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TMS320F28377D: Question on Baud rate calculation for SCI

Lee Young
Prodigy 250 points
Part Number: TMS320F28377D

Hello,

       I am trying to use the SCI function in TMS320F28377D. From the document SPRUHM8F  page 2006, Table19-3, for baud rate of 9600, the BRR value should be 650 based on the formula, However, 650 in hex should be '0x28A', I don't understand what does that 1616h mean. And I tried to use 0x16 for SCIHBAUD and 0x16 for SCILBAUD, it does't work. If I use 0x28A for the registers, the communication works, but sometimes with a lot of wrong data. I am guessing the baud rate is not quite matching between the two devices . Could anyone explain what does 1616h mean and how can I make my baud rate precise? Thank you!

  • 0
    Guru 192875 points

    Hi,

    The formula is:

    For example if LSPCLK = 15MHz (Please check for your device)

    BRR = [15e6/(9600*8)]-1

             = 194dec

                           =  C2hex

    Lower 8-bits are written to SCILBAUD and higher 8-bits to SCIHBAUD. Hence C2 is directly written to SCILBAUD while leaving SCIHBAUD at null value or 0.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Prodigy 250 points

    Hi Gautam,

        Thank you for your reply. The formula is what I used to calculate my BRR. But the problem is : I am using 50Mhz LSPCLK, and need 9600 baud rate, so I need BRR= 650(dec) = 28A(hex), I just don't understand what the 1616h mean in the manual.

  • 0 in reply to Lee Young
    Guru 192875 points

    Just noticed, they don't seem like equivalent Hex values! Here's a table from F2802x family SCI userguide:

    This makes sense!

  • 0 in reply to Gautam Iyer
    TI__Guru 60865 points
    Hi Li,

    The decimal values in the table are correct, but the hex values are wrong. You are correct that for 9600 baud the hex value should be 0x028A.

    I'll submit a ticket to have this corrected in the documentation.