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Having a system clock different than the EVM

Jeremiah Ferguson
Intellectual 385 points

I have a custom board using the C6748. I am using DSP/BIOS 5.41.09.34 and PSP drivers 1.03.01.

Originally we were operating the C6748 at 300 MHz, the same clock rate as the LogicPD SOM. Everything worked just fine once I linked in the NULL pmi and pscl libraries. Now, I am attempting to change the system clock to be at 372MHz, but any of the peripherals running off of PLL0 are not working. I have updated the GEL file and the TCF file with the new PLL settings and resulting clock rate. What else do I need to do in order to get the PSP drivers to use the new System clock? I know it is still using the default 300MHz due to the fact when I look at the UART0 registers, the divisor registers are still the old values calculated from a system clock of 300MHz.

  • 0
    TI__Expert 5500 points

    Hi Jeremiah,

    Apart from updating the GEL file and the TCF file with the new PLL settings, you should also modify the peripheral frequencies in "soc_C6748.h" file(Line: 1111) placed in - pspdrivers_01_30_01\packages\ti\pspiom\cslr\ of the pspdrivers package. The drivers uses these macros to configure the clocks settings. UART for instance, uses these enumerations to calculate the divisor values and to set the baudrate.

    Best Regards,

    Raghavendra 

  • 0 in reply to Raghavendra Maddikery
    Intellectual 385 points

    Modifying these macros is not enough. They are used in compiled code, which means I have to re-compile every PSP driver that I am using. And what makes this solution even less appealing, is that we have two different custom boards that we are building, one is at the default 300MHz (only about 50% cpu utilization) and one at 372MHz. This solution would require us to have two different versions of the PSP drivers loaded and linked into our projects.

  • 0 in reply to Jeremiah Ferguson
    TI__Expert 5500 points

    Hi Jeremiah,

    Sorry for the delayed response..

    Yes ofcourse, you will have to rebuild all the PSP driver you are using. The driver including the modified header file has to be rebuilt. 

    Jeremiah Ferguson said:
    This solution would require us to have two different versions of the PSP drivers loaded and linked into our projects.

    Instead, you can have two different header files(Eg: soc1_C6748.h, soc2_C6748.h) with required modifications and include them accordingly in the respective drivers and rebuild.

    Best Regards,

    Raghavendra