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AM2434: MCU_HFOSC0_CLKOUT

Annie Liu
Genius 10295 points
Part Number: AM2434
Other Parts Discussed in Thread: SYSCONFIG

Hi Team,

Customer needs to use the GTC clock when designing the system. He wants to know what is the frequency of the MCU_HFOSC0_CLKOUT signal, how to calculate it, and where to set it? For example: GTC input clock needs 500MHz, system crystal oscillator, 25MHz, select MAIN_PLL2_HSDIV5_CLKOUT, how to set it?

Referring to the EMMC1 module, he uses the int32_t SOC_moduleSetClockFrequency(uint32_t moduleId, uint32_t clkId, uint64_t clkRate) function. There are only two reference input clocks, why TISCI_DEV_MMCSD1_..._CLK has 0~7, a total of 8 options?

Best regards,

Annie

  • 0
    TI__Expert 7630 points

    Hi Annie,

    The MCU_HSOSC0_CLKOUT signal is the output from the high frequency crystal oscillator, this will be a fixed frequency that depends on the value of the crystal oscillator (typically 25MHz).

    For instance, if your goal is for the GTC to have a 500MHz clock input, then you would have to modify the input source to the peripheral. The TRM does not currently have information on clock frequencies, so we urge customers to use the clock tree tool for AM64x. This can be found in dev.ti.com under SysConfig:

    SysConfig (ti.com)

    In here, selecting the GTC peripheral will generate and show the clock tree relating to that ip:

    You can see that selecting MAIN_PLL2_HSDIV5_CLKOUT as a clock source will yield 225MHz, if you want to 500MHz then selecting MAIN_SYSCLK0 will achieve that:

    Opening the register dump files will tell you which registers will need to be modified in order to obtain this new configuration:

    in TRM:

    As for your software API question, these definitions do not really correspond only to the possible clock sources for the IP but rather they are the full signal instance list of clocks running in and out of the IP as represented by this diagram:

    I am not sure what the usage of the definitions of these files is, it might just be definitions that can be used to configure sysconfig metadata as seen in the file "mmcsd_am243x.sysconfig.js", where one of these values is assigned to the module clock:

    This seems to also indicate that the only two sources for the module's xin_clk are either MAIN_PLL2_HSDIV2_CLKOUT or MAIN_PLL0_HSDIV5_CLKOUT

    Hope this helps clear things up

    Best,

    Daniel