LPC2103芯片的时钟系统.doc

了解LPC2103芯片的时钟系统。分清晶振频率(FOSC)、处理器时钟(Fcclk)、系统外设时钟(Fpclk)、CCO时钟。通过对锁相环PLL和VPB分频器的配置，实现我们想要的时钟系统。我们开始。先看下面的图。（图一 几种频率的关系。括号里是有关的寄存器名）PLL锁相环：可以通过PLL升频和增强抗干扰性能。VPB分频器: 对PLL时钟分频，供给片上外设使用。区分下面四种时钟频率的概念：晶振频率(FOSC)：外部晶振的频率，我们的板子焊的是11.0592M的。 处理器时钟(Fcclk)：芯片执行指令的频率。Fcclk = FOSC PLL倍频。相关寄存器：PLLCFG4:0。VPB时钟(Fpclk)：给片内外设提供的时钟频率。Fpclk=Fcclk/PLL分频。相关寄存器：APBDIVCCO时钟：不用管它是干什么的。只要把它设置成156MHz320MHz就行。相关寄存器：PLLCFG6:5PLL配置需要的寄存器如下：PLLCON：PLL控制寄存器。控制PLL使能和PLL连接的状态。PLLCFG：PLL配置寄存器。设置PLL倍频和PLL分频。PLLSTAT：PLL状态寄存器。只读寄存器，读出PLL状态。PLLFEED：PLL馈送寄存器。将值0xAA、0x55写入PLLFEED，才能使PLLCON和 PLLCFG的配置生效。VPB配置需要的寄存器APBDIV：VPB分频器。计算频率值：Fosc = 11.0592MHz /外部晶振频率Fcclk = 11.0592*6 = 66.3552MHz /处理器时钟(Fcclk)必须低于芯片的最高频率70MHzFpclk = Fcclk/4 = 16.5888MHz /VPB时钟(Fpclk)Fcco = 66.3552*2*P = 265.4208MHz/必须在156MHz320MHz之间设置过程。先对PLLCFG设置，PLLCON置成使能，但不连接的状态。等待PLL频率锁定以后，最后把PLL设置成连接入状态，把经过PLL倍增的频率接入，作为系统时钟使用。下面是程序例子，在main函数中调用。void Init_VPB_PLL()/Fosc = 11.0592MHz/Fcclk = 11.0592*6 = 66.3552MHz/Fcco = 66.3552*2*P =265.4208MHz/Fpclk =16.5888MHz/ 配置VPB分频器相关寄存器 APBDIV = 0x00; / Fcclk * 1/4 /配置PLL锁相环相关寄存器 PLLCFG = 0x25; / 0 01 00101 分频器值(P=2) 倍增器值(M=6) /PLLCFG=(6-1)|(15); PLLCON = 0x01; / PLLE=1 PLL使能 但PLL未连接 PLLFEED = 0xAA;/ 0xAA 和0x55,为固定数据，写入以后。配置才会生效。 PLLFEED = 0x55; while(PLLSTAT&(110)=0); /等待解锁；PLLSTAT第十位0为未锁1为锁住 PLLCON = 0x03; /PLLE=1 PLLC=1 PLL使能并连接 PLLFEED = 0xAA; PLLFEED = 0x55; /配置/* 系统设置, Fosc、Fcclk、Fcco、Fpclk必须定义*/#define Fosc 11059200 /晶振频率,10MHz25MHz，应当与实际一至#define Fcclk (Fosc * 6) /系统频率，必须为Fosc的整数倍(132)，且=60MHZ#define Fcco (Fcclk * 4) /CCO频率，必须为Fcclk的2、4、8、16倍，范围为156MHz320MHz#define Fpclk (Fcclk / 4) * 1 /VPB时钟频率，只能为(Fcclk / 4)的1, 2 ,4倍PLLCON = 1;/PLL工作 但是没有连接/*设定VPBDIV的时钟*/#if (Fcclk / 4) / Fpclk) = 1 VPBDIV = 0;/APB 总线时钟为处理器时钟的1/4#endif#if (Fcclk / 4) / Fpclk) = 2 VPBDIV = 2;/APB 总线时钟为处理器时钟的1/2#endif#if (Fcclk / 4) / Fpclk) = 4 VPBDIV = 1;/APB 总线时钟与处理器时钟相同#endif/*设定分频和倍频系数*/ #if (Fcco / Fcclk) = 2 PLLCFG = (Fcclk / Fosc) - 1) | (0 5);/分频为1倍频为1#endif#if (Fcco / Fcclk) = 4 PLLCFG = (Fcclk / Fosc) - 1) | (1 5);/分频为2倍频为2#endif#if (Fcco / Fcclk) = 8 PLLCFG = (Fcclk / Fosc) - 1) | (2 5);/分频为4倍频为3#endif#if (Fcco / Fcclk) = 16 PLLCFG = (Fcclk / Fosc) - 1) | (3 5);/分频为8倍频为3#endif PLLFEED = 0xaa; PLLFEED = 0x55; while(PLLSTAT & (1 10) = 0);/等待解锁；PLLSTAT第十位0为未锁1为锁住 PLLCON = 3; PLLFEED = 0xaa; PLLFEED = 0x55; 我用IAR软件哪位大侠说一下FIQ使用的流程！#include iolpc2103.h#include #include #define VPBDIV (*(volatile unsigned char *) 0xE01FC100)#define IOPIN (*(volatile unsigned long *) 0xE0028000)#define Fosc 11059200 /外部晶振频率 11.0592M#define Fcclk (Fosc * 4) /处理器时钟 Fosc * 4#define Fpclk (Fcclk / 4) * 1 /VPB时钏频率#define Fcco (Fcclk * 4) /PLL的操作频#define LED1 1 17#define LED2 1 18#define LED3 1 19#define LED4 1 20_fiq _arm void fiq_handler(void)IOCLR = LED1|LED2|LED3|LED4;void PLL_Init()/* 设置系统各部分时钟 */PLLCON = 1; /使能PLL但不连接 PLLCON.E = 1,PLLCON.C = 0if (Fpclk / (Fcclk / 4) = 1) VPBDIV = 0; / VPBDIV = 0,则Fpclk = 1/4 Fcclk (复位值)if (Fpclk / (Fcclk / 4) = 2) VPBDIV = 2; /VPBDIV = 2,则Fpclk = 1/2 Fcclkif (Fpclk / (Fcclk / 4) = 4) VPBDIV = 1; /VPBDIV = 1,则Fpclk = Fcclk;if (Fcco / Fcclk) = 2) PLLCFG = (Fcclk / Fosc) - 1) | (0 5);if (Fcco / Fcclk) = 4) PLLCFG = (Fcclk / Fosc) - 1) | (1 5);if (Fcco / Fcclk) = 8) PLLCFG = (Fcclk / Fosc) - 1) | (2 5);if (Fcco / Fcclk) = 16) PLLCFG = (Fcclk / Fosc) - 1) | (3 5);PLLFEED = 0xaa;PLLFEED = 0x55;while(PLLSTAT & (1 10) = 0);PLLCON = 0x00000011;PLLFEED = 0xaa;PLLFEED = 0x55;void GPIO_Init()PINSEL0 = 0x00000000;PINSEL1 = 0x00000000; /设置P0.16为EINT0IODIR = LED1|LED2|LED3|LED4;IOSET = LED1|LED2|LED3|LED4;void VIC_Init()VICIntEnClear = 0xffffffff; /中断全部使能关闭VICSoftIntClear = 0xffffffff; /清除软件中断VICProtection= 0; /清除VIC保护VICVectAddr = 0; /清除向量IRQ中断服务程序地址VICDefVectAddr = 0; /清除非向量IRQ中断服务程序地址/清除所有向量IRQ地址VICVectAddr0 = VICVectAddr1 = VICVectAddr2 = VICVectAddr3 = VICVectAddr4 = VICVectAddr5 = VICVectAddr6 = VICVectAddr7 = VICVectAddr8 = VICVectAddr9 = VICVectAddr10 = VICVectAddr11 = VICVectAddr12 = VICVectAddr13 = VICVectAddr14 = VICVectAddr15 = 0;VICVectCntl0 = VICVectCntl1 = VICVectCntl2 = VICVectCntl3 = VICVectCntl4 = VICVectCntl5 = VICVectCntl6 = VICVectCntl7 = VICVectCntl8 = VICVectCntl9 = VICVectCntl10 = VICVectCntl11 = VICVectCntl12 = VICVectCntl13 = VICVectCntl14 = VICVectCntl15 = 0;void EINT0_Init() PINSEL1 = PINSEL1 | 0x01;/设定P0.16连接到EINT0 VICIntSelect = 114; /选择EINT0 为FIQ中断 VICIntEnab