下面这张图,就是6410的系统时钟原理图:的 6410的时钟频率决定公式:FOUT
= MDIV * FIN / (PDIV * 2^SDIV) 其中这几个值(MDIV,PDIV,SDIV)都在APLL_CON和MPLL_CON中。 FIN就是我们系统输入时钟,ok6410是12Mhz。 要得到最后的输出时钟都要设置 DIV分频器 ARMCLK = DOUTAPLL / (ARM_RADIO + 1) CLK_DIV0 mainly controls the system clocks and special
clocks of multimedia IP s. The output frequencies of
APLL and MPLL are divided by ARM_RATIO and MPLL_RATIO. HCLKX2 clock is the base clock of other
operating system clocks and divided by HCLKX2_RATIO. There is operating frequency limitation. The maximum
operating frequency of HCLKX2, HCLK, and PCLK are 266MHz, 133MHz, and 66MHz, respectively. NAND,
SECUR, JPEG operating clock cannot exceed 66MHz. MFC and CAM operating clock cannot exceed 133MHz.
This operating clock condition must be met through CLK_DIV0 configuration. 这是手册上的一段话,也就是HCLK*2的频率不能超过266Mhz。jpeg,cam频率都有限制。APLL给ARM
CPU使用 MPLL给主设备、HCLK(内存,DDR),PCLK(外设片上模块) EPLL给其它模块