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Dynamic adjustment frequency*

This paper mainly introduces how to adjust the frequency of the hardware module. The input clock of the chip's CPU, NPU, Flash and Sram modules all come from PLL.

1. PLL configuration:*

notice

Note that the pll clock configuration can only be powered on once. See the detailed source code: boards/nationalchip/grus_gx8002b_dev_1v/clock_board.c

1.1 PLL 24M configuration*

  • Refer to the following code to complete the PLL 24M configuration:
    boards/nationalchip/grus_gx8002b_dev_1v/clock_board.c
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    static GX_CLOCK_PLL pll = {
    .pll_enable      = 1,

    .pll_in          = 32768,
    .pll_fvco        = 98304000,
    .pll_out         = 24576000,

    .pll_div_in      = 0,
    .pll_div_fb      = 3071,
    .pll_icpsel      = 2,
    .pll_bwsel_lpf   = 0,
    .pll_vco_subband = 3,
    .pll_div_out     = 1,

    .pll_itrim       = 0,
    .pll_vco_trim    = 4,
    .pll_2nd3nd_lpf  = 0,
    .pll_lock_tiehi  = 0,
};
gx_clock_set_pll(&pll);

1.2 PLL 50M configuration*

  • Refer to the following code to complete the PLL 50M configuration:
    boards/nationalchip/grus_gx8002b_dev_1v/clock_board.c
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    static GX_CLOCK_PLL pll = {
    .pll_enable      = 1,

    .pll_in          = 32768,
    .pll_fvco        = 98304000,
    .pll_out         = 49152000,

    .pll_div_in      = 0,
    .pll_div_fb      = 3071,
    .pll_icpsel      = 2,
    .pll_bwsel_lpf   = 0,
    .pll_vco_subband = 3,
    .pll_div_out     = 0,

    .pll_itrim       = 0,
    .pll_vco_trim    = 4,
    .pll_2nd3nd_lpf  = 0,
    .pll_lock_tiehi  = 0,
};
gx_clock_set_pll(&pll);

2. Dynamic adjustment frequency*

  • All frequency adjustments are adjusted by the following function.

    include/driver/gx_clock/gx_clock_v2.h
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    /**
 * @brief DIV allocation configuration
 *
 * @param module Note For details, see GX_CLOCK_MODULE
 * @param div    Integer frequency division
 *
 * @return None
 */
void gx_clock_set_div(GX_CLOCK_MODULE module, int div)

    notice

    The value of div is the PLL frequency divided by the target frequency and rounded.

2.1 Dynamically adjust the CPU frequency*

  • If the PLL is 50M, set the CPU frequency to 8M 
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    gx_clock_set_div(CLOCK_MODULE_SCPU, 6)

  • If the PLL is 24 MB, set the CPU frequency to 8 MB 

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    gx_clock_set_div(CLOCK_MODULE_SCPU, 3)

    Get CPU frequency

    int cpu_fre = gx_clock_get_module_frequence(CLOCK_MODULE_SCPU);

2.2 Dynamically adjust the NPU frequency*

  • If the PLL is 50M, set the NPU frequency to 8M 
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    gx_clock_set_div(CLOCK_MODULE_NPU, 6)

  • If the PLL is 24M, set the NPU frequency to 8M 

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    gx_clock_set_div(CLOCK_MODULE_NPU, 3)

    Obtain the NPU frequency

    int npu_fre = gx_clock_get_module_frequence(CLOCK_MODULE_NPU);

2.3 Dynamically adjust the Flash frequency*

  • In the case of PLL 50M, set the Flash frequency to 50M 
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    gx_clock_set_div(CLOCK_MODULE_FLASH_SPI, 1)

  • When the PLL is 24M, the Flash frequency is set to 24M 

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    gx_clock_set_div(CLOCK_MODULE_FLASH_SPI, 1)

    Get Flash frequency

    int flash_fre = gx_clock_get_module_frequence(CLOCK_MODULE_FLASH_SPI);

2.4 Dynamically adjust Sram frequency*

  • In the case of PLL 50M, Sram frequency is adjusted to 25M 
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    gx_clock_set_div(CLOCK_MODULE_SRAM, 2)

  • In the case of PLL 24M, the Sram frequency is adjusted to 12M 

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    gx_clock_set_div(CLOCK_MODULE_SRAM, 2)

    Gets the Sram frequency

    int sram_fre = gx_clock_get_module_frequence(CLOCK_MODULE_SRAM);

notice

  • It is recommended that we first call unsigned int state = gx_lock_irq_save() to get the current interrupt state and close the interrupt. Then call gx_clock_set_div(GX_CLOCK_MODULE module, int div) for frequency modulation. The frequency modulation process is instantaneous, and the end of the interface operation means that frequency modulation is complete. Finally, gx_unlock_irq_restore(state) is called to restore the currently saved interrupt.

  • For details, see Interface LvpDynamiciallyAdjustCpuFrequency in lvp/common/lvp_system_init.c

  • unsigned int gx_clock_get_module_frequence(GX_CLOCK_MODULE module) This interface is used to obtain the module clock frequency