Constant esp_idf_sys::soc_module_clk_t_SOC_MOD_CLK_REF_TICK

pub const soc_module_clk_t_SOC_MOD_CLK_REF_TICK: soc_module_clk_t = 11;

< REF_TICK is derived from APB, it has a fixed frequency of 1MHz even when APB frequency changes