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AM2434: UART Baud rate

Christian Dahlke
Prodigy 40 points
Part Number: AM2434
Other Parts Discussed in Thread: SYSCONFIG

Hi,

Is it possible to use a different baud rate than the ones described in the manual for one of the uarts?
For example by specifying another source clock? I tried it to set with sysconfig, but it didn't work.

I'm looking for a baud rate of 3.125 Mbps.

Another thing I noticed in the reference manual is that the clock source ist specified with 48 MHz, but in SysConfig the default value is 96MHz. The communication works with 96 Mhz but not with 48 MHz. 

Thanks + Regards,

Christian Dahlke

  • 0
    TI__Mastermind 49325 points

    Hi Christian,

    You should be able to change the baudrate to 3Mbps and 5Mbps. The 3.125Mbps may not work, because the 96/3.125 is 30.72 which is not integer divisible of 96Mhz. Which MCU+ SDK version are you using? There are some changes in MCU+ SDK 08.04.00.17. The UART input clock frequency was changed from 48Mhz to 96Mhz. Please try the latest MCU+ SDK 08.05.00.17.

    Best regards,

    Ming

  • 0 in reply to Ming Wei
    Prodigy 40 points

    Hi Ming,

    I'm using the MCU+ SDK 08.04.0, not sure what the last digits are. I get it running at 3Mbps, but i wanted to achieve 3.125Mbps.

    Ming Wei said:
    The 3.125Mbps may not work, because the 96/3.125 is 30.72 which is not integer divisible of 96Mhz.


    This sounds like 3.125Mbps won't work with a new SDK either? Trying with another SDK version is a bit complicated, because my project is based on the BNI framework.

    Best Regards, 

    Christian

  • 0 in reply to Christian Dahlke
    TI__Mastermind 49325 points

    Hi Christian,

    I doubt the 3.125Mbps will work based on the above reason, even with the newer release, because the input clock is 96Mhz since 08.04.00.17.

    Bestregards,

    Ming

  • 0 in reply to Ming Wei
    Prodigy 40 points

    And the clock base can't be changed?

  • 0 in reply to Christian Dahlke
    TI__Mastermind 49325 points

    Hi Christian,

    As you can see from the following diagram, the functional clock for UART is either MAIN_PLL1_HSDIV0_CLKOUT(192Mhz)/[1-4] or MAIN_PLL1_HSDIV1_CLKOUT (160Mhz)

       

    192/3.125 = 61.44

    96/3.125 = 30.72

    64/3.125 = 20.48

    32/3.125 = 10.24

    160/3.125 = 51.2

    Your best bet is to use the MAIN_PLL1_HSDIV1_CLKOUT (160Mhz). It will get you to 3.137Mhz (160/51) which is the closest you can get for 3.125Mhz.

    Bestregards,

    Ming

  • 0 in reply to Ming Wei
    Prodigy 40 points

    Thanks Ming,

     I will try this, this should be close enough.

    Best regards,

    Christian