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Change CPU frequency of OMAPL138

Long Di
Prodigy 30 points
Other Parts Discussed in Thread: OMAPL138

Dear all,

          I want to check if we want to update the CPU frequency of the OMAPL 138, besides the following two steps:     

          1. Change  Core_300MHz_mDDR_150MHz() to Core_456MHz_mDDR_150MHz() in OMAPL138_LCDK.gel,   

          2. Update  #define SOC_SYSCLK_1_FREQ         (300000000) to (456000000) in soc_OMAPL138.h，

          Do we need to change any other components?

          Thanks a lot!

Dee

  • 0
    TI__Guru** 116170 points
    Dee,

    I would recommend that you look at the clocking spreadsheet provided here:
    processors.wiki.ti.com/.../AM18xx

    When you modify the CPU clock, a number of SYSCLK that are dependent on the SYSCLK1 will increase accordingly you will also need to look at the module dividers for other SYSCLKs to ensure that they are running inside the spec specified by datasheet. The clock spreadsheet should tell you if you are violating the spec for any of the system clocks.

    Since you mentioned soc_OMAPL138.h, I am assuming you are using starterware. If you see the macro SOC_SYSCLK_1_FREQ is only used to commute values of other SYSTEM clocks and is not used to program the PLL values. The place were you change this would be where the PLL0Init and PLL1Init APIs are being called. Those are the APIs that really program the device PLL and system clocks using PLL registers.

    Eg: BlPlatformConfig() function in the bootloader.

    the other place where this is critical is when setting up UART baud rate of 115.2 Kbps. you may need to change the PRESCALAR and oversampling in the UART module to get to 115.2 Kbps when SYSCLK1 is 456Mhz. look at the UART tab in the clocking spreadsheet.

    Regards,
    Rahul