/*---------------------------------------------------------------------------------------------------------*/
/* PLLCON constant definitions. PLL = FIN * NF / NR / NO */
/*---------------------------------------------------------------------------------------------------------*/
#define CLK_PLLCON_PLL_SRC_HXT 0x00000000UL /*!< For PLL clock source is HXT. 4MHz < FIN < 24MHz */
#define CLK_PLLCON_PLL_SRC_HIRC 0x00080000UL /*!< For PLL clock source is HIRC. 4MHz < FIN < 24MHz */
#define CLK_PLLCON_NR(x) (((x)-2)<<9) /*!< x must be constant and 2 <= x <= 33. 1.6MHz < FIN/NR < 15MHz */
#define CLK_PLLCON_NF(x) ((x)-2) /*!< x must be constant and 2 <= x <= 513. 100MHz < FIN*NF/NR < 200MHz. (120MHz < FIN*NF/NR < 200MHz is preferred.) */
#define CLK_PLLCON_NO_1 0x0000UL /*!< For output divider is 1 */
#define CLK_PLLCON_NO_2 0x4000UL /*!< For output divider is 2 */
#define CLK_PLLCON_NO_4 0xC000UL /*!< For output divider is 4 */
#define CLK_PLLCON_50MHz_HXT (CLK_PLLCON_PLL_SRC_HXT | CLK_PLLCON_NR(3) | CLK_PLLCON_NF( 25) | CLK_PLLCON_NO_2) /*!< Predefined PLLCON setting for 50MHz PLL output with 12MHz X'tal */
#define CLK_PLLCON_50MHz_HIRC (CLK_PLLCON_PLL_SRC_HIRC | CLK_PLLCON_NR(13) | CLK_PLLCON_NF( 59) | CLK_PLLCON_NO_2) /*!< Predefined PLLCON setting for 50.1918MHz PLL output with 22.1184MHz IRC */
/*---------------------------------------------------------------------------------------------------------*/
/* MODULE constant definitions.
上面的
#define CLK_PLLCON_NR(x) (((x)-2)<<9)
#define CLK_PLLCON_NF(x) ((x)-2)
其中的“X”的值是多少？为什么要减 2 又左移9位？
#define CLK_PLLCON_NO_2 0x4000UL /*!< For output divider is 2 */ OUT
NO_2=OUT_DV = 0x01 这里又是什么意思？
请大师详解！ |
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楼主
