
    gives a different response, then port is OK. If changing the jumper
    doesn't help, also jumper pins 7 - 8 and check again.

    Second, set your stamp in a loop putting out some short string
    like "hello". Connect the stamp 0 volt to pin 5 on the PC. Set the
    stamp baud rate to some low speed like 2400, 8, N, 1. Start up the
    PC communication software ( hyperterm or procomm ) and set it for the
    same speed and other parameters as the stamp. Run a single wire from
    the stamp output pin to pin 3 on the PC. While the stamp runs, you
    should see "hello" on the screen. If you see some unrecognizable
    series of 5 characters, go back to the stamp and select 'true'
    communication parameter, and check again.

    Once you get the transmit part to work, you can then put your
    stamp in a loop to watch for a character from the PC and do something
    like blink an LED to let you know things are happening. Obviously,
    the PC transmits on the other pin (2)and the stamp expects to see the
    data come in a designated pin.

    If it looks like the PC port is not working, go into the start-up
    configuration and make sure the serial port is enabled.

    Despite the aggravation of getting serial to work the first
    time, it is one of the most valuable features of the stamp families.
    Don't give up!

    I hope this is easily related to the BS1!

    Cheers,

    Tom Sisk
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