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OMAP-L137 UART problems

Erik Svensson
Prodigy 60 points
Other Parts Discussed in Thread: OMAP-L137

Hello,

I have been trying to use UART2 on the OMAP-L137 EVM board. I have connected the serial cabel to a computer and used the setting 115200, 8 bit, no parity, 1 stop. I have loaded the uart_test program into the DSP. The uart_test program has been modified not to check echo. But I don't seem to receive the correct data, I never receive the correct data and loose most. Has anyone successfully used the code provided by spectrum digital or should I look for problems on the computer side?

  • 0
    TI__Mastermind 24340 points

    Hi Erik,

    Not sure about the spectrum digital test.

    But the PSP example works fine for me. After you follow the GSG, it will be at:

    C:\Program Files\Texas Instruments\pspdrivers_01_20_00_07\packages\ti\pspiom\examples\evm6747\uart\edma\build\uartSample.pjt

     

  • 0
    TI__Mastermind 24340 points

     

    Another thing that comes to mind is that the spectrum example is not converting to ASCII format - and it has to be in ASCII format to show correctly.

     

  • 0
    Prodigy 20 points

    Hi,

    in the Spectrum Digital test in file evmomapl137_uart.c in function EVMOMAPL137_UART_open( Uint16 id, Uint32 baudrate )
     the divisor is incorrectly calculated:

            /*
             *  UART clk / baudrate
             *  = 24,000,000 / (115200 * 16)
             */
            divisor = 24000000 / ( baudrate * 16);

    It is using the quartz clock while it should should use Sys Clock 2 (after PLL multiplication). You need to modify the function to use Sys Clock 2 set by GEL file (I believe 300 000 000 - 300 MHz) or by you during initialization. Also, you may need to get rid of the SD lib and add source files to the project.

    Regards

    Maciek

  • 0 in reply to Maciek Piechota
    TI__Mastermind 24340 points

    Maciek, good catch!

    So the divisor needs to be:

    divisor = 150000000/(baudrate *16);

    to work as is.

    So you need to edit the file:

    ...\evmc6747_v1\dsp\lib\bsl\evmc6747_uart.c

    You can re-compile BSL or just add it to your project for the changes to take effect.

    I will provide feedback about this internally and to spectrum.

     

  • 0 in reply to Mariana
    Prodigy 60 points

    As I suspected. I was going to look at this but made it lower priority. Now that you have a full solution I had to test it and the solution works for me!

    Thanks Maciek and Mariana!

    Regards,
    Erik Svensson