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Re: UART is transmitting grabage on the hyper-terminal screen

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  • Mihai Galos
    Fourier, The clock for the UART is actualy the bit rate. See the chapter Examples of Baud Rate Setting in you microcontoller s datasheet. For example, for
    Message 1 of 5 , Aug 29, 2008
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      Fourier,
      The clock for the UART is actualy the bit rate. See the chapter
      "Examples of Baud Rate Setting" in you microcontoller's datasheet.
      For example, for atmega48 running at 1Mhz(default) for a 4800bps data
      rate, set UBRR to 12. (U2xn bit is 0).

      When you say you hit a key and another character writes on the
      terminal, you give no info about the hardware you are using:

      1)What type of microcontroller?
      2)What is the wireing of the UART pins ?
      3)Are you using the max232 EIA to TTL voltage level converter?
      4)If so, are you using the correctly sized capacitors for this?

      We cannot help you unless you take some time and write in a lot more
      words the problems you are experiences and the hardware you are using.

      For further reading, see
      http://mihaigalos.ro/work/Embedded/Simple/UART/readOn.html
      (entire URL might contain spaces, delete any spaces and copy paste in
      browser).

      Kind regards,
      Mihai GALOS.


      --- In booksbybibin@yahoogroups.com,
      "fourier902000" <fourier902000@...> wrote:
      >
      > --- In booksbybibin@yahoogroups.com, "Mihai Galos" <mihaigalos@>
      wrote:
      > >
      > > Dear fourier,
      > > Please explain yourself using more words because your english
      > > prevents us from understanding you.
      > >
      > > Such an UART behaviour as i think you are trying to describe at
      1)
      > > can be caused by :
      > >
      > > - capacitor values inconsistent with the datashhet for the
      max232
      > > (or equivalanet) TTL to EIA sinal converter (you are using one,
      RIGHT
      > > ?!)
      > > - high noise environment
      > > - uncalibrated bit rates (refer to setting bit rates in the AVR
      > > datasheet)
      > >
      > > Kind regards,
      > > Mihai GALOS
      > >
      > > --- In booksbybibin@yahoogroups.com,
      > > "fourier902000" <fourier902000@> wrote:
      > > >
      > > > Hello
      > > > I'am in the process of writing a Uart code that is intended to
      read
      > > > sensor values and out those values a PC screen.
      > > >
      > > > However the first part of the process is completed, code run
      and
      > > > compile but one thing ...
      > > >
      > > > 1) if a letter is typed from the keyboard I don't see the
      correct
      > > > output. Meaning if A is pressed on the keyboard B is output on
      the
      > > > screen.
      > > >
      > > > 2) The second part of my project is to take values from the A/
      D
      > > > registers and displayed those values on the Hyperteminal.( any
      idea
      > > > how to go about this ?)
      > > >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      > I am sorry about my english!!
      >
      >
      > when I type a character from the keyboard what I see is some
      other
      > character which is different from the keystroke that was depressed
      .
      >
      > How do you set the internal clock ?
      > >
      >
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