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TMS320F28027: SCI programming - auto baud detection

Darko Hadzidedic
Prodigy 170 points
Part Number: TMS320F28027
Other Parts Discussed in Thread: C2000WARE

We are using opto isolated (open collector) SCI interface. It works well at 4800 baud in normal operation. Now we are trying to use it for serial programming and could not get it faster than 1200 baud. With extensive resistor changes I got it to work at 2400. Our target is 9600 bauds. It seems auto baud detection is failing even though signal rise and fall times look pretty good (see photo for 2400baud). Do you have boot loader option w fixed speed or other suggestion to solve the issue?

Regards,
Darko 

  • 0
    TI__Genius 17315 points
    Darko,

    It looks like you are experiencing slew rate issues with your opto isolated SCI interface, which is limiting reliable auto-baud detection. As you know, the SCI bootloader operates with auto baud detection. To operate with a fixed baud rate speed you can try achieving a baud-lock between the host and the F28027 SCI bootloader using your known good lower baud rate (1200 or 2400). Then load the application (or custom loader) at this lower baud rate to the F28027. The host can then handshake with the loaded application to set the SCI baud rate register to the desired fixed baud rate. For more information please see the TMS320x2802x Piccolo Boot ROM Reference Guide:

    www.ti.com/lit/SPRUFN6

    I hope this helps. If this answers your question, please click the green "Verified Answer" button. Thanks.

    - Ken
  • 0 in reply to Ken Schachter
    Prodigy 170 points

    Hi Ken,

    Thanks for your help.

    We are planning to use proposed solution using custom loader.

    Our SW team already has source code for 'serial_flash_programmer.exe' utility and we should be covered on host side.

    Currently we are using 'f28027_flash_kernel.txt'. I suppose that is the custom loader image running from RAM. Would you be able to provide source code so we could modified it for our project?

    Regards,
    Darko

  • 0 in reply to Darko Hadzidedic
    TI__Mastermind 32995 points
    Darko,

    The example and source code is provided in C2000Ware.

    Both the kernel and the serial flash programmer are available.

    Also, please see: www.ti.com/.../sprabv4b.pdf

    sal