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T3-mini serial ports information

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  • yo5pmp
    Hi, I am trying to wire a ulbox max-7c gps module, but the tracker doesn t decode the NMEA data from the GPS. I tested the GPS module with a TTL to USB
    Message 1 of 9 , Feb 11 11:39 AM
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      Hi,

      I am trying to wire a ulbox max-7c gps module, but the tracker doesn't decode the NMEA data from the GPS. I tested the GPS module with a TTL to USB converter and it works.
      I also tried to simulate the gps by sending NMEA data from my computer via a TLL converter and the tracker functionality still doesn't work.
      The rest of functionalities from the T3-mini are working as expected, the only problem is with the serial ports.

      Is there a special configuration on the tracker to use the serial port for gps data?
      Mention that I set in otwincfg.exe both ports on Auto, 9600 baud and the autobaud checkbox to checked.

      Thanks
    • Jason KG4WSV
      ... Doesn t the T3-mini expect RS232, not TTL? -Jason kg4wsv
      Message 2 of 9 , Feb 11 3:06 PM
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        On Tue, Feb 11, 2014 at 1:39 PM, <yo5pmp@...> wrote:
        I tested the GPS module with a TTL

        Doesn't the T3-mini expect RS232, not TTL?

        -Jason
        kg4wsv
      • yo5pmp
        The GPS module has TTL at 3.3V logical communication, but according with the T3-mini schematic this isn t a problem, because the board has a build-in logical
        Message 3 of 9 , Feb 11 3:30 PM
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          The GPS module has TTL at 3.3V logical communication, but according with the T3-mini schematic this isn't a problem, because the board has a build-in logical conversion to 5V.

          From what i know RS232 has the same protocol with TTL but the logical communication is at 12V, but again according with the T3-mini board schematic this isn't a problem.


          regards

          yo5pmp

        • Jason KG4WSV
          ... You re partially correct, but not close enough. True rs232 (rs232c, Iiirc) uses 12v and -12v where TTL uses 0v and 5v. Not only are the voltages
          Message 4 of 9 , Feb 11 4:25 PM
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            > On Feb 11, 2014, at 5:30 PM, <yo5pmp@...> wrote:
            >
            > From what i know RS232 has the same protocol with TTL but the logical communication is at 12V, but again according with the T3-mini board schematic this isn't a problem.

            You're partially correct, but not close enough.

            True rs232 (rs232c, Iiirc) uses 12v and -12v where TTL uses 0v and 5v. Not only are the voltages different, but the levels are inverted.

            Looks like the t3 mini is configurable for TTL or rs232 - try flipping that setting and see if it helps.

            -Jason
          • Nigel Johnson, MIEEE
            ... Hash: SHA1 RS232 operates with + and - 12V. Actually the driver can be +/- 30V. The logic is inverted though. You can drive RS232 receivers if you invert
            Message 5 of 9 , Feb 11 5:11 PM
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              RS232 operates with + and - 12V. Actually the driver can be +/- 30V. The logic is inverted though. You can drive RS232 receivers if you invert the TTL logic, and you can receive RS232 into TTL if you clamp the signal so it does not go outside 0 to 5.25V, and also invert its sense.

              73 de Nigel ve3id


              On 02/11/2014 06:30 PM, yo5pmp@... wrote:
              > The GPS module has TTL at 3.3V logical communication, but according with the T3-mini schematic this isn't a problem, because the board has a build-in logical conversion to 5V.
              > From what i know RS232 has the same protocol with TTL but the logical communication is at 12V, but again according with the T3-mini board schematic this isn't a problem.
              >
              >
              > regards
              >
              > yo5pmp
              >



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            • yo5pmp
              thanks for your answers, According with the T3-mini product page Its serial ports can be configured for RS-232 or TTL operation . Do you know how to modify
              Message 6 of 9 , Feb 12 12:38 AM
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                thanks for your answers,


                According with the T3-mini product page "Its serial ports can be configured for RS-232 or TTL operation".

                Do you know how to modify this setting? I don't find any option for this configuration in the settings program otwincfg.exe.


                73 de yo5pmp

              • excitontx
                Yo, Indeed, you do need to get the voltage levels and polarities correct for the TTL and RS232 settings. There is also a polarity issue with respect to the
                Message 7 of 9 , Feb 12 8:16 AM
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                  Yo,
                  Indeed, you do need to get the voltage levels and polarities correct for the TTL and RS232 settings.  There is also a polarity issue with respect to the received data.  If you search this Group, you will see some comments using the "PATCH" command to set the received GPS polarity. (PATCH 005FFF0102 will invert RX polarity, and PATCH 005FFF0100 will set it back).  I have used several GPS brands/models with the T3, some need inversion and some not.  And lastly, you need to be sure that the GPS is sending out sentences that the T3 will read (T3 works with $GPRMC, $GPGGA, and $GPGLL sentences).  Good luck,
                  Chuck / KG5CA
                • yo5pmp
                  I solved the problem without using any logical voltage level converter. I used the PATCH 005FFF0102 command and after that the NMEA data was parsed correctly
                  Message 8 of 9 , Feb 12 4:16 PM
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                    I solved the problem without using any logical voltage level converter. I used the "PATCH 005FFF0102" command and after that the NMEA data was parsed correctly by the T3-mini.
                    thanks all for help, 73 de yo5pmp
                  • Scott Miller
                    PATCH 005FFF0102 sets the RX invert bit. PATCH 005FFF0100 clears it. You ll need to reset the tracker after running the command. Scott
                    Message 9 of 9 , Feb 12 7:19 PM
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                      PATCH 005FFF0102 sets the RX invert bit.
                      PATCH 005FFF0100 clears it.

                      You'll need to reset the tracker after running the command.

                      Scott

                      On 2/12/2014 12:38 AM, yo5pmp@... wrote:
                       

                      thanks for your answers,


                      According with the T3-mini product page "Its serial ports can be configured for RS-232 or TTL operation".

                      Do you know how to modify this setting? I don't find any option for this configuration in the settings program otwincfg.exe.


                      73 de yo5pmp


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