ARM_PLLCON &syetem initializtion 学习

最新推荐文章于 2020-12-23 09:48:42 发布

原创最新推荐文章于 2020-12-23 09:48:42 发布 · 813 阅读

1 ·

CC 4.0 BY-SA版权

文章标签：

#date #signal #system

本文详细介绍了ARM CPU的初始化过程，包括PLL配置步骤，并给出了具体的代码实现。此外，还介绍了A/D转换的设计步骤及注意事项，通过实例展示了如何进行A/D转换。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

The first study of arm ----a diary of arm cpu study!

----sdenven

Fosc :晶振频率

Fcco：PLL电流控制振荡器的频率

Fcclk：PLL输出频率(CPU频率)

Fpclk：外设时钟频率；

PLLCON基本操作方法：

① PLLCON=0x01 ,即PLLE位置位，使能PLL部件；

② design VPBDIV(VPB-clock)PLLCFG寄存器，即倍频值（M）和分频值（P）；

③ PLLFEED=0xaa，PLLFEED=0x55，// 发送馈送序列

④ 读取PLLSTAT的值，等待PLL锁定；

⑤ PLLCON=0x03，即PLLC位置位，连接PLL时钟；

⑥ PLLFEED=0xaa，PLLFEED=0x55，// 发送馈送序列。

void System_Init(void)
{
#define PLL_VPBDIV 0x00 // VPB=1/4 CCLK;
#define PLL_CFG  0x25 // 6倍 10MHz
PLLCON=1;   // enable PLL
VPBDIV=PLL_VPBDIV; // VPB=(1/4)CCLK
PLLCFG=PLL_CFG;  // bit(4:0)M={Fcclk/Fosc-1}=5;bit(6.5)P=2;
PLLFEED=0xAA;  // 发送馈送序列
PLLFEED=0x55;
while(PLLSTAT&(1<<10)==0);// 等待PLL锁定指定频率
PLLCON=0x03; // 使能和连接
PLLFEED=0xAA; // 发送馈送序列
PLLFEED=0x55;
}

that is all ,and you can design the first step initializtion system of arm cup!

this is a ad convert of arm cup! the ad design is very easy but there have some attentions!

The design step of A/D convert:

① design ADCR(32bits)--bit7...bit0 for channel bit21for form and bit24 for ad start;

② design ADDR(32bits)--bit15...bit6 is data of ad bit31 is a flag of over!

pay attention at very time at the end of the ad convert,there must have a new start signal for the next!

for example:

#define Fpclk 10000000

void ARMAD_Init(void)
{
  AD0CR =(1<<0)    |    // SEL=1,selection channel one
    ((Fpclk/1000000-1)<<8)|    // CLKDIV=1MHz
    (0<<16)|
    (0<<17)|
    (1<<21)|
    (0<<22)|
    (1<<24)|
    (0<<27);
//AD0CR =0x01208001;
}

long ARMAD_Convert(void)
{
long ad_date=0;
while((AD0DR&0x80000000)==0);

//pay attention please:there must be a new ad start signal!
AD0CR |=(1<<24);
//AD0CR =0x01208001;
while((AD0DR&0x80000000)==0);
//AD0CR =0x01208001;

//pay attention please:there must be a new ad start signal!

AD0CR |=(1<<24);
ad_date=AD0DR;
ad_date=(ad_date>>6)&0x3ff;
ad_date=ad_date*3300;
ad_date/=1024;
return ad_date;
}